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Editor Work2014 Vol. 22, No. s1
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2014, 22(s1): 1-6.
Abstract
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Recently, the center of coal mining is transferring from the east to the midwest in China. But in these regions, with the arid and semi-arid climate and fragile ecological environment, the mining is going to have a significant impact on the quite limited water resources. From the development of the preceding years, this problem has led to a seriously restriction on the coal production. Taking Shennan mining area in Northern Shaanxi for an example, the paper discusses the scientific problem of water preserved mining.In the analysis, the paper introduces water system to the above scientific problem and this system integrates the whole water resources in the range of the mining area. For the water system,before mining, the input is rainfall and output is the discharge of the surface run-off. All of the factors in this system keep in balance with a certain detained capacity within the mining area containing surface water, and water in sandy layer and burned rock. In comparison, after mining, the inputs will contain invariable rainfall and bedrock fissure water and at the same time, the output will decrease because of the leakage of the surface water under the influence of the mining. The above analysis obtains a conclusion-mining is going to increase the capacity of the retained water resources in the mining area and this increasing capacity is good for water preserved mining.
Recently, the center of coal mining is transferring from the east to the midwest in China. But in these regions, with the arid and semi-arid climate and fragile ecological environment, the mining is going to have a significant impact on the quite limited water resources. From the development of the preceding years, this problem has led to a seriously restriction on the coal production. Taking Shennan mining area in Northern Shaanxi for an example, the paper discusses the scientific problem of water preserved mining.In the analysis, the paper introduces water system to the above scientific problem and this system integrates the whole water resources in the range of the mining area. For the water system,before mining, the input is rainfall and output is the discharge of the surface run-off. All of the factors in this system keep in balance with a certain detained capacity within the mining area containing surface water, and water in sandy layer and burned rock. In comparison, after mining, the inputs will contain invariable rainfall and bedrock fissure water and at the same time, the output will decrease because of the leakage of the surface water under the influence of the mining. The above analysis obtains a conclusion-mining is going to increase the capacity of the retained water resources in the mining area and this increasing capacity is good for water preserved mining.
2014, 22(s1): 7-10.
The point load test was used for the tensile strength measurement of coal samples. Integrity coefficient of the coal was calculated based on the wave velocity tests of coal seam in situ and coal samples. Finally, the tensile strength of coal seam was calculated by the transformation relationship between point load strength and tensile strength according to the quasi coal strength theory. The results show the integrity coefficient of coal is 0.47 and the tensile strength is 0.08MPa. The research results can provide scientific basis for underground engineering application of coal tensile strength index.
The point load test was used for the tensile strength measurement of coal samples. Integrity coefficient of the coal was calculated based on the wave velocity tests of coal seam in situ and coal samples. Finally, the tensile strength of coal seam was calculated by the transformation relationship between point load strength and tensile strength according to the quasi coal strength theory. The results show the integrity coefficient of coal is 0.47 and the tensile strength is 0.08MPa. The research results can provide scientific basis for underground engineering application of coal tensile strength index.
2014, 22(s1): 11-18.
Mine geo-environment risk decision making is a consultation process to meet multiple objects from multi-stakeholder. In order to control mine risk in the mine life cycles, the decision making was employed to approach three objects which were meeting acceptable risk, getting the most benefit from control engineering and making reasonable plan for mine closure. Then, the hierarchical analysis was applied to multiple criteria decision making in risk management of mine geo-environment. Lastly, the consultation process was used to determine the engineering proposal that control the geo-environment risk of a limestone mine in Fengshan, Guangxi. The process considered some information from multi-stakeholder including design organization, government and local people. It indicates that the optimal engineering proposal has four parts, i.e. P1 with cutting slope, clearing up unstable rock and anchoring; P2 with drainage, rockfall platform and monitoring; P3 with smoothing slope surface, carving and vegetation; P4 with risk education. It is not only a guidance to rebuilt environment of the limestone mine, but also has positive affect to develop mine closure.
Mine geo-environment risk decision making is a consultation process to meet multiple objects from multi-stakeholder. In order to control mine risk in the mine life cycles, the decision making was employed to approach three objects which were meeting acceptable risk, getting the most benefit from control engineering and making reasonable plan for mine closure. Then, the hierarchical analysis was applied to multiple criteria decision making in risk management of mine geo-environment. Lastly, the consultation process was used to determine the engineering proposal that control the geo-environment risk of a limestone mine in Fengshan, Guangxi. The process considered some information from multi-stakeholder including design organization, government and local people. It indicates that the optimal engineering proposal has four parts, i.e. P1 with cutting slope, clearing up unstable rock and anchoring; P2 with drainage, rockfall platform and monitoring; P3 with smoothing slope surface, carving and vegetation; P4 with risk education. It is not only a guidance to rebuilt environment of the limestone mine, but also has positive affect to develop mine closure.
2014, 22(s1): 19-26.
Shanxi Province is the birthplace of Chinese civilization. Glorious history left use xtremely rich and valuable cultural heritage, including geological disasters. Research summary the history of geological disasters in Shanxi has a very important significance for us to further understand the modern geological disasters. A large number of historical literature describes a number of geological disasters in Shanxi. The authors conducted careful research to summarize the development of its basic law and the spatial and temporal characteristics of the geological disastersfrom written records, the historical evolutionofthe title, the overall number, geographical distribution, genetic type etc. five aspects, and made a useful exploration of the historical period geological disasters research, broadening the research field of geological disasters and filling the gaps in this regard. And the authors put forward basic methods for historical research of geological disasters according to own practice.
Shanxi Province is the birthplace of Chinese civilization. Glorious history left use xtremely rich and valuable cultural heritage, including geological disasters. Research summary the history of geological disasters in Shanxi has a very important significance for us to further understand the modern geological disasters. A large number of historical literature describes a number of geological disasters in Shanxi. The authors conducted careful research to summarize the development of its basic law and the spatial and temporal characteristics of the geological disastersfrom written records, the historical evolutionofthe title, the overall number, geographical distribution, genetic type etc. five aspects, and made a useful exploration of the historical period geological disasters research, broadening the research field of geological disasters and filling the gaps in this regard. And the authors put forward basic methods for historical research of geological disasters according to own practice.
2014, 22(s1): 27-31.
In recent years, the ground subsidence disaster of Zibo area is becoming increasingly serious, and is a hazard to engineering construction and personnel safety of life and property. The article focus on the main control factors and mechanisms which cause ground subsidence in Zibo area; it is based on the theory of structural geology, hydrogeology, engineering mechanics and so on. It is concluded that because of the high strength pumping groundwater in mining or living, the water tables are plummeting, so the soil of the surface loses the supporting force of groundwater, causing the ground above to cave in. The research result has the theoretical and practical significance to prevent and control ground subsidence of Zibo area.
In recent years, the ground subsidence disaster of Zibo area is becoming increasingly serious, and is a hazard to engineering construction and personnel safety of life and property. The article focus on the main control factors and mechanisms which cause ground subsidence in Zibo area; it is based on the theory of structural geology, hydrogeology, engineering mechanics and so on. It is concluded that because of the high strength pumping groundwater in mining or living, the water tables are plummeting, so the soil of the surface loses the supporting force of groundwater, causing the ground above to cave in. The research result has the theoretical and practical significance to prevent and control ground subsidence of Zibo area.
2014, 22(s1): 32-36.
There is lots of mined-out area in Beijing Fangshan region due to mining building stone, which is a kind of adverse geologic actions in highway construction. Stability evaluation and treatment on subgrade of highway in mined-out area is quite difficult because of no planning, disorderly, and repeatedly excavation, the distribution and complicated boundary conditions of mined-out area. This article used the criterion mining conditions method, limit equilibrium analysis method, collapse self-obliteration method and the protodyakonov's theory to discuss the stability evaluation and treatment measures for a mined-out area of Jingshi second highway(Da yuan village～Beijing municipal boundary).
There is lots of mined-out area in Beijing Fangshan region due to mining building stone, which is a kind of adverse geologic actions in highway construction. Stability evaluation and treatment on subgrade of highway in mined-out area is quite difficult because of no planning, disorderly, and repeatedly excavation, the distribution and complicated boundary conditions of mined-out area. This article used the criterion mining conditions method, limit equilibrium analysis method, collapse self-obliteration method and the protodyakonov's theory to discuss the stability evaluation and treatment measures for a mined-out area of Jingshi second highway(Da yuan village～Beijing municipal boundary).
2014, 22(s1): 37-42.
Paste stockpiling is a new method which was used for tailings disposal in tailing pond. It is also applied in the tailing pond of BaoGang West Mine. The stability of tailings dam is the key factor that making sure the safety of paste stockpiling. By using Geo-Studio software and based on the tailing pond of BaoGang West Mine the impact of different depth of water on the south dam stability were analyzed. The stability of north dam, in different height of tailings, were studied. In order to prevent possible failure of south dam, the depth of water is suggested no more than 8m, otherwise measures should be taken to reinforce the south dam. The north dam is always safety no matter on the condition of 8m accumulation height or 23m accumulation height.
Paste stockpiling is a new method which was used for tailings disposal in tailing pond. It is also applied in the tailing pond of BaoGang West Mine. The stability of tailings dam is the key factor that making sure the safety of paste stockpiling. By using Geo-Studio software and based on the tailing pond of BaoGang West Mine the impact of different depth of water on the south dam stability were analyzed. The stability of north dam, in different height of tailings, were studied. In order to prevent possible failure of south dam, the depth of water is suggested no more than 8m, otherwise measures should be taken to reinforce the south dam. The north dam is always safety no matter on the condition of 8m accumulation height or 23m accumulation height.
2014, 22(s1): 43-47.
The Shanghaimiao mine is located in the southwest part of the Inner Mongolian Autonomous Region, and in the northwestern edge of the Erdos basin, which is one of the most important energy coal mine bases in China. The coal mine in this area is characterized by the large burial depth and complicated exploitation conditions. The laboratory tests were carried out to investigate the permeability, swelling, collapse and softening coefficients by utilizing the core samples attained during the geotechnical investigation drilling. The test results show that the permeability and softening properties of coarse sandstone, fine sandstone, siltstone, silty mudstone tend to decrease. The collapse coefficient of coarse sandstone is clearly lower, and that of fine sandstone is slighter higher than others',but those of three sets of silty mudstone are rather scattered. The free swelling coefficients of medium coarse sandstone, fine sandstone and siltstone tend to decline respectively, but those of three sets of silty mudstone are rather scattered too. The mineral ingredients of rock samples include quartz, potash feldspar, plagioclase and clay minerals, but the content of clay minerals are not stable. By comparing the test results, the hydraulic properties seem to not be irrelevant to the mineral contents, which still needs further research. These research findings are of great significance to the latter coal exploitation.
The Shanghaimiao mine is located in the southwest part of the Inner Mongolian Autonomous Region, and in the northwestern edge of the Erdos basin, which is one of the most important energy coal mine bases in China. The coal mine in this area is characterized by the large burial depth and complicated exploitation conditions. The laboratory tests were carried out to investigate the permeability, swelling, collapse and softening coefficients by utilizing the core samples attained during the geotechnical investigation drilling. The test results show that the permeability and softening properties of coarse sandstone, fine sandstone, siltstone, silty mudstone tend to decrease. The collapse coefficient of coarse sandstone is clearly lower, and that of fine sandstone is slighter higher than others',but those of three sets of silty mudstone are rather scattered. The free swelling coefficients of medium coarse sandstone, fine sandstone and siltstone tend to decline respectively, but those of three sets of silty mudstone are rather scattered too. The mineral ingredients of rock samples include quartz, potash feldspar, plagioclase and clay minerals, but the content of clay minerals are not stable. By comparing the test results, the hydraulic properties seem to not be irrelevant to the mineral contents, which still needs further research. These research findings are of great significance to the latter coal exploitation.
2014, 22(s1): 48-52.
Metal mine ground cracks caused by underground mining become a serious of mine geological environment problems and appeal more and more attention. Jingerquan appeares quantities of ground fissures and lager area of ground collapse because it adopted short-hole shrinkage method in the early time. Afterwards, back filling method was adopted in order to protect from collapsing the building around the mining area. Based on the actual reconnaissance survey and long-term ground GPS monitoring data, the changing rules and formation mechanism of ground fissures are discussed from the forming and developing trend of surface crack. This article provids theory basis for the safety of mining production.
Metal mine ground cracks caused by underground mining become a serious of mine geological environment problems and appeal more and more attention. Jingerquan appeares quantities of ground fissures and lager area of ground collapse because it adopted short-hole shrinkage method in the early time. Afterwards, back filling method was adopted in order to protect from collapsing the building around the mining area. Based on the actual reconnaissance survey and long-term ground GPS monitoring data, the changing rules and formation mechanism of ground fissures are discussed from the forming and developing trend of surface crack. This article provids theory basis for the safety of mining production.
2014, 22(s1): 53-57.
Longde is located in southern Ningxia, which is a serious water shortage area. The economic development is mainly depend on the exploitation of shallow groundwater. Therefore, through sampling and analysis of the test from the three valleys, according to the chemical characteristics of the groundwater and factor analysis, this paper discusses the formation of the district diving mechanisms. The result shows that：Shallow groundwater of the area buries shallow; quiet water depth is 10.3～25.6m; evaporation and concentration effect control the groundwater chemical types. Ion exchange occurs mainly in the valley downstream. The main aquifer mineral is cloud stone, gypsum, salt, which is affected by ground water runoff and aquifer buried condition; the degree of dissolution and precipitation is different; groundwater salinity is low; the chemistry type of groundwater is mainly carbonated and carbonic acid.
Longde is located in southern Ningxia, which is a serious water shortage area. The economic development is mainly depend on the exploitation of shallow groundwater. Therefore, through sampling and analysis of the test from the three valleys, according to the chemical characteristics of the groundwater and factor analysis, this paper discusses the formation of the district diving mechanisms. The result shows that：Shallow groundwater of the area buries shallow; quiet water depth is 10.3～25.6m; evaporation and concentration effect control the groundwater chemical types. Ion exchange occurs mainly in the valley downstream. The main aquifer mineral is cloud stone, gypsum, salt, which is affected by ground water runoff and aquifer buried condition; the degree of dissolution and precipitation is different; groundwater salinity is low; the chemistry type of groundwater is mainly carbonated and carbonic acid.
2014, 22(s1): 58-61.
In the investigation of geotechnical engineering, according to criterion, we need evaluate the corrosiveness of water and soil in foundation depth. If the area of site is large, water and soil samples will be a big number due to evaluation including many factors, if all work is done by hand, workload will be heavy. Because the test results is in MS Excel type, the VBA method can be fast and accurate to evaluate corrosiveness of water and soil, and thus provide better services for investigation report.
In the investigation of geotechnical engineering, according to criterion, we need evaluate the corrosiveness of water and soil in foundation depth. If the area of site is large, water and soil samples will be a big number due to evaluation including many factors, if all work is done by hand, workload will be heavy. Because the test results is in MS Excel type, the VBA method can be fast and accurate to evaluate corrosiveness of water and soil, and thus provide better services for investigation report.
2014, 22(s1): 62-69.
Quaternary loose strata which is formed with young age and large thickness provides the physical basis for land subsidence in the Yellow River Delta. The effects of tectonic movement, sediment consolidation and sea level rise on land subsidence have been long. In recent decades, the large-scale human activities of increasing exploitation of groundwater and oil and gas, high-rise building construction, etc, are becoming new triggers. The superimposition of various inducing factors have resulted in complication of spatial-temporal differentiation and formation mechanism. Based on leveling and relevant background data, this paper analyzes the characterization of land subsidence in Guangrao County and Dongying District where human activities are concentrated. After the comprehensive comparison of various human and natural subsidence factors, the annual subsidence contribution rate of groundwater overexploitation, large engineering construction, oil and gas exploitation, neotectonic movement, natural consolidation of sediment and sea level rise are approximately 28:4:2:3:2:1. Human activities have played a leading role on land subsidence.
Quaternary loose strata which is formed with young age and large thickness provides the physical basis for land subsidence in the Yellow River Delta. The effects of tectonic movement, sediment consolidation and sea level rise on land subsidence have been long. In recent decades, the large-scale human activities of increasing exploitation of groundwater and oil and gas, high-rise building construction, etc, are becoming new triggers. The superimposition of various inducing factors have resulted in complication of spatial-temporal differentiation and formation mechanism. Based on leveling and relevant background data, this paper analyzes the characterization of land subsidence in Guangrao County and Dongying District where human activities are concentrated. After the comprehensive comparison of various human and natural subsidence factors, the annual subsidence contribution rate of groundwater overexploitation, large engineering construction, oil and gas exploitation, neotectonic movement, natural consolidation of sediment and sea level rise are approximately 28:4:2:3:2:1. Human activities have played a leading role on land subsidence.
2014, 22(s1): 70-76.
