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Editor Work2013 Vol. 21, No. 5
Previous Issue
2013, 21(5): 673-680.
Abstract
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This paper systematically analyzes the physical and chemical fields and their coupling in engineering geology. The fields are re-defined and the basic field concept is proposed accordingly to the engineering geological characteristics. The fields in engineering geology are classified as three categories, i.e. basic field, applied field and coupling field. Six fields are analyzed in detail. They are geological structural field, stress field, seepage field, temperature field, chemical field and deformation field. Then the categories of multi-field coupling are discussed and the multi-field coupling in engineering geology is studied. Finally the relative research topics are presented.
This paper systematically analyzes the physical and chemical fields and their coupling in engineering geology. The fields are re-defined and the basic field concept is proposed accordingly to the engineering geological characteristics. The fields in engineering geology are classified as three categories, i.e. basic field, applied field and coupling field. Six fields are analyzed in detail. They are geological structural field, stress field, seepage field, temperature field, chemical field and deformation field. Then the categories of multi-field coupling are discussed and the multi-field coupling in engineering geology is studied. Finally the relative research topics are presented.
2013, 21(5): 681-687.
The rock mass forming the dam foundation of Xiao Wan hydroelectric station during excavation revealed a series of deformation and fracture phenomena. It mainly behaved as a split plate and surface rock bursts, and cracks along the existing structure, expansion and dislocation, and so on. On the basis of the analyses of the above-mentioned phenomena, this paper studies the geological mechanic response of the rock mass due to the dam foundation excavation in the high in-situ stress environment. It is found that the rock mass deformation during excavation is mainly concentrated on the shallow surface of the dam foundation, which has time effect characteristics. According to analyses of deformation-destruction phenomenon and the study of deformation responses, the mechanism of deformation-destruction is understood. The mechanism applies to the excavation of the hard rock river bed of the dam foundation in the high in-situ stress environment. Shallow and superficial transformation result from the stress redistributed during down-cutting of river and unloading of excavation. Ultimately, it can be summarized that the deformation and fracture of river bed are a pressure rupture-unloading rebound model, and the pressure-rupture is the main type.
The rock mass forming the dam foundation of Xiao Wan hydroelectric station during excavation revealed a series of deformation and fracture phenomena. It mainly behaved as a split plate and surface rock bursts, and cracks along the existing structure, expansion and dislocation, and so on. On the basis of the analyses of the above-mentioned phenomena, this paper studies the geological mechanic response of the rock mass due to the dam foundation excavation in the high in-situ stress environment. It is found that the rock mass deformation during excavation is mainly concentrated on the shallow surface of the dam foundation, which has time effect characteristics. According to analyses of deformation-destruction phenomenon and the study of deformation responses, the mechanism of deformation-destruction is understood. The mechanism applies to the excavation of the hard rock river bed of the dam foundation in the high in-situ stress environment. Shallow and superficial transformation result from the stress redistributed during down-cutting of river and unloading of excavation. Ultimately, it can be summarized that the deformation and fracture of river bed are a pressure rupture-unloading rebound model, and the pressure-rupture is the main type.
2013, 21(5): 688-695.
The rock mass quality surrounding large underground cavern is affected by many factors. The rock classification is relatively complex. Using several rock classification methods synthetically is propitious to accurately determine the integrated category of the surrounding rocks. The classifications called RMR,Q,HC,BQ and RMi are used to classify the rocks of the main workshop on the basis of the experimental data and long-term field geological work. The workshop is the representative cavern of Dagangshan hydropower station. The study is conducted by means of regression analysis. The results show that among Q value, RMR value, and HC value there are exponential relations. The same circs also appears between RMi value and HC value, between RMi value and RMR value. The correlation coefficients for each of the pairs are 0.91, 0.82, 0.87, 0.94 respectively. Meanwhile, Q value and RMi value, RMR value and HC value have shown power relations, linear relations respectively. Accordingly, the correlation coefficients between each of them are 0.90 and 0.85 respectively. Between BQ value and HC value, the RMR value show linear relations, while between BQ value and Q value, the RMi value show exponential relation and logarithmic relation in sequence. The correlation coefficients between each of them are 0.49, 0.38, 0.38, and 0.40 respectively. The results also show that the correlation of RMR,Q,HC, and RMi classification are close related. They can complement and verify each other. They can be effectively applied to engineering practice. The BQ classification has poor correlation with the other four kinds of classification, so it is not very suitable to be used in the power station and similar projects.