The distribution of groundwater has a great influence on the stability of the reservoir slope. Taking Shuping landslide for example, Visual Modflow software was adopted in numerical simulation calculation on seepage field under different conditions. The conclusions are as follows：the groundwater level changes with the reservoir water level fluctuations; the water level is less affected on the trailing edge of the landslide, while it's changed significantly on the middle and the front edge; in the process of reservoir water level falling, the relationship between the time and water level in the landslide shows the following characteristics：stable water level, falling down fast, slowly falling and stable water level. And the different falling speed only affects the water level change rate, while having not effect on the final water level; with the increase of reservoir water drop speed, the greater the landslide leading edge of the underground water level changes, the greater the hydraulic gradient becomes, and the hydraulic gradient becomes largest on the both side of the border of the landslide. And the paper also provides a reference for landslide groundwater seepage field changes and its stability analysis in Three Gorges Reservoir.
The distribution of groundwater has a great influence on the stability of the reservoir slope. Taking Shuping landslide for example, Visual Modflow software was adopted in numerical simulation calculation on seepage field under different conditions. The conclusions are as follows：the groundwater level changes with the reservoir water level fluctuations; the water level is less affected on the trailing edge of the landslide, while it's changed significantly on the middle and the front edge; in the process of reservoir water level falling, the relationship between the time and water level in the landslide shows the following characteristics：stable water level, falling down fast, slowly falling and stable water level. And the different falling speed only affects the water level change rate, while having not effect on the final water level; with the increase of reservoir water drop speed, the greater the landslide leading edge of the underground water level changes, the greater the hydraulic gradient becomes, and the hydraulic gradient becomes largest on the both side of the border of the landslide. And the paper also provides a reference for landslide groundwater seepage field changes and its stability analysis in Three Gorges Reservoir.
2014, 22(s1): 77-82.
Soil-caves collapse in karst area is a common geological hazard, which make some disaster accidents. However, the critical condition of forming soil-cave is seldom researched now. Based on the theories of pipe flow, this paper derives the formulas of the critical hydraulic condition for assessing soil-caves. The cohesive soils from Wuxuan county, Guangxi province, China, are chosen to be tested to obtain the critical value by a designed test method. Combining the critical value and the monitoring hydraulic data, the results show the current hydraulic condition will not form soil-caves.
Soil-caves collapse in karst area is a common geological hazard, which make some disaster accidents. However, the critical condition of forming soil-cave is seldom researched now. Based on the theories of pipe flow, this paper derives the formulas of the critical hydraulic condition for assessing soil-caves. The cohesive soils from Wuxuan county, Guangxi province, China, are chosen to be tested to obtain the critical value by a designed test method. Combining the critical value and the monitoring hydraulic data, the results show the current hydraulic condition will not form soil-caves.
2014, 22(s1): 83-87.
In recent years, the slope instability caused by rainfall infiltration more and more frequently, and more and more experts attach importance to this subject. As a result, numerical simulation study of slope instability caused by angle of slope under rainfall is of great importance both in theory and application to engineering. In this paper, there are two factors, duration of rainfall and the different angle of slope, which affect the stability of slope are studied based on numerical simulation. According to the characteristics of sand used in the construction site, the angle of rainfall on the course of the effects of slope stability safety factor. The results show that under the same rainfall intensity, the same rainfall time, the smaller angle of slope is,the latter and faster the safety factor declines, the greater change in soil pore water pressure, Finally, the displacement of soil will enhance, the stability of slope will decrease. There are three processes including the unsteady seepage, the unsteady seepage and the steady seepage, steady seepage inside the slope. The numerical simulation results can provide an improved understanding of the physical behavior and failure mode of soil slopes subjected to rainfall.
In recent years, the slope instability caused by rainfall infiltration more and more frequently, and more and more experts attach importance to this subject. As a result, numerical simulation study of slope instability caused by angle of slope under rainfall is of great importance both in theory and application to engineering. In this paper, there are two factors, duration of rainfall and the different angle of slope, which affect the stability of slope are studied based on numerical simulation. According to the characteristics of sand used in the construction site, the angle of rainfall on the course of the effects of slope stability safety factor. The results show that under the same rainfall intensity, the same rainfall time, the smaller angle of slope is,the latter and faster the safety factor declines, the greater change in soil pore water pressure, Finally, the displacement of soil will enhance, the stability of slope will decrease. There are three processes including the unsteady seepage, the unsteady seepage and the steady seepage, steady seepage inside the slope. The numerical simulation results can provide an improved understanding of the physical behavior and failure mode of soil slopes subjected to rainfall.
2014, 22(s1): 88-93.
At present, the study of landslide dam body stability is more at home and abroad. But most of the studies are individual cases. In all the factors which influence the stability of the landslide dam, the landslide dam material composition and its permeability characteristics of dam failure mode is important. On the base of previous investigations, from the basic rule of seepage flow, numerical simulation, laboratory test three aspects are summarized for landslide dam material seepage mechanism and research methods. The focus is on the research progress of landslide dam material permeability. It is points out that the geometric conditions and hydraulic conditions that determine the soil seepage deformation and seepage stability. Then the paper summarizes the problems existing in current studies on the landslide dam material penetration. Finally, possible research direction in the future are pointed out.
At present, the study of landslide dam body stability is more at home and abroad. But most of the studies are individual cases. In all the factors which influence the stability of the landslide dam, the landslide dam material composition and its permeability characteristics of dam failure mode is important. On the base of previous investigations, from the basic rule of seepage flow, numerical simulation, laboratory test three aspects are summarized for landslide dam material seepage mechanism and research methods. The focus is on the research progress of landslide dam material permeability. It is points out that the geometric conditions and hydraulic conditions that determine the soil seepage deformation and seepage stability. Then the paper summarizes the problems existing in current studies on the landslide dam material penetration. Finally, possible research direction in the future are pointed out.
2014, 22(s1): 94-99.
This paper based on the subject of MI Huai Shun groundwater reservoir storage and water quality security research, analysis the ability of artificial recharge in the Chaobai River by measuring the attenuation of recharge volume and the variation of permeability coefficient after well irrigation test was carried out in Chaobai River. The test results show that the unit lifting recharge amount of well irrigation is 58.8～73.1m3(h.m)-1. There is a gradual attenuation phenomenon with the decay rate of well irrigation recharge 1.4m3(h.m)-1 on well irrigation. It is strong recharge ability and feasible technology that using water well recharge. The single well recharge amount can reached 300～350m3h-1. Analytical methods and test results can provide reference for the similar experimental research and engineering applications.
This paper based on the subject of MI Huai Shun groundwater reservoir storage and water quality security research, analysis the ability of artificial recharge in the Chaobai River by measuring the attenuation of recharge volume and the variation of permeability coefficient after well irrigation test was carried out in Chaobai River. The test results show that the unit lifting recharge amount of well irrigation is 58.8～73.1m3(h.m)-1. There is a gradual attenuation phenomenon with the decay rate of well irrigation recharge 1.4m3(h.m)-1 on well irrigation. It is strong recharge ability and feasible technology that using water well recharge. The single well recharge amount can reached 300～350m3h-1. Analytical methods and test results can provide reference for the similar experimental research and engineering applications.
2014, 22(s1): 100-103.
Compared with general civil engineering investigation, highway engineering geological investigation has its own significant feature-longer line, more engineering geological units, more construction sites, more survey methods. To ensure the survey quality, we have to control the whole line geological condition. Meanwhile, we also have to regard conditions such as high and steep slope, special span bridge and so on. However, geological investigation marketization is developing without general standard, which affects the investigation quality and development. Based on highway project and investigation report, this article points out that geological survey and engineering design are not relevant enough as the highway project needs, which affects the investigation and design result most. Because owners and design companies always suppress design fee, which prevents the investigation engineers to accomplish their inspiration, then limits the design level. More importantly, it may lead engineering accidents. In order to cater to the market, companies have to pay more attention on contract amount than investigation quality, which is another negative factor that will prevent the benign development of investigation industry.
Compared with general civil engineering investigation, highway engineering geological investigation has its own significant feature-longer line, more engineering geological units, more construction sites, more survey methods. To ensure the survey quality, we have to control the whole line geological condition. Meanwhile, we also have to regard conditions such as high and steep slope, special span bridge and so on. However, geological investigation marketization is developing without general standard, which affects the investigation quality and development. Based on highway project and investigation report, this article points out that geological survey and engineering design are not relevant enough as the highway project needs, which affects the investigation and design result most. Because owners and design companies always suppress design fee, which prevents the investigation engineers to accomplish their inspiration, then limits the design level. More importantly, it may lead engineering accidents. In order to cater to the market, companies have to pay more attention on contract amount than investigation quality, which is another negative factor that will prevent the benign development of investigation industry.
2014, 22(s1): 104-109.
The super large bridge Kedi Balinghe is one of the key projects of the Guizhou section of the Shanghai-Kunming passenger special line. The geological condition is extremely complicate of the bridge project. Influence factors are topography and geomorphology, formation lithology, geological structure, et al. Rockfall, landslide, rock heap, karst are frequently. Use the surveying and mapping, geophysical prospecting and drilling data to study the type, scale, harmfulness of the engineering geological problems and the countermeasures. The research results have offered the basis for circuit scheme, and have great meanings in design, construction and operation of the bridge.
The super large bridge Kedi Balinghe is one of the key projects of the Guizhou section of the Shanghai-Kunming passenger special line. The geological condition is extremely complicate of the bridge project. Influence factors are topography and geomorphology, formation lithology, geological structure, et al. Rockfall, landslide, rock heap, karst are frequently. Use the surveying and mapping, geophysical prospecting and drilling data to study the type, scale, harmfulness of the engineering geological problems and the countermeasures. The research results have offered the basis for circuit scheme, and have great meanings in design, construction and operation of the bridge.
2014, 22(s1): 110-116.
The region of western China belongs to the north-east edge of Tibet Plateau. Due to the periods of tectonic movements and extrusion of current Tibet Plateau in the direction of NW-NNW,the region characterizes by intense horizontal squeezing, which generally shows a high-stress value. With the development of railway construction, it becomes more and more universal for deep-burial tunnel built in the west of China. As results of this stress condition, the problems induced by excavation of tunnel are exclusive, such as a constantly compressional deformation in lamellar soft rock. And they are chanlleging the tradational methods we uesd to deal with them. Thus, it is necessary for us to figure out current stress status of project area as well as to choose the appropriate axes of tunnel and take full advantage of self-bearing capacity of surrounding rock. In addition, a scientific support design is absolutely necessary. The hydrofracture stress measurement, which can be simply operated and measure deeply, is one of the most effective methods for in-situ stress measurement. We summarize a kind of high geo-stress evaluation derived from Hoek-Brown formula and Byerlee laws. It can appropriately evaluate whether the project zone of tunnel belongs to high geo-stress area by utilizing the result of in-situ stress test and quality of surrounding rock. By means of that, we can assure the construction of tunnel project safe and stabile.
The region of western China belongs to the north-east edge of Tibet Plateau. Due to the periods of tectonic movements and extrusion of current Tibet Plateau in the direction of NW-NNW,the region characterizes by intense horizontal squeezing, which generally shows a high-stress value. With the development of railway construction, it becomes more and more universal for deep-burial tunnel built in the west of China. As results of this stress condition, the problems induced by excavation of tunnel are exclusive, such as a constantly compressional deformation in lamellar soft rock. And they are chanlleging the tradational methods we uesd to deal with them. Thus, it is necessary for us to figure out current stress status of project area as well as to choose the appropriate axes of tunnel and take full advantage of self-bearing capacity of surrounding rock. In addition, a scientific support design is absolutely necessary. The hydrofracture stress measurement, which can be simply operated and measure deeply, is one of the most effective methods for in-situ stress measurement. We summarize a kind of high geo-stress evaluation derived from Hoek-Brown formula and Byerlee laws. It can appropriately evaluate whether the project zone of tunnel belongs to high geo-stress area by utilizing the result of in-situ stress test and quality of surrounding rock. By means of that, we can assure the construction of tunnel project safe and stabile.
2014, 22(s1): 117-121.
Hengfu special railway is located in high terrace in Shanxi Hongtong Fenhe valley., Loess is the main engineering geological problem of this project. There are three layer of loess, Alluvial and diluvial causes and age of late quaternary holocene(Q42), the early Holocene (Q41) and late pleistocene(Q3). Three layers are sandy loess, which belong to the hard soil, with low natural gravity, natural void ratio, less natural water content and low liquid limit and plastic limit, small plasticity index and liquidity index, low saturation, large compression coefficient, high velocity, shear strength and bearing capacity of general characteristics. Physical and mechanical indexes of layer 1 and layer 2 loess are close, which are collapsible loess. The indexes of layer 3 are better, not collapsible loess. The field is self collaspsibility. The collapsibility of loess and natural gravity, natural void ratio, natural water content, liquid limit, saturation and shear wave velocity indexes have close relations. The loess collapsibility has larger influence on bridge and roadbed engineering. It should take different foundation type and treatment measures for different project and loess. The different methods of sampling have great influences on the collapsible loess indexes and characteristics, collapsible loess trial pit manual sampling should be adopted.
Hengfu special railway is located in high terrace in Shanxi Hongtong Fenhe valley., Loess is the main engineering geological problem of this project. There are three layer of loess, Alluvial and diluvial causes and age of late quaternary holocene(Q42), the early Holocene (Q41) and late pleistocene(Q3). Three layers are sandy loess, which belong to the hard soil, with low natural gravity, natural void ratio, less natural water content and low liquid limit and plastic limit, small plasticity index and liquidity index, low saturation, large compression coefficient, high velocity, shear strength and bearing capacity of general characteristics. Physical and mechanical indexes of layer 1 and layer 2 loess are close, which are collapsible loess. The indexes of layer 3 are better, not collapsible loess. The field is self collaspsibility. The collapsibility of loess and natural gravity, natural void ratio, natural water content, liquid limit, saturation and shear wave velocity indexes have close relations. The loess collapsibility has larger influence on bridge and roadbed engineering. It should take different foundation type and treatment measures for different project and loess. The different methods of sampling have great influences on the collapsible loess indexes and characteristics, collapsible loess trial pit manual sampling should be adopted.
2014, 22(s1): 122-129.
Dongla landslide is resurrected in Shuiluo town of Muli city. The causes of the historical experience are ancient landslide, old landslide, resurrecting landslide. Severe deformation of the landslide was since 2011, and tension cracks spread over the landslide, then generate incremental deformation sliding scale destruction. Through deformation characteristics survey and using monitor tools, slip surface is located 18.5～19.5m of the soil. The resurrection of the mechanism of landslides in the mechanical model is the slip-crack destruction. Adverse geological environment, landslide debris and loose rock and soil structure are the base of the landslide geological deformation; impact of human activities are the main factors that may influence the development of potential landslides. The landslide is currently in the stage of creep deformation severe deformation damage, and there is a trend development step by step. Landslide is likely to decline sharply in rainfall, which will destray roads and power plants and the Dongla bridge. The Shuiluo river will be blocked, bring much more damage.
Dongla landslide is resurrected in Shuiluo town of Muli city. The causes of the historical experience are ancient landslide, old landslide, resurrecting landslide. Severe deformation of the landslide was since 2011, and tension cracks spread over the landslide, then generate incremental deformation sliding scale destruction. Through deformation characteristics survey and using monitor tools, slip surface is located 18.5～19.5m of the soil. The resurrection of the mechanism of landslides in the mechanical model is the slip-crack destruction. Adverse geological environment, landslide debris and loose rock and soil structure are the base of the landslide geological deformation; impact of human activities are the main factors that may influence the development of potential landslides. The landslide is currently in the stage of creep deformation severe deformation damage, and there is a trend development step by step. Landslide is likely to decline sharply in rainfall, which will destray roads and power plants and the Dongla bridge. The Shuiluo river will be blocked, bring much more damage.
2014, 22(s1): 130-135.
The excavation of subway will take strongly influence on its surrounding soil, and the safety of surrounding buildings will be threatened while the settlement gets too large. Therefore, the study of the influence of excavation on surrounding environment is of great significance for subway construction. Besides the strata structure, the excavation sequence and excavation footage are two important factors that will change the surrounding environment. In this paper, based on the special soil rock composite geological situation of Changchun area, a numerical simulation for subway construction was performed by using FLAC3D finite differente software, including different excavation sequence and footage during the construction of metro station using PBA method. Through comparison of different schemes, the optimal scheme is determined for this project. These results are also useful for providing a basis for similar projects construction in the future.
The excavation of subway will take strongly influence on its surrounding soil, and the safety of surrounding buildings will be threatened while the settlement gets too large. Therefore, the study of the influence of excavation on surrounding environment is of great significance for subway construction. Besides the strata structure, the excavation sequence and excavation footage are two important factors that will change the surrounding environment. In this paper, based on the special soil rock composite geological situation of Changchun area, a numerical simulation for subway construction was performed by using FLAC3D finite differente software, including different excavation sequence and footage during the construction of metro station using PBA method. Through comparison of different schemes, the optimal scheme is determined for this project. These results are also useful for providing a basis for similar projects construction in the future.