The rock mass quality surrounding large underground cavern is affected by many factors. The rock classification is relatively complex. Using several rock classification methods synthetically is propitious to accurately determine the integrated category of the surrounding rocks. The classifications called RMR,Q,HC,BQ and RMi are used to classify the rocks of the main workshop on the basis of the experimental data and long-term field geological work. The workshop is the representative cavern of Dagangshan hydropower station. The study is conducted by means of regression analysis. The results show that among Q value, RMR value, and HC value there are exponential relations. The same circs also appears between RMi value and HC value, between RMi value and RMR value. The correlation coefficients for each of the pairs are 0.91, 0.82, 0.87, 0.94 respectively. Meanwhile, Q value and RMi value, RMR value and HC value have shown power relations, linear relations respectively. Accordingly, the correlation coefficients between each of them are 0.90 and 0.85 respectively. Between BQ value and HC value, the RMR value show linear relations, while between BQ value and Q value, the RMi value show exponential relation and logarithmic relation in sequence. The correlation coefficients between each of them are 0.49, 0.38, 0.38, and 0.40 respectively. The results also show that the correlation of RMR,Q,HC, and RMi classification are close related. They can complement and verify each other. They can be effectively applied to engineering practice. The BQ classification has poor correlation with the other four kinds of classification, so it is not very suitable to be used in the power station and similar projects.
2013, 21(5): 696-701.
This paper employs a sophisticated ring shear apparatus and conducts a series of fast rate ring shear tests to quantify the mechanical properties of Changchun silty clay. The tests are carried out under overconsolidated and fast ring shear conditions. The test results are obtained under different preconsolidation pressures, shear rates and normal stresses. The effects of stress history and shear rate on the shear resistance of the over-consolidated silty clay are examined and discussed. It is found that the preconsolidation pressures and shear rates exert remarkable influences on the peak shear strengths and the following post-peak reductions in strength. The shear strengths became greater when the preconsolidation pressures were higher. The test results at different shear rates show that if the OCR values are the same, both the peak strength and the post-peak strength reduction become greater as shear rate increases. The soils with high shear rate are prone to have the strain softening. The faster shear rate tests are more favorable to development of slip surface that lead to the ultimate stable shear strengths. The variations of shear resistance under fast shear rate in ring shear tests are mainly due to the structural changes in the shear zone, while the influence of pore water during fast shearing is negligible.
This paper employs a sophisticated ring shear apparatus and conducts a series of fast rate ring shear tests to quantify the mechanical properties of Changchun silty clay. The tests are carried out under overconsolidated and fast ring shear conditions. The test results are obtained under different preconsolidation pressures, shear rates and normal stresses. The effects of stress history and shear rate on the shear resistance of the over-consolidated silty clay are examined and discussed. It is found that the preconsolidation pressures and shear rates exert remarkable influences on the peak shear strengths and the following post-peak reductions in strength. The shear strengths became greater when the preconsolidation pressures were higher. The test results at different shear rates show that if the OCR values are the same, both the peak strength and the post-peak strength reduction become greater as shear rate increases. The soils with high shear rate are prone to have the strain softening. The faster shear rate tests are more favorable to development of slip surface that lead to the ultimate stable shear strengths. The variations of shear resistance under fast shear rate in ring shear tests are mainly due to the structural changes in the shear zone, while the influence of pore water during fast shearing is negligible.
2013, 21(5): 702-708.
A series of ring shear tests are carried out to study the shear behavior of two types of interfaces between Xigeda siltstone and concrete. The siltstone-concrete interfaces are made by pouring cement mortar on siltstone or compacting remolded soil and cement block. Results present the interface shear behavior in forms of shear stress-shear strain curves, vertical strain-shear strain curves and shear strength parameters. Results show that shear deformation causes normal deformation. As the normal stress increases, this effect is more significant. The maximum normal strain is up to 6.8%during the normal stress in 400kPa. In pouring form of interface, the contact surface damage occurs in the internal of siltstone for penetrating grout strengthened soil. In compacting type of interface, the parameters of friction were equivalent to the internal friction angle of siltstone. The cohesion could be ignored at the interface.
A series of ring shear tests are carried out to study the shear behavior of two types of interfaces between Xigeda siltstone and concrete. The siltstone-concrete interfaces are made by pouring cement mortar on siltstone or compacting remolded soil and cement block. Results present the interface shear behavior in forms of shear stress-shear strain curves, vertical strain-shear strain curves and shear strength parameters. Results show that shear deformation causes normal deformation. As the normal stress increases, this effect is more significant. The maximum normal strain is up to 6.8%during the normal stress in 400kPa. In pouring form of interface, the contact surface damage occurs in the internal of siltstone for penetrating grout strengthened soil. In compacting type of interface, the parameters of friction were equivalent to the internal friction angle of siltstone. The cohesion could be ignored at the interface.
2013, 21(5): 709-715.
The operation processes of many existing 3D geological modeling methods are often very cumbersome and complex. In order to reduce the labor intensity of technicians, meanwhile, to level up the intuition of the modeling process and to ensure the accuracy of the modeling results, this paper presents a 3D stratum modeling method. It is based on the GIS coordinating to AutoCAD and Google SketchUp. Firstly, the basic principles and the work flow are illustrated intuitively. Next, the process of borehole data processing and the construction of 3D geological scenes are elaborated in detail. Then, the key technologies are discussed in detail. They are related to drawing of stratum surface and boundary face and the construction and visualization of 3D geological stratum models. Finally, a 3D stratum model visualization prototype system has been implemented using C# for representing the constructed 3D stratum models. This system is based on SceneControl. The results of a series experiments show that the modeling method has the characteristics of easy to learn, powerful operability and process-oriented. It is a very practical 3D geological modeling method.
The operation processes of many existing 3D geological modeling methods are often very cumbersome and complex. In order to reduce the labor intensity of technicians, meanwhile, to level up the intuition of the modeling process and to ensure the accuracy of the modeling results, this paper presents a 3D stratum modeling method. It is based on the GIS coordinating to AutoCAD and Google SketchUp. Firstly, the basic principles and the work flow are illustrated intuitively. Next, the process of borehole data processing and the construction of 3D geological scenes are elaborated in detail. Then, the key technologies are discussed in detail. They are related to drawing of stratum surface and boundary face and the construction and visualization of 3D geological stratum models. Finally, a 3D stratum model visualization prototype system has been implemented using C# for representing the constructed 3D stratum models. This system is based on SceneControl. The results of a series experiments show that the modeling method has the characteristics of easy to learn, powerful operability and process-oriented. It is a very practical 3D geological modeling method.
2013, 21(5): 716-721.
Lan-Yu railway line has the Tertiary sandstone as the subgrade foundation. The sandstone has the characteristics of muddy weak cementation, unbound, low intensity, and shows water instability properties. It is very complicated in construction. Water content can increase significantly with the excavation of underground chamber. Plastic deformation and rheology, and stability of surrounding rock mass can rapidly vary, which can cause the sandstone structure damage, the inflows of water and sand, and other engineering geological problems. This paper uses the rock test, SEM and exploration of loose circle testing methods. It explores the groundwater seepage conditions and stress state of surrounding rock. The change due to rock microstructure change is the main mechanism of the softening and deformation.
Lan-Yu railway line has the Tertiary sandstone as the subgrade foundation. The sandstone has the characteristics of muddy weak cementation, unbound, low intensity, and shows water instability properties. It is very complicated in construction. Water content can increase significantly with the excavation of underground chamber. Plastic deformation and rheology, and stability of surrounding rock mass can rapidly vary, which can cause the sandstone structure damage, the inflows of water and sand, and other engineering geological problems. This paper uses the rock test, SEM and exploration of loose circle testing methods. It explores the groundwater seepage conditions and stress state of surrounding rock. The change due to rock microstructure change is the main mechanism of the softening and deformation.