2014, 22(s1): 136-141.
Seismic faults cause a great damage to tunnels in the seismic zone during earthquakes. Therefore, how to reduce seismic damage to tunnels has become a hot issue. Based on a large number of studies of the relationship between magnitude and fault rupture parameters, faults displacement, the empirical correlation between magnitude and fault rupture parameters, surface displacement of Donald L.Wells was further verified using the rupture parameters of 5.12 Wenchuan earthquake. The results showe that empirical validation of values obtained from the relationship between magnitude with surface rupture length, underground rupture, width and the average displacement, are closed to the actual fracture parameters of the Wenchuan earthquake, and indicate that these relationships can be used to estimate rupture parameters of earthquake and provide the best reference to tunnels passing potential faults of earthquake zone in the design and safety evaluation.
Seismic faults cause a great damage to tunnels in the seismic zone during earthquakes. Therefore, how to reduce seismic damage to tunnels has become a hot issue. Based on a large number of studies of the relationship between magnitude and fault rupture parameters, faults displacement, the empirical correlation between magnitude and fault rupture parameters, surface displacement of Donald L.Wells was further verified using the rupture parameters of 5.12 Wenchuan earthquake. The results showe that empirical validation of values obtained from the relationship between magnitude with surface rupture length, underground rupture, width and the average displacement, are closed to the actual fracture parameters of the Wenchuan earthquake, and indicate that these relationships can be used to estimate rupture parameters of earthquake and provide the best reference to tunnels passing potential faults of earthquake zone in the design and safety evaluation.
2014, 22(s1): 142-148.
The quantitative description for coupling effect of vehicle vibration is one of the important issues and difficulties in risk control of overlapped tunnels operation. Based on the analysis for the influencing factors of the overlapped tunnels vibration coupling, the vibration coupling mechanism of the overlapped tunnel system after construction is quantitative analyzed in space and time. The expansibility in space and furtherance in time of the coupling mechanism are also pointed out. According to the intersecting line expansion formula of cylinder and cone, the quantitative description of the coupling regions are obtained. By applying Boussinesq solutions and disturbed state concept theory, the disturbing function of the operating tunnel is theoretically derived.3D analytical solutions for geotechnical state of vibration coupling regions in the overlapped tunnels is gotten. This research has a great significance for the engineering design and quantitative analysis of stability control of overlapped tunnels.
The quantitative description for coupling effect of vehicle vibration is one of the important issues and difficulties in risk control of overlapped tunnels operation. Based on the analysis for the influencing factors of the overlapped tunnels vibration coupling, the vibration coupling mechanism of the overlapped tunnel system after construction is quantitative analyzed in space and time. The expansibility in space and furtherance in time of the coupling mechanism are also pointed out. According to the intersecting line expansion formula of cylinder and cone, the quantitative description of the coupling regions are obtained. By applying Boussinesq solutions and disturbed state concept theory, the disturbing function of the operating tunnel is theoretically derived.3D analytical solutions for geotechnical state of vibration coupling regions in the overlapped tunnels is gotten. This research has a great significance for the engineering design and quantitative analysis of stability control of overlapped tunnels.
2014, 22(s1): 149-155.
The combination of bridge and slope is usually used to pass through high slopes and valleys in the construction of transportation infrastructure projects, such as highway and railway engineering. And on this occasion, as the factors, such as excavation unloading, rainfall and bridge deck loads, can easily give rise to the destruction of the slope, it cannot be too necessary to pay close attention to the health condition of the slope. In this paper, aiming at high slope-bridge combination engineering under the action of excavation, supporting and bridge deck loads, we chose one typical high slope in the Yunfu-Luoding expressway project, and made a series of 3D finite element numerical simulation by Midas. By studying and analyzing the slope stability and stress distribution in the three stages of initial condition, before supporting, and operation stage, we analyzed the mechanical behaviours and stability of the high slope, and the influence to the bridge made by the slope, as well. The simulation results show that, as the original supporting scheme cannot make an effect on ensuring the slope safety, the stability of high slope decreases remarkably after the excavation, and we have also put forward an improved supporting scheme for the project. And, while the influence to the slope made by the bridge deck loads can be obvious within a limit range, it's insignificant to the overall level. And the change of bridge grade caused by the deformation of the high slope won't make a obvious difference to the driving comfort and safety of the bridge. The study in this paper can guide the construction and maintenance of this slope, and provide reference and ideas to the stability evaluation of the bridge-slope combined engineering in future.
The combination of bridge and slope is usually used to pass through high slopes and valleys in the construction of transportation infrastructure projects, such as highway and railway engineering. And on this occasion, as the factors, such as excavation unloading, rainfall and bridge deck loads, can easily give rise to the destruction of the slope, it cannot be too necessary to pay close attention to the health condition of the slope. In this paper, aiming at high slope-bridge combination engineering under the action of excavation, supporting and bridge deck loads, we chose one typical high slope in the Yunfu-Luoding expressway project, and made a series of 3D finite element numerical simulation by Midas. By studying and analyzing the slope stability and stress distribution in the three stages of initial condition, before supporting, and operation stage, we analyzed the mechanical behaviours and stability of the high slope, and the influence to the bridge made by the slope, as well. The simulation results show that, as the original supporting scheme cannot make an effect on ensuring the slope safety, the stability of high slope decreases remarkably after the excavation, and we have also put forward an improved supporting scheme for the project. And, while the influence to the slope made by the bridge deck loads can be obvious within a limit range, it's insignificant to the overall level. And the change of bridge grade caused by the deformation of the high slope won't make a obvious difference to the driving comfort and safety of the bridge. The study in this paper can guide the construction and maintenance of this slope, and provide reference and ideas to the stability evaluation of the bridge-slope combined engineering in future.
2014, 22(s1): 156-163.
Since the 1990s, we have act as a administrative district unit of geological disasters investigation in the 1:500000 to 1:50000,which provides the scientific proof for geological disaster prevention planning and land use planning. Geological disasters in small watershed have a serious threat to urban construction and development in recent years. This paper studies pregnant environment, disaster evolution pattern and rule of geohazads in combining with geohazads investigation in Sunshui river watershed. The main conclusions are as follows：(1)on August 31, 2012, once-in-two-century heavy rainfall hit Sunshui river basin, rainfall of 149.2mm, which induced a large number of geohazads and showed a large number, big size, high density and a line-belt-sheet space distribution characteristics.(2)Spatial distribution is shown as：linear concentrated distribution along the important traffic trunk, such as ChengKun railway, county roads, rural roads; strip concentrated distribution along both sides of the river; the distribution of geological disaster is group.(3)the precipitation effect is obvious by time distribution controlling; the formation of geological hazards and rainfall, rainfall duration, rainfall intensity and the process was a positive correlation. Heavy rain is one of the main factors for the formation of geological disasters, and the ripple effect often forms the disaster chain, and clusters of disasters.(4)Heavy rain disaster chain patterns mainly include：rainstormlandslidebarrier dambarrier dam failurefloods; rainstormdebris flowbarrier dambarrier dam failure floods; rainstorm abandon slaglandslide or debris flow; rainstormbank slope failure buried and high harmony channel.
Since the 1990s, we have act as a administrative district unit of geological disasters investigation in the 1:500000 to 1:50000,which provides the scientific proof for geological disaster prevention planning and land use planning. Geological disasters in small watershed have a serious threat to urban construction and development in recent years. This paper studies pregnant environment, disaster evolution pattern and rule of geohazads in combining with geohazads investigation in Sunshui river watershed. The main conclusions are as follows：(1)on August 31, 2012, once-in-two-century heavy rainfall hit Sunshui river basin, rainfall of 149.2mm, which induced a large number of geohazads and showed a large number, big size, high density and a line-belt-sheet space distribution characteristics.(2)Spatial distribution is shown as：linear concentrated distribution along the important traffic trunk, such as ChengKun railway, county roads, rural roads; strip concentrated distribution along both sides of the river; the distribution of geological disaster is group.(3)the precipitation effect is obvious by time distribution controlling; the formation of geological hazards and rainfall, rainfall duration, rainfall intensity and the process was a positive correlation. Heavy rain is one of the main factors for the formation of geological disasters, and the ripple effect often forms the disaster chain, and clusters of disasters.(4)Heavy rain disaster chain patterns mainly include：rainstormlandslidebarrier dambarrier dam failurefloods; rainstormdebris flowbarrier dambarrier dam failure floods; rainstorm abandon slaglandslide or debris flow; rainstormbank slope failure buried and high harmony channel.
2014, 22(s1): 164-169.
The three-dimensional discrete element model, based on the geological sketch which was carried out to analyse the main joints of the surrounding rocks of the Huashuyan tunnel, was established to investigate the upper and lower bench method and attain the variation of surrounding rock displacement and cable axial force. The results show that：(1)During the construction process, the excavation of the V-grade surrounding rock will only affect the displacement of a certain zone and the length of it is twice the tunnel wide with tunnel face in the middle;(2)The generated settlement, in the excavation of upstairs, accounts for about 94% of the total deposition, and it should be concerned in construction detection;(3)The vertical joints of asymmetry lead to the asymmetry distribution of the cable axial force, and the cable axial force of the right side of the arch is 1.1 times than the left ones; (4)The axial force of those cables at the sidewall and arch foot are small, so the layout of cables in radical direction can be optimized from 180to 90.
The three-dimensional discrete element model, based on the geological sketch which was carried out to analyse the main joints of the surrounding rocks of the Huashuyan tunnel, was established to investigate the upper and lower bench method and attain the variation of surrounding rock displacement and cable axial force. The results show that：(1)During the construction process, the excavation of the V-grade surrounding rock will only affect the displacement of a certain zone and the length of it is twice the tunnel wide with tunnel face in the middle;(2)The generated settlement, in the excavation of upstairs, accounts for about 94% of the total deposition, and it should be concerned in construction detection;(3)The vertical joints of asymmetry lead to the asymmetry distribution of the cable axial force, and the cable axial force of the right side of the arch is 1.1 times than the left ones; (4)The axial force of those cables at the sidewall and arch foot are small, so the layout of cables in radical direction can be optimized from 180to 90.
2014, 22(s1): 170-175.
On both sides of the Dadu River are high steep slope, and have high earthquake intensity, the slope stability come to the control factor on the selection of bridge position of the Luding Dadu river bridge on the highway from Yaan to Kangding. For the three planed bridge site, established the geological model and studied the slope stability and possible damage to the bridge. Research shows that the Shangba and Zhongba bridge site Ya'an shore slope are rock-soil and strong weathered rock slope structure, the soil and weathering rockmass will slide under seismic condition. There have through extraversion structure plane and large area of colluvial soil on the Kangding shore slope of Shangba and Zhongba bridge site, which are instability under the action of earthquake and difficult to control. On the Zali bridge site, the upper part of Ya'an shore slope are ancient river bed sediments, lower bedrock, sedimentary face nearly horizontal, the Kang'ding shore slope are moraine deposits.both side of the Zali bridge site are stable. Comprehensive analysis of three bridge site slope stability and the harm to the bridge, recommended to choose Zali bridge site.
On both sides of the Dadu River are high steep slope, and have high earthquake intensity, the slope stability come to the control factor on the selection of bridge position of the Luding Dadu river bridge on the highway from Yaan to Kangding. For the three planed bridge site, established the geological model and studied the slope stability and possible damage to the bridge. Research shows that the Shangba and Zhongba bridge site Ya'an shore slope are rock-soil and strong weathered rock slope structure, the soil and weathering rockmass will slide under seismic condition. There have through extraversion structure plane and large area of colluvial soil on the Kangding shore slope of Shangba and Zhongba bridge site, which are instability under the action of earthquake and difficult to control. On the Zali bridge site, the upper part of Ya'an shore slope are ancient river bed sediments, lower bedrock, sedimentary face nearly horizontal, the Kang'ding shore slope are moraine deposits.both side of the Zali bridge site are stable. Comprehensive analysis of three bridge site slope stability and the harm to the bridge, recommended to choose Zali bridge site.
2014, 22(s1): 176-181.
Engineering geology, hydrogeology and engineering environmental condition of Baisha river section of Qingdao Metro line M1 is very complex, and may have a serious threat to the tunnel construction security. Based on preliminary survey data, this article conducted a detailed analysis and research on this section, and offers suggestions for problems needs to be focused on during the next detailed investigation. And it also offers certain guiding significance for the engineering investigation, design and construction of similar complex sections of future subway lines.
Engineering geology, hydrogeology and engineering environmental condition of Baisha river section of Qingdao Metro line M1 is very complex, and may have a serious threat to the tunnel construction security. Based on preliminary survey data, this article conducted a detailed analysis and research on this section, and offers suggestions for problems needs to be focused on during the next detailed investigation. And it also offers certain guiding significance for the engineering investigation, design and construction of similar complex sections of future subway lines.
2014, 22(s1): 182-186.
With the widely application of hydraulic tunnel, it is an important problem how to determine the scheme of primary support for hydraulic tunnel. Taking the hydraulic tunnel at Southern Main Canal of the South-North Water Transfer Project as an example, the scheme of primary support for hydraulic tunnel was studied. The results show that the steel fiber sprayed concrete is better than wire mesh concrete of primary support for this hydraulic tunnel, and it can more ensure the construction safety of hydraulic tunnel. The conclusions and suggestions are valuable for the engineering design and worth as references for the similar projects.
With the widely application of hydraulic tunnel, it is an important problem how to determine the scheme of primary support for hydraulic tunnel. Taking the hydraulic tunnel at Southern Main Canal of the South-North Water Transfer Project as an example, the scheme of primary support for hydraulic tunnel was studied. The results show that the steel fiber sprayed concrete is better than wire mesh concrete of primary support for this hydraulic tunnel, and it can more ensure the construction safety of hydraulic tunnel. The conclusions and suggestions are valuable for the engineering design and worth as references for the similar projects.
2014, 22(s1): 187-194.
The problems of karst collapse can't be overlooked to engineering construction. The paper studies the extent of the karst collapse degree of two main factors(impact load and underground water) in high-speed of Guangzhou to Qingyuan. Based on data collection and field research, it concludes 12 points' basic information of karst collapse in research area, and sum up the characters of collapses and main effective factors. Besides, it sets up the geological model of sandy soil silty clay limestone,which conforms with the actual structure of overburden. In addition, it calculates the stability coefficient of overburden under two conditions using the limit equilibrium theory. It turns out the maximum impact loads.
The problems of karst collapse can't be overlooked to engineering construction. The paper studies the extent of the karst collapse degree of two main factors(impact load and underground water) in high-speed of Guangzhou to Qingyuan. Based on data collection and field research, it concludes 12 points' basic information of karst collapse in research area, and sum up the characters of collapses and main effective factors. Besides, it sets up the geological model of sandy soil silty clay limestone,which conforms with the actual structure of overburden. In addition, it calculates the stability coefficient of overburden under two conditions using the limit equilibrium theory. It turns out the maximum impact loads.
2014, 22(s1): 195-201.
The highway and railway linear infrastructure construction will produce many engineering geological problems easily. The past, the future,by summarzing some typical cases of freeway, national and provincial highway and railway construction in Fujian, results show that：landslides(including ancient landslide resurrection),tunnel water inrush, soft soil are the major engineering geological problems of highway and railway engineering in Fujian province. Landslide problems are solved by strengthening the ancient landslide early identification and system survey, the implementation of dynamic design of monitoring feedback, and comprehensive treatment of three-dimensional drainage, load shedding and anti slip anchor retaining; Base on the comprehensive survey in the early stage, the key of prevention of water inrush in tunnel is early advance geological forecast warning monitoring and prevention of phase faults, rock fissures and karst caves in the tunnel construction; Through the survey reveals of the structure characteristics of the soft soil genesis, three-dimensional distribution and physical mechanics, the corresponding treatment are apllied in soft soil foundation of replacement, drainage consolidation, flexible pile, rigid pile, or structure of pile-plate, pile-raft and pile-net.
The highway and railway linear infrastructure construction will produce many engineering geological problems easily. The past, the future,by summarzing some typical cases of freeway, national and provincial highway and railway construction in Fujian, results show that：landslides(including ancient landslide resurrection),tunnel water inrush, soft soil are the major engineering geological problems of highway and railway engineering in Fujian province. Landslide problems are solved by strengthening the ancient landslide early identification and system survey, the implementation of dynamic design of monitoring feedback, and comprehensive treatment of three-dimensional drainage, load shedding and anti slip anchor retaining; Base on the comprehensive survey in the early stage, the key of prevention of water inrush in tunnel is early advance geological forecast warning monitoring and prevention of phase faults, rock fissures and karst caves in the tunnel construction; Through the survey reveals of the structure characteristics of the soft soil genesis, three-dimensional distribution and physical mechanics, the corresponding treatment are apllied in soft soil foundation of replacement, drainage consolidation, flexible pile, rigid pile, or structure of pile-plate, pile-raft and pile-net.
2014, 22(s1): 202-208.
The numerical simulation of the foundation excavation and support on Lushan open-cut metro station of Chengdu metro line 1 was carried out using the software FLAC3D, and the deformation law during the process of foundation construction was obtained. In the course of simulation, a three-dimension model was built and seepage and consolidation was considered to restore the true situation vividly. This simulation offers the settlements of ground surface, uplifts on the bottom of the foundation pit, lateral displacement of soil and horizontal displacement of cast-in-place piles, providing reference for the design and construction of similar engineering.
The numerical simulation of the foundation excavation and support on Lushan open-cut metro station of Chengdu metro line 1 was carried out using the software FLAC3D, and the deformation law during the process of foundation construction was obtained. In the course of simulation, a three-dimension model was built and seepage and consolidation was considered to restore the true situation vividly. This simulation offers the settlements of ground surface, uplifts on the bottom of the foundation pit, lateral displacement of soil and horizontal displacement of cast-in-place piles, providing reference for the design and construction of similar engineering.
2014, 22(s1): 209-215.
It is difficult to get a comprehensive understanding of large soil landslide failure mode by field surveys and other means as conventional drilling. This paper takes Sichuan Liangshan Autonomous Township Kakijiwa landslide for an example. Apply finite difference software FLAC3D combined with the actual landslide geological conditions, geological model, and select weight+storm and hypothetical landslide erosion leading edge for conditional weight+storm two conditions, simulate and study the stability and landslide potential failure modes, expose the maximum stress and displacement during the landslide destroying.
It is difficult to get a comprehensive understanding of large soil landslide failure mode by field surveys and other means as conventional drilling. This paper takes Sichuan Liangshan Autonomous Township Kakijiwa landslide for an example. Apply finite difference software FLAC3D combined with the actual landslide geological conditions, geological model, and select weight+storm and hypothetical landslide erosion leading edge for conditional weight+storm two conditions, simulate and study the stability and landslide potential failure modes, expose the maximum stress and displacement during the landslide destroying.
2014, 22(s1): 216-220.
Osman developed a model to describe the riverbank bank collapse based on the slope stability analysis. This model could reflect the physical process of slope collapse well and had been applied to the breach formation model. During the dam break process, the reservoir water level decrease with the increase of outflow, thus transient seepage flow emerge along the slope plane and the seepage force resulting will decrease stability factor of the slope. In this paper, the seepage force was considered to access the stability of bank based on the Osman model. The failure angle and critical value to access the slope stability were calculated. In addition, the breakage process of Teton dam was simulated based on the basic data provided. In addition, the comparison was made between the simulation results when considering the effect of seepage conditions and neglecting it. The results show that the decrease rate of reservoir water level when considering the seepage effect is faster than that neglecting the effect. It takes longer for reservoir to drain off when neglecting the seepage effect. The seepage force accelerated collapse and shorter the dam breakage duration. In addition, the maximum dam break flow rate is greater when considering the seepage effect.
Osman developed a model to describe the riverbank bank collapse based on the slope stability analysis. This model could reflect the physical process of slope collapse well and had been applied to the breach formation model. During the dam break process, the reservoir water level decrease with the increase of outflow, thus transient seepage flow emerge along the slope plane and the seepage force resulting will decrease stability factor of the slope. In this paper, the seepage force was considered to access the stability of bank based on the Osman model. The failure angle and critical value to access the slope stability were calculated. In addition, the breakage process of Teton dam was simulated based on the basic data provided. In addition, the comparison was made between the simulation results when considering the effect of seepage conditions and neglecting it. The results show that the decrease rate of reservoir water level when considering the seepage effect is faster than that neglecting the effect. It takes longer for reservoir to drain off when neglecting the seepage effect. The seepage force accelerated collapse and shorter the dam breakage duration. In addition, the maximum dam break flow rate is greater when considering the seepage effect.
2014, 22(s1): 221-225.
This paper takes detailed exploration engineering of Diaozhongba landslide in Zhong county of Congqing Tree Gorges Reservoir for an example. Analyzes the the effect of change of the old channel on the stability of the landslide. It has certain guiding significance for accurate analysis causes of landslide near river and proposal for landslide prevention. According to the actual engineering, puts forward treatment measures.
This paper takes detailed exploration engineering of Diaozhongba landslide in Zhong county of Congqing Tree Gorges Reservoir for an example. Analyzes the the effect of change of the old channel on the stability of the landslide. It has certain guiding significance for accurate analysis causes of landslide near river and proposal for landslide prevention. According to the actual engineering, puts forward treatment measures.
2014, 22(s1): 226-231.
There are noticeable differences in the overburden on river bed and the shape of river valley between the upper dam and the lower dam of a hydropower station on the Dadu river. This paper analyses the forming mechanism of the overburden on river bed and the evolution of river valley on the base of geological structure and global climate. TheUshape glacial valley of the upper dam by glaciations in the last ice age in Epipleistocene remains to this day. A intensive erosion in a later period result in deep cutVshape valley at the lower dam and a profile stair between the upper dam and the lower dam. Since Holocene, strong sedimentation and weak erosion result in deep overburden on the deep cut valley of the lower dam, and a barrier lake layer in the middle of overburden.
There are noticeable differences in the overburden on river bed and the shape of river valley between the upper dam and the lower dam of a hydropower station on the Dadu river. This paper analyses the forming mechanism of the overburden on river bed and the evolution of river valley on the base of geological structure and global climate. TheUshape glacial valley of the upper dam by glaciations in the last ice age in Epipleistocene remains to this day. A intensive erosion in a later period result in deep cutVshape valley at the lower dam and a profile stair between the upper dam and the lower dam. Since Holocene, strong sedimentation and weak erosion result in deep overburden on the deep cut valley of the lower dam, and a barrier lake layer in the middle of overburden.
2014, 22(s1): 232-237.
The rapid fluctuation of water level of reservoir is liable to cause accumulation landslide, and the failure of reservoir slope often causes damage to hydraulic structures and reduces storage capacity. So that, study its mechanism and the deformation failure mode is important. The test was performed in a rectangular box with the length of 100cm, the width of 60cm and the height of 60cm. A plastic board was set up in the test box, which was used to simulate the bedrock impervious to water. A sluice was developed to implement the simulation of the rapid drawdown of water level. About 20cm thick accumulation was filled on the plastic board. The sensors were buried in the accumulation and used for measuring earth pressure and pore water pressure during rapid fluctuation of water level. The deformation of slope was recorded during the test process by digital camera. The experimental results indicate that the tensile cracks initiate on the surface of accumulation, and a local failure of slope toe have happened in the raising of water level, as the water decreases shear strength of soil; in the process of water level drawdown, the accumulation slips along rock base, and the residual pore-water pressure is a major factor in landslide. The failure mode of reservoir slope is pull-type, due to the landslide is triggered by seepage force.
The rapid fluctuation of water level of reservoir is liable to cause accumulation landslide, and the failure of reservoir slope often causes damage to hydraulic structures and reduces storage capacity. So that, study its mechanism and the deformation failure mode is important. The test was performed in a rectangular box with the length of 100cm, the width of 60cm and the height of 60cm. A plastic board was set up in the test box, which was used to simulate the bedrock impervious to water. A sluice was developed to implement the simulation of the rapid drawdown of water level. About 20cm thick accumulation was filled on the plastic board. The sensors were buried in the accumulation and used for measuring earth pressure and pore water pressure during rapid fluctuation of water level. The deformation of slope was recorded during the test process by digital camera. The experimental results indicate that the tensile cracks initiate on the surface of accumulation, and a local failure of slope toe have happened in the raising of water level, as the water decreases shear strength of soil; in the process of water level drawdown, the accumulation slips along rock base, and the residual pore-water pressure is a major factor in landslide. The failure mode of reservoir slope is pull-type, due to the landslide is triggered by seepage force.
2014, 22(s1): 238-243.
The geothermal anomaly characteristics at Wudongde hydropower station dam site refer to the Reshuitang fault and the geological environment of underground engineering, so the special geological investigation and analysis were carried out. The results show that：geothermal anomaly is associated with the Reshuitang fault, but it was not the evidence for the Reshuitang fault activities; the hot spring distributed along the fault is classified as medium-low temperature type. The formation of those hot springs attributed to the special topography and geological structure, and the cause of those hot springs stratum-fault compound control mode. The Reshuitang fault is not a active fault, would not affect the adjacent dam site. Springs developed along faults are related with geothermal anomaly in adjacent areas will bring adverse impact on underground engineering construction. So, it should take appropriate engineering measures to ensure safety in the construction process.
The geothermal anomaly characteristics at Wudongde hydropower station dam site refer to the Reshuitang fault and the geological environment of underground engineering, so the special geological investigation and analysis were carried out. The results show that：geothermal anomaly is associated with the Reshuitang fault, but it was not the evidence for the Reshuitang fault activities; the hot spring distributed along the fault is classified as medium-low temperature type. The formation of those hot springs attributed to the special topography and geological structure, and the cause of those hot springs stratum-fault compound control mode. The Reshuitang fault is not a active fault, would not affect the adjacent dam site. Springs developed along faults are related with geothermal anomaly in adjacent areas will bring adverse impact on underground engineering construction. So, it should take appropriate engineering measures to ensure safety in the construction process.
2014, 22(s1): 244-248.
Zaodu river is a provincial boundary river, and the is located in the transition zone of Sichuan Basin and the Yunnan Guizhou Plateau; with large drainage area, rich inflow and complex geological conditions. In order to better development and utilization of the water resource, Chongqing city started Zaodu prophase research of reservoir planning, including five aspects of hydrological, geological conditions, flooding programs, development programs and functional tasks. Study on the engineering geological conditions of reservoir is one of them. Based on the analysis of reservoir geological and hydrogeological conditions of left interstream block, for different geological rock group, it is divided into different hydrogeological unit to evaluat, refine evaluation methods, enrich the content of the evaluation. The results show, exists groundwater watershed in left interstream block, is far higher than the water level in the reservoir early. It will not leak to Songkan river after impound, which laid the foundation for the smooth development of the next phase of work.
Zaodu river is a provincial boundary river, and the is located in the transition zone of Sichuan Basin and the Yunnan Guizhou Plateau; with large drainage area, rich inflow and complex geological conditions. In order to better development and utilization of the water resource, Chongqing city started Zaodu prophase research of reservoir planning, including five aspects of hydrological, geological conditions, flooding programs, development programs and functional tasks. Study on the engineering geological conditions of reservoir is one of them. Based on the analysis of reservoir geological and hydrogeological conditions of left interstream block, for different geological rock group, it is divided into different hydrogeological unit to evaluat, refine evaluation methods, enrich the content of the evaluation. The results show, exists groundwater watershed in left interstream block, is far higher than the water level in the reservoir early. It will not leak to Songkan river after impound, which laid the foundation for the smooth development of the next phase of work.
2014, 22(s1): 249-257.
With the mining of coal resources reducing gradually and the imperative of water conservancy project construction, pressed coal mining is inevitable. In the rational exploitation of pressure coal resources condition, how to ensure the safe operation of water conservancy facilities is an important realistic problem.This paper takes Chongqing Jinfo Mountain canal of conservancy engineering as an example, using subsidence MSPS system to analyze the surface subsidence data under pressure mineral mining. This paper researches its impact on the canal of linear water conservancy project according to the result, and puts forward the deformation treatment and control measures finally. Through the research on the results of Chongqing Jinfo Mountain canal conservancy engineering department, linear water conservancy project pressure mining on the influence of water conservancy project is significant, the effect refers to deformity caused by presssure mining, while the water flowing fractured and caving zone have little impact on linear water coservancy project. It can eliminate the surface subsidence hazard by reducing the settlement joint spacing and increasing the canal height.
With the mining of coal resources reducing gradually and the imperative of water conservancy project construction, pressed coal mining is inevitable. In the rational exploitation of pressure coal resources condition, how to ensure the safe operation of water conservancy facilities is an important realistic problem.This paper takes Chongqing Jinfo Mountain canal of conservancy engineering as an example, using subsidence MSPS system to analyze the surface subsidence data under pressure mineral mining. This paper researches its impact on the canal of linear water conservancy project according to the result, and puts forward the deformation treatment and control measures finally. Through the research on the results of Chongqing Jinfo Mountain canal conservancy engineering department, linear water conservancy project pressure mining on the influence of water conservancy project is significant, the effect refers to deformity caused by presssure mining, while the water flowing fractured and caving zone have little impact on linear water coservancy project. It can eliminate the surface subsidence hazard by reducing the settlement joint spacing and increasing the canal height.
2014, 22(s1): 258-263.
The dam location of Mianhuatan hydropower station shows symmetrical cross-strait terrain, with high and steep mountain and narrow river, where there has RCC gravity dam whose height is more than hundred's meters. Underground houses are in the left bank. Dam foundation's main engineering geological problems are: dam foundation stability against sliding, leakage of dam foundation and high slope on both sides, etc. This article mainly introduces engineering treatnent measures for engineering geological problems, which would be a reference for similar project.
The dam location of Mianhuatan hydropower station shows symmetrical cross-strait terrain, with high and steep mountain and narrow river, where there has RCC gravity dam whose height is more than hundred's meters. Underground houses are in the left bank. Dam foundation's main engineering geological problems are: dam foundation stability against sliding, leakage of dam foundation and high slope on both sides, etc. This article mainly introduces engineering treatnent measures for engineering geological problems, which would be a reference for similar project.
2014, 22(s1): 264-270.
According to the characteristics of the geological disasters in the Three Gorges Reservoir of landslide, and taking Tanjiahe landslide in Reservoir for example, deformation characteristics and monitoring data of landslide are obtained through field geological survey. Combined with the engineering geological conditions of the landslide, reservoir level and rainfall, the two major factors influencing the landslide deformation are analyzed. Tanjiahe landslide is located on the right bank of the Yangtze River, and its deformation is more obvious since the Three Gorges Dam reservoir impounded, so the study of the relationship between Tanjiahe landslide deformation and reservoir level and rainfall and other predisposing factors is very necessary. Studies have shown that Tanjiahe landslide in the initial deformation stage, and the central and trailing edge deformed faster, showing a gradual passage landslide. The deformation of Tanjiahe landslide is more significant in the reservoir level and rainfall additive effect, reservoir water will soften the soil, resulting in uplift; and the rainfall will reduce the stabilizing force of slip zone, increase the total weight of the sliding body, increase the decline in power and forme of hydrostatic pressure. Especially when the reservoir level rises, landslide deformation rate show a sudden increases. Tanjiahe landslide is considered reservoir level elevation type slope. In this paper, combined with the Three Gorges Reservoir water level's changes and rainfall, the relationship between landslide deformation and the both factors is quantitatively analyzed, reasonablily, provide the basis for future landslide monitoring and warning.
According to the characteristics of the geological disasters in the Three Gorges Reservoir of landslide, and taking Tanjiahe landslide in Reservoir for example, deformation characteristics and monitoring data of landslide are obtained through field geological survey. Combined with the engineering geological conditions of the landslide, reservoir level and rainfall, the two major factors influencing the landslide deformation are analyzed. Tanjiahe landslide is located on the right bank of the Yangtze River, and its deformation is more obvious since the Three Gorges Dam reservoir impounded, so the study of the relationship between Tanjiahe landslide deformation and reservoir level and rainfall and other predisposing factors is very necessary. Studies have shown that Tanjiahe landslide in the initial deformation stage, and the central and trailing edge deformed faster, showing a gradual passage landslide. The deformation of Tanjiahe landslide is more significant in the reservoir level and rainfall additive effect, reservoir water will soften the soil, resulting in uplift; and the rainfall will reduce the stabilizing force of slip zone, increase the total weight of the sliding body, increase the decline in power and forme of hydrostatic pressure. Especially when the reservoir level rises, landslide deformation rate show a sudden increases. Tanjiahe landslide is considered reservoir level elevation type slope. In this paper, combined with the Three Gorges Reservoir water level's changes and rainfall, the relationship between landslide deformation and the both factors is quantitatively analyzed, reasonablily, provide the basis for future landslide monitoring and warning.
2014, 22(s1): 271-276.
This paper introduces the basic survey data, using the discrete element numerical simulation software UDEC to establish model, contrast slope under two kinds of transient storage. The stress field, strain field, strain(displacement) and the distribution of plastic zone were analyzed. At the same time calculation of the phreatic line slope water level change by using the software of GeoStudio Seep module, and used to calculate the stability coefficient changes in the water level dynamic state of Slope module based on the principle of coupled Sarma method. The results show that：the water before the local deformation, the front and back of large deformation after water storage, in front slope prone to buckling; water level rise in the overall stability of the slope was significantly decreased during the period, the overall stability of weak lower.