2013, 21(5): 722-729.
The Xiluodu-Zhexi800 kV UHV DC transmission line passes through the Xiangxi area where the traffic is very inconvenient, the ground is undulating and the geological conditions are complex. Engineering drilling work carried out in this region is very difficult. Preliminary exploration data show that at the limestone area, karst development is strongly. Tower pad stability can face safety threats. At the sandstone district, the covering clay layer contains weathered debris. Ordinary twist drill is difficult to accurately determine the coverage layer thickness. In order to check the karst development situation and the bedrock surface depth, the ground penetrating radar was used to detect the strata after the pre-test demonstration. In addition to the ground penetrating radar detection on the ground, we also carried out the pile bottom detection in order to further investigate the karst development less than 5m under the bottom of the hole. Drilling and excavation results show that the ground penetrating radar can effectively detect the hidden karst, bedrock surface, weathered zone, fracture and fracture zone. It provides a scientific basis for reasonable choice tower bit and design foundation depth. It achieves a good application result.
The Xiluodu-Zhexi800 kV UHV DC transmission line passes through the Xiangxi area where the traffic is very inconvenient, the ground is undulating and the geological conditions are complex. Engineering drilling work carried out in this region is very difficult. Preliminary exploration data show that at the limestone area, karst development is strongly. Tower pad stability can face safety threats. At the sandstone district, the covering clay layer contains weathered debris. Ordinary twist drill is difficult to accurately determine the coverage layer thickness. In order to check the karst development situation and the bedrock surface depth, the ground penetrating radar was used to detect the strata after the pre-test demonstration. In addition to the ground penetrating radar detection on the ground, we also carried out the pile bottom detection in order to further investigate the karst development less than 5m under the bottom of the hole. Drilling and excavation results show that the ground penetrating radar can effectively detect the hidden karst, bedrock surface, weathered zone, fracture and fracture zone. It provides a scientific basis for reasonable choice tower bit and design foundation depth. It achieves a good application result.
2013, 21(5): 730-735.
Distribution of the spherically weathered granite(commonly known as the boulder)has a direct impact on the construction of urban rail transit project. It has important practical significance to detect spatial distribution of boulder accurately. This paper explores the distribution of granite boulders during subway construction. It combines with an instance of geophysical testing for detecting the distribution of granite boulders at the site of Shenzhen Metro Line 11.The distribution of granite boulders between two wells was studied with cross-hole ultra-density resistivity imaging. Test results can distinguish the difference of resistance between boulder and surrounding soil. Test results and field-proven drilling show that the geophysical method is satisfactory in detecting the spatial distribution of granite boulders in a certain degree, which provides guidance for further targeted investigation of the subway project and rich detection means of granite boulders.
Distribution of the spherically weathered granite(commonly known as the boulder)has a direct impact on the construction of urban rail transit project. It has important practical significance to detect spatial distribution of boulder accurately. This paper explores the distribution of granite boulders during subway construction. It combines with an instance of geophysical testing for detecting the distribution of granite boulders at the site of Shenzhen Metro Line 11.The distribution of granite boulders between two wells was studied with cross-hole ultra-density resistivity imaging. Test results can distinguish the difference of resistance between boulder and surrounding soil. Test results and field-proven drilling show that the geophysical method is satisfactory in detecting the spatial distribution of granite boulders in a certain degree, which provides guidance for further targeted investigation of the subway project and rich detection means of granite boulders.
2013, 21(5): 736-749.
On July 22, 2013,an earthquake of MS 6.6 occurred at the border area between Minxian and Zhangxian Counties, Gansu Province. The earthquake triggered many landslides of various types. The mainly types are small-scale falls, slides, and topples that occurred on loess scarps. There were also some deep-seated landslides, large-scale soil avalanches, and soil lateral spreads. In this paper, an inventory of landslides triggered by the earthquake is compiled based on partial field investigations and visual interpretation of high-resolution satellite images. Subsequently landslides spatial distribution analysis is also developed. It is indicated that the earthquake at least triggered 2330 landslides. Correlations of landslides with topographic, geological, and earthquake factors are developed on GIS platform. It is shown that the landslides were less affected by topographic factors but were more controlled by strata and lithology. Among of the 2330 landslides, 1401 landslides, occupied 60.13% of the total number with a maximum value of landslide number density of 22.78 landslides/km2,were occurred in areas of underlying bedrock of conglomerate and sandstone of Lower Permian strata of Paleogene(Eb). Correlation of PGA with landslides number density was obscure. Most of the landslides were concentrated in an elongated region, with 14km length and 5km width, parallel with seismogenic fault. A total of 1864 landslides, occupied 80% of the total landslide number, were occurred in the region. This indicates the landslides triggered by the earthquake were occurred close together. The event-based inventory of earthquake-triggered regional landslides in this article is an essential and core data for subsequent studies on earthquake-triggered landslides. Spatial distribution analysis of the landslides can provide scientific references for follow-up landslides and debris flow mitigation in earthquake struck area.
On July 22, 2013,an earthquake of MS 6.6 occurred at the border area between Minxian and Zhangxian Counties, Gansu Province. The earthquake triggered many landslides of various types. The mainly types are small-scale falls, slides, and topples that occurred on loess scarps. There were also some deep-seated landslides, large-scale soil avalanches, and soil lateral spreads. In this paper, an inventory of landslides triggered by the earthquake is compiled based on partial field investigations and visual interpretation of high-resolution satellite images. Subsequently landslides spatial distribution analysis is also developed. It is indicated that the earthquake at least triggered 2330 landslides. Correlations of landslides with topographic, geological, and earthquake factors are developed on GIS platform. It is shown that the landslides were less affected by topographic factors but were more controlled by strata and lithology. Among of the 2330 landslides, 1401 landslides, occupied 60.13% of the total number with a maximum value of landslide number density of 22.78 landslides/km2,were occurred in areas of underlying bedrock of conglomerate and sandstone of Lower Permian strata of Paleogene(Eb). Correlation of PGA with landslides number density was obscure. Most of the landslides were concentrated in an elongated region, with 14km length and 5km width, parallel with seismogenic fault. A total of 1864 landslides, occupied 80% of the total landslide number, were occurred in the region. This indicates the landslides triggered by the earthquake were occurred close together. The event-based inventory of earthquake-triggered regional landslides in this article is an essential and core data for subsequent studies on earthquake-triggered landslides. Spatial distribution analysis of the landslides can provide scientific references for follow-up landslides and debris flow mitigation in earthquake struck area.
2013, 21(5): 750-760.
On July 22, 2013a catastrophic earthquake with MS 6.6 occurred at the conjunction of Min and Zhang Counties, Dingxi City, Gansu Province, China. The seismic activities have caused a wide spread of damages to houses and infrastructures, and induced a series of potential hazards such as landslides, collapses and unstable slopes. This paper summarizes the types, distribution and major characteristics of the potential geohazards induced by the earthquake. Two indices including number of the slope geohazards and area development rate are used to analyse the relationship between the potential geohazards initiated by the earthquake and other controlling factors such as topographical, geological and seismic conditions in the epicenter area of Min County. The results show that:(1)The potential geohazards initiated by the earthquake are distributed in the area where elevations are in the range of 2200m to 2800m, slope gradient in 0～15,slope aspects in S,SW and W, and topographically at the middle parts of slopes; (2)The soft rocks are prone to landslide under seismic vibrations. The Devonian and Permian slate and limestone group produces about 50% of the geohazards in the whole earthquake affected area. The thick Neogene soft mudstone and sandstone group hosts the highest geohazards development rate. The main geohazards concentrate along or within 20km distance to the earthquake causative fault; (3)The correlation between individual geohazard scales and their distances to the epicenter and PGA are not significant. However, the general trend is obvious, as the development rate decreases with the increasing distance to the epicenter and increases with the increasing PGA.The greater the seismic intensity, the higher the probability of geohazards occurrence; (4)The closer to roads and river, the higher of the development rate of the geohazards, especially within the distance of 0～800m to the roads and 0～600m to the streams or rivers.