This paper introduces the basic survey data, using the discrete element numerical simulation software UDEC to establish model, contrast slope under two kinds of transient storage. The stress field, strain field, strain(displacement) and the distribution of plastic zone were analyzed. At the same time calculation of the phreatic line slope water level change by using the software of GeoStudio Seep module, and used to calculate the stability coefficient changes in the water level dynamic state of Slope module based on the principle of coupled Sarma method. The results show that：the water before the local deformation, the front and back of large deformation after water storage, in front slope prone to buckling; water level rise in the overall stability of the slope was significantly decreased during the period, the overall stability of weak lower.
2014, 22(s1): 277-283.
Liangshuijing landslide appeared dangerous condition during the first 175m experimental water storage in the Three Gorges Reservoir area, which attracted widespread attention of many geological disasters related departments and the community. On the basis of exploration, through the analysis of topography, geomorphology, material composition and geological structure, and combined with numerical simulation, the formation and reactivation mechanism of landslide is analyzed. Research show the following results,(1)Liangshuijing landslide is an old landslide formed by twice slip. It is an progressive landslide affected by the water soaking and water level changes, which induced by upper sliding body deformation dislocation in the running process of the Three Gorges Reservoir area.(2) At different stages of reservoir operation in the Three Gorges Reservoir area, the whole stability of landslide is reduced by influencing the different parts of the sliding zone.(3)Due to the thickness of the front slide body is large and lower block size is huge, contacts are formed between stone and slide bed. The sliding surface is easy to form a pillar role and locking effect in the middle relatively slow section, which make the landslide not instability.
Liangshuijing landslide appeared dangerous condition during the first 175m experimental water storage in the Three Gorges Reservoir area, which attracted widespread attention of many geological disasters related departments and the community. On the basis of exploration, through the analysis of topography, geomorphology, material composition and geological structure, and combined with numerical simulation, the formation and reactivation mechanism of landslide is analyzed. Research show the following results,(1)Liangshuijing landslide is an old landslide formed by twice slip. It is an progressive landslide affected by the water soaking and water level changes, which induced by upper sliding body deformation dislocation in the running process of the Three Gorges Reservoir area.(2) At different stages of reservoir operation in the Three Gorges Reservoir area, the whole stability of landslide is reduced by influencing the different parts of the sliding zone.(3)Due to the thickness of the front slide body is large and lower block size is huge, contacts are formed between stone and slide bed. The sliding surface is easy to form a pillar role and locking effect in the middle relatively slow section, which make the landslide not instability.
2014, 22(s1): 284-287.
This paper discusses the main research content and technology road of the assessment system of stone deterioration in stone monuments and theirs theories of the monitoring and early-warning from the research content of assessment system of stone deterioration, the research content of the monitoring and early-warning and the research feasibility of the theory of the monitoring and early-warning of stone deterioration. At the same time, this study is also an interdisciplinary research direction, which will become a new discipline growth point of engineering geology.
This paper discusses the main research content and technology road of the assessment system of stone deterioration in stone monuments and theirs theories of the monitoring and early-warning from the research content of assessment system of stone deterioration, the research content of the monitoring and early-warning and the research feasibility of the theory of the monitoring and early-warning of stone deterioration. At the same time, this study is also an interdisciplinary research direction, which will become a new discipline growth point of engineering geology.
2014, 22(s1): 288-291.
At present, there is not a systematic study for the relationship between the structure and shear strength. The author conducted consolidated drained triaxial shear tests for the slope loess of Jinnan, to study the correlation regular of the structural parameters and shear strength. The results show that under the combined effect of strength and water, when the pressure is small and water content is low, the structure is stronger, and the structure becomes weaker with the increasing of pressure and water content. When the structural is big, then the shear strength is also big.
At present, there is not a systematic study for the relationship between the structure and shear strength. The author conducted consolidated drained triaxial shear tests for the slope loess of Jinnan, to study the correlation regular of the structural parameters and shear strength. The results show that under the combined effect of strength and water, when the pressure is small and water content is low, the structure is stronger, and the structure becomes weaker with the increasing of pressure and water content. When the structural is big, then the shear strength is also big.
2014, 22(s1): 292-297.
In order to realize the creep properties of marble, the uniaxial creep experiment under a series of different loading time was carried out to the marble from heaven mountain in Chang'an County of Xi'an city by using RLW-1000G rock triaxial rheological meter, and the curve of creep test was identified by applying improved Nishihara model. The experiment shows that the instantaneous deformation, constant creep and accelerating creep in the axial deformation process of marble are more obvious, but the decelerating creep process is very short. As the time increasing, damage effect of marble increases under same load, which leads the strain increment enlarges. Marble composite rheological model is obtained by using the nonlinear viscous component to improve the the Nishihara model, which has gained good result, and possesses a certain guiding significance to realize the marble creep characteristics and construction of rock engineering.
In order to realize the creep properties of marble, the uniaxial creep experiment under a series of different loading time was carried out to the marble from heaven mountain in Chang'an County of Xi'an city by using RLW-1000G rock triaxial rheological meter, and the curve of creep test was identified by applying improved Nishihara model. The experiment shows that the instantaneous deformation, constant creep and accelerating creep in the axial deformation process of marble are more obvious, but the decelerating creep process is very short. As the time increasing, damage effect of marble increases under same load, which leads the strain increment enlarges. Marble composite rheological model is obtained by using the nonlinear viscous component to improve the the Nishihara model, which has gained good result, and possesses a certain guiding significance to realize the marble creep characteristics and construction of rock engineering.
2014, 22(s1): 298-304.
Although many models are proposed in landslide prediction in recently years, such as grey system, artificial neural net and time series analysis, the inverse-velocity method is still widely used and characterized by availability and simpleness. According to the movement histories of many landslides that occurred in a variety of materials in a range of settings, four movement patterns are observed evidently during acceleration phase：linear, fluctuant, asymptotic and instantaneous form. Deformation mechanism and movement characteristic of four movement patterns are also presented. The prediction results by the inverse-velocity method are illustrated by typical examples original from the published literature：(1)The inverse-velocity method is suitable for the linear form or fluctuant form that is associated with crack growth, and it can be used by plotting the inverse-velocity curve to predict failure time.(2)Due to ductile deformation in asymptotic form or sudden acceleration in instantaneous form, the method can not directly predict failure time in the two forms. However, the overall trend of landslide deformation is easier to interpret on the inverse-velocity plot.
Although many models are proposed in landslide prediction in recently years, such as grey system, artificial neural net and time series analysis, the inverse-velocity method is still widely used and characterized by availability and simpleness. According to the movement histories of many landslides that occurred in a variety of materials in a range of settings, four movement patterns are observed evidently during acceleration phase：linear, fluctuant, asymptotic and instantaneous form. Deformation mechanism and movement characteristic of four movement patterns are also presented. The prediction results by the inverse-velocity method are illustrated by typical examples original from the published literature：(1)The inverse-velocity method is suitable for the linear form or fluctuant form that is associated with crack growth, and it can be used by plotting the inverse-velocity curve to predict failure time.(2)Due to ductile deformation in asymptotic form or sudden acceleration in instantaneous form, the method can not directly predict failure time in the two forms. However, the overall trend of landslide deformation is easier to interpret on the inverse-velocity plot.
2014, 22(s1): 305-309.
This paper discusses the application of pseudo-static method based on collaborative analysis in foundation dynamic state. This paper analyzes the relationship between the shear modulus and shear strain state of rock and soil, and transforms the force of the seismic forces to equivalent inertia forces. For different types of rock and soil, the relationship between shear modulus G and shear strain Y is difference. Earthquake process which is unpredictable can not be simulated. Research shows that it can get a more accurate calculation result, if using a linear approach to simplifies the process of seismic force decay. In this paper, it simulates these relationships with FLAC-3D, and also verifies the feasibility by engineering example. At last, it provides a method to calculate the spring stiffness parameters set in the dynamic state.
This paper discusses the application of pseudo-static method based on collaborative analysis in foundation dynamic state. This paper analyzes the relationship between the shear modulus and shear strain state of rock and soil, and transforms the force of the seismic forces to equivalent inertia forces. For different types of rock and soil, the relationship between shear modulus G and shear strain Y is difference. Earthquake process which is unpredictable can not be simulated. Research shows that it can get a more accurate calculation result, if using a linear approach to simplifies the process of seismic force decay. In this paper, it simulates these relationships with FLAC-3D, and also verifies the feasibility by engineering example. At last, it provides a method to calculate the spring stiffness parameters set in the dynamic state.
2014, 22(s1): 310-314.
Karst collapse in the buried karst development area is a kind of common geological disaster, which brings great harm to local residents. This paper describes three kinds of methods which are field investigation, geophysical prospecting, drilling exploration to analyze the theory of karst development. These methods have been applied in field work. The results show that using a variety of methods under the condition of complex topography on karst collapse research is an effective and intuitive way.
Karst collapse in the buried karst development area is a kind of common geological disaster, which brings great harm to local residents. This paper describes three kinds of methods which are field investigation, geophysical prospecting, drilling exploration to analyze the theory of karst development. These methods have been applied in field work. The results show that using a variety of methods under the condition of complex topography on karst collapse research is an effective and intuitive way.
2014, 22(s1): 315-319.
Initiation is one of the key problems of debris flow study. It is studied in this paper by the Vane rheometer which is a new apparatus for debris flow study, by which the stain, strain rate and strain acceleration are analyzed. Based on those analysis, the debris flow initiation process is defined. The initiation characteristics will be demonstrated after the initiation process was distinguished from others by this definition. In turn the debris flow initiation mechanism will be explained by the experiment results which show that resistance decreases and pore water presses increase during the acceleration process. Initiation mechanism can be explained as the results of debris effect, shear thinning and liquefaction by the experiment results combined with others studies.
Initiation is one of the key problems of debris flow study. It is studied in this paper by the Vane rheometer which is a new apparatus for debris flow study, by which the stain, strain rate and strain acceleration are analyzed. Based on those analysis, the debris flow initiation process is defined. The initiation characteristics will be demonstrated after the initiation process was distinguished from others by this definition. In turn the debris flow initiation mechanism will be explained by the experiment results which show that resistance decreases and pore water presses increase during the acceleration process. Initiation mechanism can be explained as the results of debris effect, shear thinning and liquefaction by the experiment results combined with others studies.
2014, 22(s1): 320-325.
Boligou landslide located on the left bank of Boligou of Xuejiawan town, is a traction type landslide composed of landfill soil. Since several treatment measures had failed from 2009 to 2012,the investigations and regulation project for the landslide have to carry on again. This paper analyze the slope structures and deformation mechanism of the Boligou landslide through further exploration research：congenital condition for landslide formation is the natural slope shape changed by man-made; material basis for landslide deformation is special slope structure; inducing factors of landslide deformation are infiltration of surface water, the groundwater, and riverbed silt uplift and landslide slope toe excavation intensified deformation. On the basis of accurate analysis of landslide deformation mechanism, put forward engineering treatment measures and achieved success. At the same time, this paper analyzes the reason for the multiple treatment failure, and the root cause is paying less attention to the engineering geological investigation which leads to insufficient understanding of the deformation mechanism of landslide, especially erroneous judgement to the buried depth of the slip plane and ignoring the effect of groundwater on landslide. Under the condition of insufficient understanding of landslide deformation mechanism, blind implement the anti-sliding engineering resulted in multiple treatment measures failure. Therefore the important premise of radical cure landslide is to find out the engineering geological condition and landslide slope structure, and accurate analysis of the deformation mechanism and development process of the landslide by taking necessary means of engineering geological investigation.
Boligou landslide located on the left bank of Boligou of Xuejiawan town, is a traction type landslide composed of landfill soil. Since several treatment measures had failed from 2009 to 2012,the investigations and regulation project for the landslide have to carry on again. This paper analyze the slope structures and deformation mechanism of the Boligou landslide through further exploration research：congenital condition for landslide formation is the natural slope shape changed by man-made; material basis for landslide deformation is special slope structure; inducing factors of landslide deformation are infiltration of surface water, the groundwater, and riverbed silt uplift and landslide slope toe excavation intensified deformation. On the basis of accurate analysis of landslide deformation mechanism, put forward engineering treatment measures and achieved success. At the same time, this paper analyzes the reason for the multiple treatment failure, and the root cause is paying less attention to the engineering geological investigation which leads to insufficient understanding of the deformation mechanism of landslide, especially erroneous judgement to the buried depth of the slip plane and ignoring the effect of groundwater on landslide. Under the condition of insufficient understanding of landslide deformation mechanism, blind implement the anti-sliding engineering resulted in multiple treatment measures failure. Therefore the important premise of radical cure landslide is to find out the engineering geological condition and landslide slope structure, and accurate analysis of the deformation mechanism and development process of the landslide by taking necessary means of engineering geological investigation.
2014, 22(s1): 326-332.
This paper carrie out deep analysis and research on the regional geological structure, active fault, neotectonic movement characteristics and regional seismic activity of a low and intermediate-level radioactive waste disposal preselected area. And summarizes the basic rules and characteristics to find out that the neotectonic movement and seismic activity are relatively weak. On this basis, this paper carries out the regional crustal stability evaluation. The Low and intermediate-level radioactive waste disposal preselected area belong to relatively stable area. It can meet the requirements of low and intermediate-level radioactive waste disposal site.
This paper carrie out deep analysis and research on the regional geological structure, active fault, neotectonic movement characteristics and regional seismic activity of a low and intermediate-level radioactive waste disposal preselected area. And summarizes the basic rules and characteristics to find out that the neotectonic movement and seismic activity are relatively weak. On this basis, this paper carries out the regional crustal stability evaluation. The Low and intermediate-level radioactive waste disposal preselected area belong to relatively stable area. It can meet the requirements of low and intermediate-level radioactive waste disposal site.
2014, 22(s1): 333-338.
In order to explore the influence of salt content on strength of site soils, this paper is based on the laboratory test that join in two soluble salts with the gradient of 0.2% of NaCl and Na2SO4 to the desalination soil, and test the change of uniaxial compressive strength, tensile strength, elastic wave velocity and the ability to resist wind erosion of the soils which include particular and category saline in dry environment. The results show：under the condition of indoor environment, the existence of salt plays the role of a certain cement solidified to site soils, making the strength of the soil corresponding increase, and the cement solidification of sulfate is more than chlorine salt significantly to soils. The uniaxial compressive strength and tensile strength present the form of index increased; the elastic wave velocity in vertical and parallel direction of the suppression present increasing trend with the increasing of salt content; the loss of wind erosion increases with the increasing speed of carrying sand wind, and under the speed of 18ms-1 of carrying sand wind, the loss of wind erosion decreases with the increasing speed of carrying sand wind to salt samples. It showed the form of gradual damage.
In order to explore the influence of salt content on strength of site soils, this paper is based on the laboratory test that join in two soluble salts with the gradient of 0.2% of NaCl and Na2SO4 to the desalination soil, and test the change of uniaxial compressive strength, tensile strength, elastic wave velocity and the ability to resist wind erosion of the soils which include particular and category saline in dry environment. The results show：under the condition of indoor environment, the existence of salt plays the role of a certain cement solidified to site soils, making the strength of the soil corresponding increase, and the cement solidification of sulfate is more than chlorine salt significantly to soils. The uniaxial compressive strength and tensile strength present the form of index increased; the elastic wave velocity in vertical and parallel direction of the suppression present increasing trend with the increasing of salt content; the loss of wind erosion increases with the increasing speed of carrying sand wind, and under the speed of 18ms-1 of carrying sand wind, the loss of wind erosion decreases with the increasing speed of carrying sand wind to salt samples. It showed the form of gradual damage.
2014, 22(s1): 339-345.
This paper presents the method to calculate the rock porosity based on the microscopic images. It extracted the surface pore area, perimeter, morphological characteristics and other information of the different magnification SEM images of the deep red stratum sandstone based on the Image-Pro Plus(IPP).It calculated the rock porosity and fractal dimension. The results show that the deep red sandstone microscopic pore structure is fractal. The fractal dimension is between 1.8312～1.3302, and it has a decreasing trend with the magnification increases of the SEM images. The number of pore morphology and distribution uniformity in the SEM sight range is the main reason. The porosity calculation result has a little different based on different microscopic images. The conformity of porosity calculated by the images multiples of 300～600 and experimental measurement is quite high, which verifies the practical feasibility of this method. The methods and results of this paper provide a basis for the study of macroscopic damage and slake durability of red strata sandstone or other similar rock.
This paper presents the method to calculate the rock porosity based on the microscopic images. It extracted the surface pore area, perimeter, morphological characteristics and other information of the different magnification SEM images of the deep red stratum sandstone based on the Image-Pro Plus(IPP).It calculated the rock porosity and fractal dimension. The results show that the deep red sandstone microscopic pore structure is fractal. The fractal dimension is between 1.8312～1.3302, and it has a decreasing trend with the magnification increases of the SEM images. The number of pore morphology and distribution uniformity in the SEM sight range is the main reason. The porosity calculation result has a little different based on different microscopic images. The conformity of porosity calculated by the images multiples of 300～600 and experimental measurement is quite high, which verifies the practical feasibility of this method. The methods and results of this paper provide a basis for the study of macroscopic damage and slake durability of red strata sandstone or other similar rock.
2014, 22(s1): 346-351.
Take the preconstruction part of Guangle highway for an example, two plane strain finite element models of natural soft clay foundation and the foundation reinforced by pipe pile are established. With the analysis of construction stage, displacement field and stress field in the two models are obtained at each stage of the embankment construction process. Then comparative analysis between the two models can reveal the mechanism of reinforcement in a soft clay foundation provided by pipe pile. Results show that the integrality of soft clay foundation improves greatly after the application of pipe pile which takes big part of upper load, making soil taking less and then reducing the foundation deformation. In addition, around the center of the embankment, soil stress and deformation are larger than other areas. It is better to encrypt piles in this area and less in other areas from an economic point of view.
Take the preconstruction part of Guangle highway for an example, two plane strain finite element models of natural soft clay foundation and the foundation reinforced by pipe pile are established. With the analysis of construction stage, displacement field and stress field in the two models are obtained at each stage of the embankment construction process. Then comparative analysis between the two models can reveal the mechanism of reinforcement in a soft clay foundation provided by pipe pile. Results show that the integrality of soft clay foundation improves greatly after the application of pipe pile which takes big part of upper load, making soil taking less and then reducing the foundation deformation. In addition, around the center of the embankment, soil stress and deformation are larger than other areas. It is better to encrypt piles in this area and less in other areas from an economic point of view.
2014, 22(s1): 352-358.
Based on the deep analysis and summary of the principles of ecological slope protection, we present the key technology and problems of ecological slope protection engineering. In order to solve the problems, we proposed a new theory of water-control, which is rational use of water,then we designed a composite ecological slope protection plate and slope protection structure. To study its actual protective effect, an outdoor model test is carried out, which shows：(1)This new protective plate and protective plate structure have excellent structural stability, and the natural grading effect of the protection provide a more favorable platform and space for the grow of vegetation, which is beneficial to the vegetation's mechanical effect and hydrological effect of slope reinforcement, showing strong overall ecological slope effect; (2)Planting a variety of vegetation at the same time is beneficial to the survival and growth and facilitate the formation of ecological communities and long-term development, so that it can purify the air, beautify the environment, building green channel, to highlight its cultural landscape and social benefits; (3)By the way of outdoor model test, prove the combined effect of the new protective plates and protective structure with slope protection, afforestation and ecological balance directly, verify its feasibility, practicality and science. It can consider a large number of applications in practical engineering.
Based on the deep analysis and summary of the principles of ecological slope protection, we present the key technology and problems of ecological slope protection engineering. In order to solve the problems, we proposed a new theory of water-control, which is rational use of water,then we designed a composite ecological slope protection plate and slope protection structure. To study its actual protective effect, an outdoor model test is carried out, which shows：(1)This new protective plate and protective plate structure have excellent structural stability, and the natural grading effect of the protection provide a more favorable platform and space for the grow of vegetation, which is beneficial to the vegetation's mechanical effect and hydrological effect of slope reinforcement, showing strong overall ecological slope effect; (2)Planting a variety of vegetation at the same time is beneficial to the survival and growth and facilitate the formation of ecological communities and long-term development, so that it can purify the air, beautify the environment, building green channel, to highlight its cultural landscape and social benefits; (3)By the way of outdoor model test, prove the combined effect of the new protective plates and protective structure with slope protection, afforestation and ecological balance directly, verify its feasibility, practicality and science. It can consider a large number of applications in practical engineering.
2014, 22(s1): 359-364.
With the proposal of environment friendly tunnel porch concept and ecological and environmental design, plant roots to improve the stability of slope are used to protect original ecology of slopes. However, it is not clear about the effective and mechanism of reinforcing and resistance scouring from plant roots. Therefore, it is necessary to research deeply the action of slope for roots. In the paper, survey method in-site was conducted to the effect of rainfall on scouring with and without covering plants. The effective of plant is analyzed to resist to scouring. The resistant shearing strengthen parameters were measured by test in the experiment and FEM of reduced -strengthen method was used to simulate the action to reinforce of herbage. And shallow landslide was analyzed and evaluated plants roots. It is found that the plant root improves slide and scouring to its degree, especially in the district of gravel-cobble for least sand. At the same time, it can improve slope slide and decrease the polity according to different plant and soils. The conclusion can provide the reference to similar slope protection of design and construction and the conservation of slope during operation.
With the proposal of environment friendly tunnel porch concept and ecological and environmental design, plant roots to improve the stability of slope are used to protect original ecology of slopes. However, it is not clear about the effective and mechanism of reinforcing and resistance scouring from plant roots. Therefore, it is necessary to research deeply the action of slope for roots. In the paper, survey method in-site was conducted to the effect of rainfall on scouring with and without covering plants. The effective of plant is analyzed to resist to scouring. The resistant shearing strengthen parameters were measured by test in the experiment and FEM of reduced -strengthen method was used to simulate the action to reinforce of herbage. And shallow landslide was analyzed and evaluated plants roots. It is found that the plant root improves slide and scouring to its degree, especially in the district of gravel-cobble for least sand. At the same time, it can improve slope slide and decrease the polity according to different plant and soils. The conclusion can provide the reference to similar slope protection of design and construction and the conservation of slope during operation.
2014, 22(s1): 365-370.
Granite and its soil are widely dispersed over the southern part of China. There have been more and more granite soil high slopes along with the development of highways. Engineering geological properties of soil slope are different from the general soil slope for it's special formation process. There are important theoretical and practical significance to research such slopes. Monitoring is an effective method to research slope. It can identify the main controlling factors of slope deformation and failure and predict the long-term stability of the slope. The paper takes the example of a highway granite soil high slopes. The sliding zone is inferred here by the comprehensive analysis of appearance deformation monitoring data, inclinometer monitoring data and geological observation data. Then the slope deformation and failure characteristics are analyzed in details. The study shows that the optimal design and informational construction of high slopes can be achieved. It is also shown from the result that the hidden structural face in slope has very strong control effect on on slope stability.
Granite and its soil are widely dispersed over the southern part of China. There have been more and more granite soil high slopes along with the development of highways. Engineering geological properties of soil slope are different from the general soil slope for it's special formation process. There are important theoretical and practical significance to research such slopes. Monitoring is an effective method to research slope. It can identify the main controlling factors of slope deformation and failure and predict the long-term stability of the slope. The paper takes the example of a highway granite soil high slopes. The sliding zone is inferred here by the comprehensive analysis of appearance deformation monitoring data, inclinometer monitoring data and geological observation data. Then the slope deformation and failure characteristics are analyzed in details. The study shows that the optimal design and informational construction of high slopes can be achieved. It is also shown from the result that the hidden structural face in slope has very strong control effect on on slope stability.
2014, 22(s1): 371-376.
There are abundant rainfall and rich provenance in watershed of Jiaobangou in Dechang county, which are vulnerable to mountain torrents and debris flows. This paper assesses the risk of debris flows combined with the actual climate, hydrology, geology resources, population and economy. The hazard and vulnerability of the debris flow are 0.644 and 0.876,which belongs to highly dangerous, very highly vulnerable debris flow gully. The risk degree is 0.564,which is a debris flow ditch of high risk, it is vulnerable to large-scale debris flows. Based on the characteristics and evaluation results of Jiaobangou debris flow, propose comprehensive measures of combining monitoring and early warning with engineering remediation (rataining dam, blaeking net, solid bed dam, etc) to provide a theoretical support for disaster prevention and reduction of debris flows.
There are abundant rainfall and rich provenance in watershed of Jiaobangou in Dechang county, which are vulnerable to mountain torrents and debris flows. This paper assesses the risk of debris flows combined with the actual climate, hydrology, geology resources, population and economy. The hazard and vulnerability of the debris flow are 0.644 and 0.876,which belongs to highly dangerous, very highly vulnerable debris flow gully. The risk degree is 0.564,which is a debris flow ditch of high risk, it is vulnerable to large-scale debris flows. Based on the characteristics and evaluation results of Jiaobangou debris flow, propose comprehensive measures of combining monitoring and early warning with engineering remediation (rataining dam, blaeking net, solid bed dam, etc) to provide a theoretical support for disaster prevention and reduction of debris flows.
2014, 22(s1): 377-382.
The three commonly used methods, separate method, integral method and combined method can all be used to conduct numerical simulation of reinforced soil and reinforced concrete. The three methods are actually the same in the essence. In this paper, separate method, integral method and combined method are employed respectively to calculate a reinforced soil system and the results are compared. Two cases are considered for the combined method：one is considering the reinforcement being located at 1/3 of the height of the soil element, the other is assuming the reinforcement lying at 2/3 of the height. It is found that the results by different methods differ only in the range near the boundary of the computational domain, which is about two columns of elements. The results are almost the same deeper in the computational domain. The study is thought to be helpful in the application and selection of computational methods for reinforced soil.
The three commonly used methods, separate method, integral method and combined method can all be used to conduct numerical simulation of reinforced soil and reinforced concrete. The three methods are actually the same in the essence. In this paper, separate method, integral method and combined method are employed respectively to calculate a reinforced soil system and the results are compared. Two cases are considered for the combined method：one is considering the reinforcement being located at 1/3 of the height of the soil element, the other is assuming the reinforcement lying at 2/3 of the height. It is found that the results by different methods differ only in the range near the boundary of the computational domain, which is about two columns of elements. The results are almost the same deeper in the computational domain. The study is thought to be helpful in the application and selection of computational methods for reinforced soil.
2014, 22(s1): 383-389.
The shear and tensile properties of remolded loess and partially intact loess were investigated by using laboratory triaxial shear test and unconfined penetration tensile test, and the test results for three-dimensional surface fitting by Tablecuver 3D. The results indicated that tensile strength with water content and dry density showed a three-dimensional spiral surface, and similar with saturation, void ratio. The main factors affecting the tensile strength are water content and saturation, and the secondary factor are dry density and void ratio. Tensile strength with cohesion and internal friction angle show tangent concave slightly curled upward trend. Cohesion has a decisive influence on the tensile strength but the internal friction angle has little effect. The relation equation of tensile strength with cohesion and angle of internal friction tangent has general applicability after surface fitting discovery, and it's ease to estimate the tensile strength of loess in engineering practice.
The shear and tensile properties of remolded loess and partially intact loess were investigated by using laboratory triaxial shear test and unconfined penetration tensile test, and the test results for three-dimensional surface fitting by Tablecuver 3D. The results indicated that tensile strength with water content and dry density showed a three-dimensional spiral surface, and similar with saturation, void ratio. The main factors affecting the tensile strength are water content and saturation, and the secondary factor are dry density and void ratio. Tensile strength with cohesion and internal friction angle show tangent concave slightly curled upward trend. Cohesion has a decisive influence on the tensile strength but the internal friction angle has little effect. The relation equation of tensile strength with cohesion and angle of internal friction tangent has general applicability after surface fitting discovery, and it's ease to estimate the tensile strength of loess in engineering practice.
2014, 22(s1): 390-394.
Beichuan County, Sichuan Province, the 512 earthquake very severely affected counties,5.12 earthquake in Beichuan economic development into the lowest point in history, the annual flood season or after heavy rainfall have a great impact on the economy of Beichuan, only 2013 affected by heavy rainfall economic losses of several hundred million dollars, the question is whether you can deform before the disaster to disaster, there are certain block and protection is extremely important to avoid causing casualties and property loss. Based on this understanding, the survey found that in the actual collapse reached a preliminary preventive effect in the formation process. Before the collapse occurred were not set up protection works, takes place in the form of tall trees rely on a multi-row piles natural forest, succeeded in preventing the collapse of physical destruction of life and property of residents, and therefore causes the collapse of the county's analysis basis, not anti-sliding and rolling in the rockfall site, and given the small rockfall kinetic energy, analyzed and summarized on the site of a small bounce height planting protection works, on the one hand to protect the lives and property of residents, on the other hand can be green nature, such as can be achieved successfully serve two purposes.
Beichuan County, Sichuan Province, the 512 earthquake very severely affected counties,5.12 earthquake in Beichuan economic development into the lowest point in history, the annual flood season or after heavy rainfall have a great impact on the economy of Beichuan, only 2013 affected by heavy rainfall economic losses of several hundred million dollars, the question is whether you can deform before the disaster to disaster, there are certain block and protection is extremely important to avoid causing casualties and property loss. Based on this understanding, the survey found that in the actual collapse reached a preliminary preventive effect in the formation process. Before the collapse occurred were not set up protection works, takes place in the form of tall trees rely on a multi-row piles natural forest, succeeded in preventing the collapse of physical destruction of life and property of residents, and therefore causes the collapse of the county's analysis basis, not anti-sliding and rolling in the rockfall site, and given the small rockfall kinetic energy, analyzed and summarized on the site of a small bounce height planting protection works, on the one hand to protect the lives and property of residents, on the other hand can be green nature, such as can be achieved successfully serve two purposes.
2014, 22(s1): 395-399.
Through dating and large water immersion test on loess of under construction plant of Yuci Jili new energy automobiles and loess collapsibility test in Lliang airport, it is concluded that Q2 loess in some parts of Shanxi has strong collapsibity, large thickness and still with collapsibity under 600kPa pressure. It can put forward some suggestions for geotechnical engineering investigation and control.
Through dating and large water immersion test on loess of under construction plant of Yuci Jili new energy automobiles and loess collapsibility test in Lliang airport, it is concluded that Q2 loess in some parts of Shanxi has strong collapsibity, large thickness and still with collapsibity under 600kPa pressure. It can put forward some suggestions for geotechnical engineering investigation and control.
2014, 22(s1): 400-406.
The features of umbrella suction anchor foundation(USAF) are introduced, and the finite element model of USAF is established. Based on numerical simulation results, the foundation deformation of USAF,soil failure mode, the maximum shear stress area and the center of rotation of the anchor body are analyzed emphatically. A comparison has been made between the USAF model and conventional single cylinder suction anchor model and the results show that the umbrella suction anchor foundation(USAF)has obvious advantages in horizontal bearing capacity. It is very application prospect for USAF in offshore wind power engineering.
The features of umbrella suction anchor foundation(USAF) are introduced, and the finite element model of USAF is established. Based on numerical simulation results, the foundation deformation of USAF,soil failure mode, the maximum shear stress area and the center of rotation of the anchor body are analyzed emphatically. A comparison has been made between the USAF model and conventional single cylinder suction anchor model and the results show that the umbrella suction anchor foundation(USAF)has obvious advantages in horizontal bearing capacity. It is very application prospect for USAF in offshore wind power engineering.
2014, 22(s1): 407-412.
BIM technology is a new design approach, which implements the design change from two-dimensional to three-dimensional space, from static information to dynamic information technology development. On the basis of seeing a lot of domestic and international research literatures on supporting design of deep excavation engineering, summarize the design methods; analyze of the advantages and disadvantages of different design software and critical theoretical issues of design methods; propose the idea of BIM technology which application in the supporting design of deep excavation engineering; analyze of the key technical issues on BIM technology application in the supporting design of deep excavation engineering, which provide reference for relevant research.
BIM technology is a new design approach, which implements the design change from two-dimensional to three-dimensional space, from static information to dynamic information technology development. On the basis of seeing a lot of domestic and international research literatures on supporting design of deep excavation engineering, summarize the design methods; analyze of the advantages and disadvantages of different design software and critical theoretical issues of design methods; propose the idea of BIM technology which application in the supporting design of deep excavation engineering; analyze of the key technical issues on BIM technology application in the supporting design of deep excavation engineering, which provide reference for relevant research.
2014, 22(s1): 413-418.
Although analysis of slope stability based on artificial neural networks(ANN)has gained some significant results, it is basically limited in the stage of theory. So far it has not obtained a quite unified understanding about the selection and quantification of factors. Fault influence is ignored in most cases for it is hard to evaluate quantitatively. In this paper, Splintering Degree of Rock was taken into account in the ANN stability evaluation model of slope to evaluate the fault influence, which has definite geological basis. It is found that this method can solve the question of quantitative analysis for fault influence and improve the research of slope stability based on ANN.
Although analysis of slope stability based on artificial neural networks(ANN)has gained some significant results, it is basically limited in the stage of theory. So far it has not obtained a quite unified understanding about the selection and quantification of factors. Fault influence is ignored in most cases for it is hard to evaluate quantitatively. In this paper, Splintering Degree of Rock was taken into account in the ANN stability evaluation model of slope to evaluate the fault influence, which has definite geological basis. It is found that this method can solve the question of quantitative analysis for fault influence and improve the research of slope stability based on ANN.
2014, 22(s1): 419-425.
The changes of groundwater level, deep displacement and surface displacement were analyzed, based on the monitoring data obtained from Xiakou slope before and after the Lushan earthquake. The results show that：(1)the groundwater level rised abnormal before the earthquake, with the range of more than 1m. It reached the peak on the earthquake day. After the earthquake, it began to rapidly decline, at about 1.5m; (2)Landslide occurred a deep displacement of more than 1mm caused by the earthquake, then restore basic steady state. Landslide stability was analyzed by using the R/S analysis method. The Hurst index was significantly decreased in the April affected by the earthquake, indicating the stability of landslide decreased. But the Hurst index was greater than 0.5,indicating that the landslide was stable.