On July 22, 2013a catastrophic earthquake with MS 6.6 occurred at the conjunction of Min and Zhang Counties, Dingxi City, Gansu Province, China. The seismic activities have caused a wide spread of damages to houses and infrastructures, and induced a series of potential hazards such as landslides, collapses and unstable slopes. This paper summarizes the types, distribution and major characteristics of the potential geohazards induced by the earthquake. Two indices including number of the slope geohazards and area development rate are used to analyse the relationship between the potential geohazards initiated by the earthquake and other controlling factors such as topographical, geological and seismic conditions in the epicenter area of Min County. The results show that:(1)The potential geohazards initiated by the earthquake are distributed in the area where elevations are in the range of 2200m to 2800m, slope gradient in 0～15,slope aspects in S,SW and W, and topographically at the middle parts of slopes; (2)The soft rocks are prone to landslide under seismic vibrations. The Devonian and Permian slate and limestone group produces about 50% of the geohazards in the whole earthquake affected area. The thick Neogene soft mudstone and sandstone group hosts the highest geohazards development rate. The main geohazards concentrate along or within 20km distance to the earthquake causative fault; (3)The correlation between individual geohazard scales and their distances to the epicenter and PGA are not significant. However, the general trend is obvious, as the development rate decreases with the increasing distance to the epicenter and increases with the increasing PGA.The greater the seismic intensity, the higher the probability of geohazards occurrence; (4)The closer to roads and river, the higher of the development rate of the geohazards, especially within the distance of 0～800m to the roads and 0～600m to the streams or rivers.
2013, 21(5): 761-769.
A group of debris flow hazards occurred at Yinchanggou area on August 18,2012.This area was part of the epicenter region of Wenchuan earthquake. These debris flows greatly impacted the community of the Yinchanggou area and produced some casualties. This event also damaged many roads and other infrastructures. Debris flow hazards resulted from the coaction of the rainstorm and earthquake. Therefore,it is significant for better understanding of characters of debris flows to conduct the research on the mechanism in extreme seismic area. Field investigation and interpretations of aerial photographs were used to analyze variation of debris flow factors. This study demonstrates that loose mass generated by the collapse and landslides provided abundant materials for debris flows. The blockage of channel increased the scale of debris flow. Rainstorm like rapid triggering response pattern provided power for debris flow initiation. After discussing initiation,motion and deposition process,this study discovers that debris flows distributed like a band along fault and were very young. The trigger and control factors depend mainly on the rainfall condition. Besides,these hazards resulted from the coaction of debris flow itself and community.
A group of debris flow hazards occurred at Yinchanggou area on August 18,2012.This area was part of the epicenter region of Wenchuan earthquake. These debris flows greatly impacted the community of the Yinchanggou area and produced some casualties. This event also damaged many roads and other infrastructures. Debris flow hazards resulted from the coaction of the rainstorm and earthquake. Therefore,it is significant for better understanding of characters of debris flows to conduct the research on the mechanism in extreme seismic area. Field investigation and interpretations of aerial photographs were used to analyze variation of debris flow factors. This study demonstrates that loose mass generated by the collapse and landslides provided abundant materials for debris flows. The blockage of channel increased the scale of debris flow. Rainstorm like rapid triggering response pattern provided power for debris flow initiation. After discussing initiation,motion and deposition process,this study discovers that debris flows distributed like a band along fault and were very young. The trigger and control factors depend mainly on the rainfall condition. Besides,these hazards resulted from the coaction of debris flow itself and community.
2013, 21(5): 770-778.
This paper is based on the field survey and laboratory physical simulation in Kualiangzi landslide in Fengdian in Zhongjiang County. It finds that the slipping of the landslide can induce secondary tensile cracks or even through breakthrough. It combines the history of the landslide deformation with the force analysis. It demonstrates the generating process of tensile cracks and the breakthrough in sliding zone between tensile cracks, and puts forward the theory of multistage horizontal sliding in U-shaped slot model. It compares the study of multistage horizontally pushing landslide in Xuanhan county. It analyzes the formation mechanism and cause of multistage rift trough on rear edge. It compares the two different existing models of activating and motion styles, i.e.,pull-back style and push-forward style. It then establishes the geological mechanism models based on analysis of lithology, structural fissure development, inducing sliding water head height, velocity and water head height changes.