The changes of groundwater level, deep displacement and surface displacement were analyzed, based on the monitoring data obtained from Xiakou slope before and after the Lushan earthquake. The results show that：(1)the groundwater level rised abnormal before the earthquake, with the range of more than 1m. It reached the peak on the earthquake day. After the earthquake, it began to rapidly decline, at about 1.5m; (2)Landslide occurred a deep displacement of more than 1mm caused by the earthquake, then restore basic steady state. Landslide stability was analyzed by using the R/S analysis method. The Hurst index was significantly decreased in the April affected by the earthquake, indicating the stability of landslide decreased. But the Hurst index was greater than 0.5,indicating that the landslide was stable.
2014, 22(s1): 426-431.
Wenchuan County Futanggou on July 9, 2013 took place over 50 years of heavy rainfall, landslides broke out the next day, Wen Ying direct damage highways and bridges, causing interruption Aba lifeline out of Chengdu, disaster serious. From the basic characteristics of debris flow, formation conditions, analyzes the causes and trends mudslides, landslides control measures put forward the proposal to provide a scientific basis for timely finishing debris flows, to ensure the smooth flow of the lifeline provide reference for research-related debris flow.
Wenchuan County Futanggou on July 9, 2013 took place over 50 years of heavy rainfall, landslides broke out the next day, Wen Ying direct damage highways and bridges, causing interruption Aba lifeline out of Chengdu, disaster serious. From the basic characteristics of debris flow, formation conditions, analyzes the causes and trends mudslides, landslides control measures put forward the proposal to provide a scientific basis for timely finishing debris flows, to ensure the smooth flow of the lifeline provide reference for research-related debris flow.
2014, 22(s1): 432-438.
The article is based on field surveyed that Shangba landslide, Daguan county of Yunnan province, analysing of the basic characteristics and causes of the landslide. The landslide was the shape of tongue, lateral widest 230m, vertical longest 380m, the average thickness of the sliding body about 6m, body side slip about 52.44104m3,the whole landslide area can be divided into the overall decline area and traction crack area.(1)The overall decline in area：Length 120m, width 80m, the scarp was long 60m, high 7.5m after falling edge of the area, scarp occurrence 9268,it showed significant shed and stacking that the south side of the sliding body in the falling.(2)Traction crack area：Showed fecal dustpan, the narrow width, the horizontal width of 30meters, 60meters under the horizontal width, 70meters lengthwise. The most notable feature was the crack area formed on the slope of the level of scattered crack scarp and the formation of a crack groove in the north slope. Groove toward 68,lengthwise 20m, horizontal width 3～10m, depth 0.5～3m, with the passage of time, the groove may be further lengthened, widened and deepened under the action of rainfall.Shuanggou homologous geological structure and the negative topography, it provided favorable terrain conditions for the occurrence of landslide. By Yiliang earthquake affected, tensile fractures of abrupt slope provides a natural underpass for rainfall infiltration. Sustained rainfall infiltration, softed the slope surface structure, slope soil shear strength reduction, increased its own weight, decline in component increased, this caused a landslide occurred.
The article is based on field surveyed that Shangba landslide, Daguan county of Yunnan province, analysing of the basic characteristics and causes of the landslide. The landslide was the shape of tongue, lateral widest 230m, vertical longest 380m, the average thickness of the sliding body about 6m, body side slip about 52.44104m3,the whole landslide area can be divided into the overall decline area and traction crack area.(1)The overall decline in area：Length 120m, width 80m, the scarp was long 60m, high 7.5m after falling edge of the area, scarp occurrence 9268,it showed significant shed and stacking that the south side of the sliding body in the falling.(2)Traction crack area：Showed fecal dustpan, the narrow width, the horizontal width of 30meters, 60meters under the horizontal width, 70meters lengthwise. The most notable feature was the crack area formed on the slope of the level of scattered crack scarp and the formation of a crack groove in the north slope. Groove toward 68,lengthwise 20m, horizontal width 3～10m, depth 0.5～3m, with the passage of time, the groove may be further lengthened, widened and deepened under the action of rainfall.Shuanggou homologous geological structure and the negative topography, it provided favorable terrain conditions for the occurrence of landslide. By Yiliang earthquake affected, tensile fractures of abrupt slope provides a natural underpass for rainfall infiltration. Sustained rainfall infiltration, softed the slope surface structure, slope soil shear strength reduction, increased its own weight, decline in component increased, this caused a landslide occurred.
2014, 22(s1): 439-444.
Since there is a lack of a cost-effective in-situ measuring approches in the beach and neritic area of special sedimentary envrionment, we developed a new core penetration test system in shallow sea areas(CPtss),devided into the main equipment composed of penetration device and hydraulic device and the auxiliary equipment composed of air filling device, vacuum generator, and system control device. In the testing process, the main equipment, after being draged to the target location by ship, measures sediment strength by hydraulic drive way, and records the strength parameters. The CPtss has been applied to the modern subaqueous Yellow River delta, and the variation of tip resistance, lateral friction, and friction-resistance ratio with depth was obtained, and the bearing capacity of seabed was caculated basing on the obtained sediment strength parameters, and the stratigraphic characteristics was analyzed. The developed CPtss introduced in this paper, with the charateristics of stable and easy operation, and the capacity of continuous navigation test, has a good application prospect in engineering-geology investigation in the beach and shallow sea areas.
Since there is a lack of a cost-effective in-situ measuring approches in the beach and neritic area of special sedimentary envrionment, we developed a new core penetration test system in shallow sea areas(CPtss),devided into the main equipment composed of penetration device and hydraulic device and the auxiliary equipment composed of air filling device, vacuum generator, and system control device. In the testing process, the main equipment, after being draged to the target location by ship, measures sediment strength by hydraulic drive way, and records the strength parameters. The CPtss has been applied to the modern subaqueous Yellow River delta, and the variation of tip resistance, lateral friction, and friction-resistance ratio with depth was obtained, and the bearing capacity of seabed was caculated basing on the obtained sediment strength parameters, and the stratigraphic characteristics was analyzed. The developed CPtss introduced in this paper, with the charateristics of stable and easy operation, and the capacity of continuous navigation test, has a good application prospect in engineering-geology investigation in the beach and shallow sea areas.
BRIEF ANALYSIS ON THE DEVELOPMENT TREND OF DAGOU DEBRIS FLOW AND ITS PREVENTION AND CONTROL MEASURES
2014, 22(s1): 445-448.
Terrain and geomorphology, water source condition and loose solid materials in the debris flow gully are analyzed based on Dagou debris flow. Formation condition and initiation mechanisms of the debris flow gully are discussed, and the development trend of the debris flow gully is predicted. Finally, appropriate prevention and control measures are proposed according to its damage characteristics.
Terrain and geomorphology, water source condition and loose solid materials in the debris flow gully are analyzed based on Dagou debris flow. Formation condition and initiation mechanisms of the debris flow gully are discussed, and the development trend of the debris flow gully is predicted. Finally, appropriate prevention and control measures are proposed according to its damage characteristics.
2014, 22(s1): 449-453.
The beach profile measurement is the most direct access to the beach topography. This paper presents a convenient beach profile measurement method based on laser principle. Six survey lines were selected for field measurement at Tongan in Xiamen, and the measurement results were compared with those by the total station method. It shows the measurement accuracy is more than 96.7%, and a few large errors were induced by swings of laser rangefinder in wind. This measurement method is simple and rapid, and the measuring point distance can be arbitrarily set. The accumulative errors are not produced easily. It can be used in night and fog days, but not suitable for strong light and large wind weather.
The beach profile measurement is the most direct access to the beach topography. This paper presents a convenient beach profile measurement method based on laser principle. Six survey lines were selected for field measurement at Tongan in Xiamen, and the measurement results were compared with those by the total station method. It shows the measurement accuracy is more than 96.7%, and a few large errors were induced by swings of laser rangefinder in wind. This measurement method is simple and rapid, and the measuring point distance can be arbitrarily set. The accumulative errors are not produced easily. It can be used in night and fog days, but not suitable for strong light and large wind weather.
2014, 22(s1): 454-458.
The loess with high content of contains some sand grains, which often has high liquefaction potential, distributes widely in Loess Plateau and liquefaction is one of the crucial potential earthquake disasters in this region. Using the MTS810Teststar servo soil dynamic triaxial apparatus as test platform, this paper firstly studied the loess saturation by the head saturation method and libration liquefaction test for the saturated loess. Then discuss liquefaction mechanism and liquefaction characteristics of the loess under the continuous cycle dynamic loads, research the loess liquefaction discrimination criterion, analyse the loess liquefaction conditions and the impact factors. In addition, study the growth pattern of dynamic pore water pressure and dynamic strain under the action of the dynamic load of the loess. At the end as it provides the basic theory for the action of loess foundation and loess slope stability research under the effects of earthquake action.
The loess with high content of contains some sand grains, which often has high liquefaction potential, distributes widely in Loess Plateau and liquefaction is one of the crucial potential earthquake disasters in this region. Using the MTS810Teststar servo soil dynamic triaxial apparatus as test platform, this paper firstly studied the loess saturation by the head saturation method and libration liquefaction test for the saturated loess. Then discuss liquefaction mechanism and liquefaction characteristics of the loess under the continuous cycle dynamic loads, research the loess liquefaction discrimination criterion, analyse the loess liquefaction conditions and the impact factors. In addition, study the growth pattern of dynamic pore water pressure and dynamic strain under the action of the dynamic load of the loess. At the end as it provides the basic theory for the action of loess foundation and loess slope stability research under the effects of earthquake action.
2014, 22(s1): 459-465.
Glacier-related debris flow is the result of recession of glacier. With the recession of glacier, snow line rise, glacial ablation is intensified which increase the runoff, expand the glacier lake and thaw the frozen soil. Then under the influence of the steep terrain, with the abundant moraine came from glacier and loose material distributed along the river, it is easy to cause large-scale glacier-related debris flow. Modern glacier debris flow is mainly distributed in the high mountain which glacier retreat. Its distribution density influenced by the hydrothermal conditions physical properties and the type of glacier. Under the background of global warming, glacier-related debris flow break out more frequently. Glacier-related debris flow have always been ferocious and destructive. It break out suddenly on a horrific scale without any bodement and cause great damage to local people's life and property which aroused considerable public concern. So it is meaningful to figure out the evolution process and activity discipline of the glacier-related debris flow, to do some research upon precautionary measure, in order to reduce casualties and economic losses. This paper review the development in glacier-related debris flow research explore its time and space distribution reveal its evolution and and look forward prospective direction of the research.
Glacier-related debris flow is the result of recession of glacier. With the recession of glacier, snow line rise, glacial ablation is intensified which increase the runoff, expand the glacier lake and thaw the frozen soil. Then under the influence of the steep terrain, with the abundant moraine came from glacier and loose material distributed along the river, it is easy to cause large-scale glacier-related debris flow. Modern glacier debris flow is mainly distributed in the high mountain which glacier retreat. Its distribution density influenced by the hydrothermal conditions physical properties and the type of glacier. Under the background of global warming, glacier-related debris flow break out more frequently. Glacier-related debris flow have always been ferocious and destructive. It break out suddenly on a horrific scale without any bodement and cause great damage to local people's life and property which aroused considerable public concern. So it is meaningful to figure out the evolution process and activity discipline of the glacier-related debris flow, to do some research upon precautionary measure, in order to reduce casualties and economic losses. This paper review the development in glacier-related debris flow research explore its time and space distribution reveal its evolution and and look forward prospective direction of the research.
2014, 22(s1): 466-469.
At present domestic and foreign processing method of liquefaction is in a large number, such as the replacement method, dynamic compaction, gravel pile method, Zhen Chongsha method and compaction method. Each method has its scope and limitations. Compared with other methods in treatment of liquefiable ground, resonance method needs no aggregate replacement, convenient for construction, good strengthening effect, which has been widely used in abroad. By considering the site engineering, construction condition, economic and technological conditions, use cross wing resonance method to conduct liquefied foundation treatment.liquefaction evaluation on treated ground for different test methods. After processing the test, static cone penetration test and standard penetration test results show that, vibrating wing resonance method can effectively reinforce the liquefaction, liquefaction elimination; and has the advantages of simple equipment, convenient operation, high construction efficiency, low cost compared with other strengthening methods. The environmental impact of small vibration, and has a good prospect of application.
At present domestic and foreign processing method of liquefaction is in a large number, such as the replacement method, dynamic compaction, gravel pile method, Zhen Chongsha method and compaction method. Each method has its scope and limitations. Compared with other methods in treatment of liquefiable ground, resonance method needs no aggregate replacement, convenient for construction, good strengthening effect, which has been widely used in abroad. By considering the site engineering, construction condition, economic and technological conditions, use cross wing resonance method to conduct liquefied foundation treatment.liquefaction evaluation on treated ground for different test methods. After processing the test, static cone penetration test and standard penetration test results show that, vibrating wing resonance method can effectively reinforce the liquefaction, liquefaction elimination; and has the advantages of simple equipment, convenient operation, high construction efficiency, low cost compared with other strengthening methods. The environmental impact of small vibration, and has a good prospect of application.
2014, 22(s1): 470-475.
The tensile strength of the soil is smaller than the shear and compressive strength. Mechanical properties of soil under tensile state is often ignored by people, but in dam core wall, tensile huge buildings, ground fissures and landslide trailing edge cracks caused by some geotechnical engineering problems, such as people on the tensile strength ability put forward higher requirements. This article is based on a series of transformation of conventional triaxial apparatus, made to the stele tableland landslide of undisturbed loess with different confining pressure and moisture content by consolidated undrained tests, to obtain tensile strength parameters. On the basis of experiment. Based on the experimental results, under different confining pressure and moisture content of the relationship between tensile stress and strain are analyzed, and the tensile strength as the confining pressure and moisture content change curve, tensile strength parameters, so as to optimize the loess slump material parameter selection of calculation model.
The tensile strength of the soil is smaller than the shear and compressive strength. Mechanical properties of soil under tensile state is often ignored by people, but in dam core wall, tensile huge buildings, ground fissures and landslide trailing edge cracks caused by some geotechnical engineering problems, such as people on the tensile strength ability put forward higher requirements. This article is based on a series of transformation of conventional triaxial apparatus, made to the stele tableland landslide of undisturbed loess with different confining pressure and moisture content by consolidated undrained tests, to obtain tensile strength parameters. On the basis of experiment. Based on the experimental results, under different confining pressure and moisture content of the relationship between tensile stress and strain are analyzed, and the tensile strength as the confining pressure and moisture content change curve, tensile strength parameters, so as to optimize the loess slump material parameter selection of calculation model.
2014, 22(s1): 476-482.
As the eonomic development in China's Qinghai-Tibet Plateau and its surrounding region, it is imperative to construct national major strategic projects in high-altitude permafrost areas, the characteristics of whose distribution and engineering geological disasters have great effect on the construction. Based on available research data of and practical construction experiences on plateau permafrost currently, this paper summarizes the relationships between the distribution of high-altitude permafrost and macro controlling conditions(such as climate, altitude, et al.)as well as microscopic effecting factors(for example geology, topography, hydrology and vegetation, et al.).And a review of common geological disaster of permafrost and prevention measures of projects in plateau permafrost zone is conducted, with pointing out the shortcomings in present studies and the possible methods for high-altitude permafrost research.
As the eonomic development in China's Qinghai-Tibet Plateau and its surrounding region, it is imperative to construct national major strategic projects in high-altitude permafrost areas, the characteristics of whose distribution and engineering geological disasters have great effect on the construction. Based on available research data of and practical construction experiences on plateau permafrost currently, this paper summarizes the relationships between the distribution of high-altitude permafrost and macro controlling conditions(such as climate, altitude, et al.)as well as microscopic effecting factors(for example geology, topography, hydrology and vegetation, et al.).And a review of common geological disaster of permafrost and prevention measures of projects in plateau permafrost zone is conducted, with pointing out the shortcomings in present studies and the possible methods for high-altitude permafrost research.
2014, 22(s1): 483-487.
Landslide geologic hazards occur frequently in Huoshan, which is a Country in the Dabie Mountain range. This paper established an information data base of the landslide geological hazards by means of the GIS platform. The regularity of development and distribution of landslide around Huoshan Country is discussed. According to the distribution of landslide geological hazards in Huoshan County, combined with the engineering geological and hydrogeological conditions of the area, the human activity influence, et al., the formation conditions and the influencing factors of the landslide geological hazards in Huoshan Courtry are analyzed.
Landslide geologic hazards occur frequently in Huoshan, which is a Country in the Dabie Mountain range. This paper established an information data base of the landslide geological hazards by means of the GIS platform. The regularity of development and distribution of landslide around Huoshan Country is discussed. According to the distribution of landslide geological hazards in Huoshan County, combined with the engineering geological and hydrogeological conditions of the area, the human activity influence, et al., the formation conditions and the influencing factors of the landslide geological hazards in Huoshan Courtry are analyzed.
2014, 22(s1): 488-492.
In order to study drying shrinkage characteristics of loess in loess area surface, through the study of indoor test of volume shrinkage properties of saturated remolded loess after surface. The drying shrinkage volume were measured with liquid paraffin replacement method, analysis results show that, the whole process of shrinking the sample preparing remolded loess can be divided into three stages, namely the normal contraction stage, residual contraction phase and zero contraction phase. Most of the shrinkage occurs in the saturation stage specimen, the shrinkage degree not only in the longitudinal change, but also the obvious changes in the horizontal. Due to the contraction process will produce a series of non tectonic fissures in the Loess in vivo, change the mechanical properties of loess body in certain extent, which have significant influence on the engineering geology of Loess plateau. Finally, the variation characteristics of water on the specimen by drying shrinkage rate of loess soil, porosity, saturation and physical parameters such as volume shrinkage, and shrinkage characteristics curve unearthed.
In order to study drying shrinkage characteristics of loess in loess area surface, through the study of indoor test of volume shrinkage properties of saturated remolded loess after surface. The drying shrinkage volume were measured with liquid paraffin replacement method, analysis results show that, the whole process of shrinking the sample preparing remolded loess can be divided into three stages, namely the normal contraction stage, residual contraction phase and zero contraction phase. Most of the shrinkage occurs in the saturation stage specimen, the shrinkage degree not only in the longitudinal change, but also the obvious changes in the horizontal. Due to the contraction process will produce a series of non tectonic fissures in the Loess in vivo, change the mechanical properties of loess body in certain extent, which have significant influence on the engineering geology of Loess plateau. Finally, the variation characteristics of water on the specimen by drying shrinkage rate of loess soil, porosity, saturation and physical parameters such as volume shrinkage, and shrinkage characteristics curve unearthed.
2014, 22(s1): 493-497.
Engineering properties of soil will change after contaminated by organochlorine pesticides, and the pesticides also bring risk to the health of people and the environment. Recently, the research about pesticides contaminated soil mainly focused on the remediation of the site, seldom on its engineering properties. In this paper, organochlorine pesticide contaminated soils with different pesticide concentrations were made, unconfined compression strength(UCS),permeability test were done at curing time of 1 day, 7 days, 28 days, 56days and 90 days. The test results show that UCS of organochlorine pesticide contaminated soil decrease with the increase of pesticide concentration, UCS first increase then decrease with the increase of curing time, at the time of 56 days reached its peak; permeability coefficient of the contaminated soil decrease with the increase of pesticide concentration, increase with longer curing time.
Engineering properties of soil will change after contaminated by organochlorine pesticides, and the pesticides also bring risk to the health of people and the environment. Recently, the research about pesticides contaminated soil mainly focused on the remediation of the site, seldom on its engineering properties. In this paper, organochlorine pesticide contaminated soils with different pesticide concentrations were made, unconfined compression strength(UCS),permeability test were done at curing time of 1 day, 7 days, 28 days, 56days and 90 days. The test results show that UCS of organochlorine pesticide contaminated soil decrease with the increase of pesticide concentration, UCS first increase then decrease with the increase of curing time, at the time of 56 days reached its peak; permeability coefficient of the contaminated soil decrease with the increase of pesticide concentration, increase with longer curing time.
2014, 22(s1): 498-505.
The foundation settlement is a key problem that encountered when airports are built, and there is still no foundation differential settlement controlling standards for airport runway in our country and even in the world. The establishment of the runway foundation differential settlement controlling standard is of great significance for improving the airport design level, controlling project cost, and so on. Based on the relevant regulations of runway pavement smooth degree of International Civil Aviation Organization, and combined with two runway pavement settlement observation results of Shanghai Pudong airport, a foundation differential settlement controlling standard of airport runway is established in this paper. The differential settlement control curve of pavement construction period, differential settlement allowable value curve of operation period, and differential settlement limit value curve of operation period, which is maintenance standard, are respectively given in the differential settlement controlling standard, and safety area, warning area and the danger area are divided according to the three curve. The runway longitudinal differential settlement should be controlled in safety zone. This controlling standard has better applicability after confirmed in the two runway of Pudong airport, and this standard is also confirmed in runway damaged section of Wenshan airport, which proves the rationality of the maintenance standard curve. With the increase of the engineering examples, the controlling standard can also be applied to other types of settlement controlling after revised more perfectly.
The foundation settlement is a key problem that encountered when airports are built, and there is still no foundation differential settlement controlling standards for airport runway in our country and even in the world. The establishment of the runway foundation differential settlement controlling standard is of great significance for improving the airport design level, controlling project cost, and so on. Based on the relevant regulations of runway pavement smooth degree of International Civil Aviation Organization, and combined with two runway pavement settlement observation results of Shanghai Pudong airport, a foundation differential settlement controlling standard of airport runway is established in this paper. The differential settlement control curve of pavement construction period, differential settlement allowable value curve of operation period, and differential settlement limit value curve of operation period, which is maintenance standard, are respectively given in the differential settlement controlling standard, and safety area, warning area and the danger area are divided according to the three curve. The runway longitudinal differential settlement should be controlled in safety zone. This controlling standard has better applicability after confirmed in the two runway of Pudong airport, and this standard is also confirmed in runway damaged section of Wenshan airport, which proves the rationality of the maintenance standard curve. With the increase of the engineering examples, the controlling standard can also be applied to other types of settlement controlling after revised more perfectly.
2014, 22(s1): 506-510.
Test pile experiment for a certain project in Shanxi suggests qualities of piles do not meet standard requirement, as the inverse drilling technique is not suitable under this circumstance. Nonetheless, when rotating drilling is preferred due to thick layer of mud cakes and sediments involved in this project, standard requirement can be satisfied. This research indicates that selection of appropriate drilling technique is strictly based on work field conditions. By doing so the drilling capacity can be further increased due to the enlarged side and tip frictions. Bearing capacity of single pile can therefore be achieved.
Test pile experiment for a certain project in Shanxi suggests qualities of piles do not meet standard requirement, as the inverse drilling technique is not suitable under this circumstance. Nonetheless, when rotating drilling is preferred due to thick layer of mud cakes and sediments involved in this project, standard requirement can be satisfied. This research indicates that selection of appropriate drilling technique is strictly based on work field conditions. By doing so the drilling capacity can be further increased due to the enlarged side and tip frictions. Bearing capacity of single pile can therefore be achieved.
2014, 22(s1): 511-518.
The theory and methods of seafloor acoustics play a significant role in the development of marine engineering geology. Basing on the latest research progresses of the seafloor acoustical theory including seafloor sound proprogation model and seafloor sound reflection and scattering model and the seafloor acoustical methods including field investigation, in-situ observation, and laboratory experiments, this paper demonstrates the application and contribution of seafloor acoustics in marine engineering geology in the four aspects incuding marine engineering geological zoning, seabed sediment property inverting, field investigation of marine engineering geological hazards, and in-situ observation of marine engineering geological process. The summary on the close realationship between seafloor acoustics and marine engineering geology in this paper is being conducted to provide guidance to the application of seafloor acoustics in marine engineering geology in future.
The theory and methods of seafloor acoustics play a significant role in the development of marine engineering geology. Basing on the latest research progresses of the seafloor acoustical theory including seafloor sound proprogation model and seafloor sound reflection and scattering model and the seafloor acoustical methods including field investigation, in-situ observation, and laboratory experiments, this paper demonstrates the application and contribution of seafloor acoustics in marine engineering geology in the four aspects incuding marine engineering geological zoning, seabed sediment property inverting, field investigation of marine engineering geological hazards, and in-situ observation of marine engineering geological process. The summary on the close realationship between seafloor acoustics and marine engineering geology in this paper is being conducted to provide guidance to the application of seafloor acoustics in marine engineering geology in future.
2014, 22(s1): 519-523.
This paper describes the advantages and features of distributed optical fiber sensing technology. According to classifications of ancient Chinese architectures and monitoring requirements, it proposes monitoring program based on distributed optical fiber technology for ancient architectures, including the cable choice, the layout program and the installation process. The paper takes an ancient architecture as a case, and describes the practical application of distributed optical fiber sensing technology. It further proves that the distributed optical fiber sensing technology is a feasible and powerful technique for monitoring and health diagnosis of the ancient architectures.
This paper describes the advantages and features of distributed optical fiber sensing technology. According to classifications of ancient Chinese architectures and monitoring requirements, it proposes monitoring program based on distributed optical fiber technology for ancient architectures, including the cable choice, the layout program and the installation process. The paper takes an ancient architecture as a case, and describes the practical application of distributed optical fiber sensing technology. It further proves that the distributed optical fiber sensing technology is a feasible and powerful technique for monitoring and health diagnosis of the ancient architectures.
2014, 22(s1): 524-529.
The principle of distributed optical fiber sensing technology based on BOTDR is introduced in this paper. A mineral exploration hole in Huaibei was selected to do a field study on distributed optical fiber sensing technology for the monitoring of 10414mining face overburden deformation combined with coal mining process. Monitoring program selection, laying process of sensing fiber, data processing and analysis, etc. were included in this study. The coal mining overburden deformation law was analyzed. Experimental results show that：During the mining process, there is a fracture surface between the bottom of the upper igneous rocks and lower part of the rock, the separation occurs along the fracture surface in the lower part of the rock along with slip oblique to coalface. The bottom of the under igneous rock to lower rock is compressed by the action of gravity of the overlying rock, meanwhile the amount of deformation is increasing. Experimental results further validate that the mining overburden deformation monitoring method based on BOTDR is very effective, and provides a new monitoring technique for the safe and efficient coal mining.
The principle of distributed optical fiber sensing technology based on BOTDR is introduced in this paper. A mineral exploration hole in Huaibei was selected to do a field study on distributed optical fiber sensing technology for the monitoring of 10414mining face overburden deformation combined with coal mining process. Monitoring program selection, laying process of sensing fiber, data processing and analysis, etc. were included in this study. The coal mining overburden deformation law was analyzed. Experimental results show that：During the mining process, there is a fracture surface between the bottom of the upper igneous rocks and lower part of the rock, the separation occurs along the fracture surface in the lower part of the rock along with slip oblique to coalface. The bottom of the under igneous rock to lower rock is compressed by the action of gravity of the overlying rock, meanwhile the amount of deformation is increasing. Experimental results further validate that the mining overburden deformation monitoring method based on BOTDR is very effective, and provides a new monitoring technique for the safe and efficient coal mining.
2014, 22(s1): 530-535.
Based on the factor analysis, principal component analysis, and linear regression, the statistical analyses were done in 5 index of the loess physical properties which include the density, moisture content, porosity, liquid limit, plastic limit, and the initial subsidence pressure. Analysis shows that the subsidence pressure is moderately related to the density, which is low-alcohol related to the moisture content and porosity, and which is not related to plastic limit; the density is high related to porosity, and the moisture content, porosity and liquid limit had low-alcohol relation; the initial subsidence pressure was caused by multiple factors, the comprehensive statistics of physical and mechanical parameter can be used to determine the initial subsidence pressure.
Based on the factor analysis, principal component analysis, and linear regression, the statistical analyses were done in 5 index of the loess physical properties which include the density, moisture content, porosity, liquid limit, plastic limit, and the initial subsidence pressure. Analysis shows that the subsidence pressure is moderately related to the density, which is low-alcohol related to the moisture content and porosity, and which is not related to plastic limit; the density is high related to porosity, and the moisture content, porosity and liquid limit had low-alcohol relation; the initial subsidence pressure was caused by multiple factors, the comprehensive statistics of physical and mechanical parameter can be used to determine the initial subsidence pressure.
2014, 22(s1): 536-542.
Through analyzing the field data in the process of collection and arrangement of Darong landslide, failure mechanism conceptual model of Darong was established. In addition, its failure mechanism was studied through finite element method. It is concluded that the failure field in the left of slope saw a decrease in stability coefficient because of artificial landfill, as well as the change of seep conditions of groundwater. As a result, there are changes of stress field in failure field, creep in the middle-upper part of slope body and fracturing in the rear edge of slope, which caused stress concentration in toe of the slope. Finally, shear failure was happened in toe of the failure field caused by rainfall duration, which contributed to the landslide formation because of unstable failure of failure field.
Through analyzing the field data in the process of collection and arrangement of Darong landslide, failure mechanism conceptual model of Darong was established. In addition, its failure mechanism was studied through finite element method. It is concluded that the failure field in the left of slope saw a decrease in stability coefficient because of artificial landfill, as well as the change of seep conditions of groundwater. As a result, there are changes of stress field in failure field, creep in the middle-upper part of slope body and fracturing in the rear edge of slope, which caused stress concentration in toe of the slope. Finally, shear failure was happened in toe of the failure field caused by rainfall duration, which contributed to the landslide formation because of unstable failure of failure field.
2014, 22(s1): 543-550.
For the geological hazard in Yuzhong area, Chongqing such as deformation of slope, unstable rock collapse, slope, select 6 impact factors of geological disasters including the degree of development of geological hazard, topography, human engineering activities which damaged geological environment, geological structure, hydrogeological conditions and geotechnical properties. Use the method which combine FAHP that is based on AHP and geological disaster comprehensive evaluation index to evaluate and zone the geological disaster susceptible degree, and divide the Yuzhong area into 4 parts：high-prone areas, middle-prone areas, low-prone areas and non-prone areas. Their acreages are 1.67km2, 4.49km2, 0.83km2 and 17.12km2. The results are line with the actual situation. The results provide necessary and sufficient geological environment basis for geological disaster prevention zoing, urban planning, econonic development, ecological environmental protection and disaster prevention and mitigation in Yuzhong.
For the geological hazard in Yuzhong area, Chongqing such as deformation of slope, unstable rock collapse, slope, select 6 impact factors of geological disasters including the degree of development of geological hazard, topography, human engineering activities which damaged geological environment, geological structure, hydrogeological conditions and geotechnical properties. Use the method which combine FAHP that is based on AHP and geological disaster comprehensive evaluation index to evaluate and zone the geological disaster susceptible degree, and divide the Yuzhong area into 4 parts：high-prone areas, middle-prone areas, low-prone areas and non-prone areas. Their acreages are 1.67km2, 4.49km2, 0.83km2 and 17.12km2. The results are line with the actual situation. The results provide necessary and sufficient geological environment basis for geological disaster prevention zoing, urban planning, econonic development, ecological environmental protection and disaster prevention and mitigation in Yuzhong.
2014, 22(s1): 551-557.
Two major current issues of discrete element method(DEM)in rock and soil fields are proposed：1)mechanical relationship between discrete particles and macro model is not clear; 2)DEM requires huge computation, and it is low in efficiency. Theoretical studies and software development are carried out for the two issues. On the basis of the particle contact model of DEM,conversion formulas are introduced to build discrete element model with specified mechanical properties; a method for energy calculation of discrete element particles is also proposed. Based on these theoretical studies, a three-dimensional discrete element simulation system of rock and soil,MatDEM,has been developed from scratch. The software has good pre-processing and post-processing functions, with which result images and simulation demos can be generated automatically. Furthermore, the speed of DEM calculation is improved significantly using matrix calculation and high-performance GPU(Graphic Processing Unit) computation. MatDEM was used in the numerical simulation of hydraulic fracturing in a rock pore. Dynamic simulation of one million particles was completed in a single computer. The result indicates that micro-cracks tend to form along direction of maximum compressive stress and weak directions of anisotropic rock. Energy conversion curves show that elastic strain energy and kinetic energy were converted to heat during the simulation. However, the total energy always maintained unchanged, which indicates the conservation of energy in the discrete element system.
Two major current issues of discrete element method(DEM)in rock and soil fields are proposed：1)mechanical relationship between discrete particles and macro model is not clear; 2)DEM requires huge computation, and it is low in efficiency. Theoretical studies and software development are carried out for the two issues. On the basis of the particle contact model of DEM,conversion formulas are introduced to build discrete element model with specified mechanical properties; a method for energy calculation of discrete element particles is also proposed. Based on these theoretical studies, a three-dimensional discrete element simulation system of rock and soil,MatDEM,has been developed from scratch. The software has good pre-processing and post-processing functions, with which result images and simulation demos can be generated automatically. Furthermore, the speed of DEM calculation is improved significantly using matrix calculation and high-performance GPU(Graphic Processing Unit) computation. MatDEM was used in the numerical simulation of hydraulic fracturing in a rock pore. Dynamic simulation of one million particles was completed in a single computer. The result indicates that micro-cracks tend to form along direction of maximum compressive stress and weak directions of anisotropic rock. Energy conversion curves show that elastic strain energy and kinetic energy were converted to heat during the simulation. However, the total energy always maintained unchanged, which indicates the conservation of energy in the discrete element system.
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