This paper is based on the field survey and laboratory physical simulation in Kualiangzi landslide in Fengdian in Zhongjiang County. It finds that the slipping of the landslide can induce secondary tensile cracks or even through breakthrough. It combines the history of the landslide deformation with the force analysis. It demonstrates the generating process of tensile cracks and the breakthrough in sliding zone between tensile cracks, and puts forward the theory of multistage horizontal sliding in U-shaped slot model. It compares the study of multistage horizontally pushing landslide in Xuanhan county. It analyzes the formation mechanism and cause of multistage rift trough on rear edge. It compares the two different existing models of activating and motion styles, i.e.,pull-back style and push-forward style. It then establishes the geological mechanism models based on analysis of lithology, structural fissure development, inducing sliding water head height, velocity and water head height changes.
2013, 21(5): 779-787.
The upper reaches of Yellow River northeastern Tibet Plateau(TP) is a high prone zone of geological disasters in western part of China. In the region, some large-scale and giant landslides are notable for their scales, complex formation mechanism, and serious destruction. In this paper, several different high resolution kinds of remote sensing data, such as QuickBird(QB),GeoEye, ZY-3,ZY-1 02C and Google earth, are used to be source data. They are combined with ways of field survey and remote sensing verification to carry out the spatial flatform of landslides and their distribution characteristics. (1)Remote sensing images of landslides characteristics are very obvious clearly in the study area. It is founded that there are 508 landslides. A majority of them are distributed in the Qunke-Jianzha Basin. (2)The spatial morphological flat patterns of landslides can be divided into eight categories. They are round-backed armchair-like and semi-elliptical pattern, dustpan pattern, dumbbell pattern, tongue pattern(including long tongue, rectangular, mat, stepped shape),saddle pattern, long-arc pattern and triangular pattern. The rock and soil types of landslides can be divided into four categories, loess landslide, mudstone landslide, semi consolidation diagenetic landslide and rock landslide. The number of mudstone landslides is the most. (3)The lengths and widths of landslide masses are mainly and respectively concentrated on 550m to 1500m and 600m to 1500m. They are extended directions by different polarizations. (4) The average elevation of landslides are mainly between 2400m to 2800m. The relative elevation differences of the front sheer opening and back trailing edge are concentrated on the 150m to 400m and around 750m. There are good linear relationships among the average slope angle, the relative elevation difference and the length of landslides mass. The research results can provide a basis evidence for serious geological disasters prevention and environment protection in study area.
The upper reaches of Yellow River northeastern Tibet Plateau(TP) is a high prone zone of geological disasters in western part of China. In the region, some large-scale and giant landslides are notable for their scales, complex formation mechanism, and serious destruction. In this paper, several different high resolution kinds of remote sensing data, such as QuickBird(QB),GeoEye, ZY-3,ZY-1 02C and Google earth, are used to be source data. They are combined with ways of field survey and remote sensing verification to carry out the spatial flatform of landslides and their distribution characteristics. (1)Remote sensing images of landslides characteristics are very obvious clearly in the study area. It is founded that there are 508 landslides. A majority of them are distributed in the Qunke-Jianzha Basin. (2)The spatial morphological flat patterns of landslides can be divided into eight categories. They are round-backed armchair-like and semi-elliptical pattern, dustpan pattern, dumbbell pattern, tongue pattern(including long tongue, rectangular, mat, stepped shape),saddle pattern, long-arc pattern and triangular pattern. The rock and soil types of landslides can be divided into four categories, loess landslide, mudstone landslide, semi consolidation diagenetic landslide and rock landslide. The number of mudstone landslides is the most. (3)The lengths and widths of landslide masses are mainly and respectively concentrated on 550m to 1500m and 600m to 1500m. They are extended directions by different polarizations. (4) The average elevation of landslides are mainly between 2400m to 2800m. The relative elevation differences of the front sheer opening and back trailing edge are concentrated on the 150m to 400m and around 750m. There are good linear relationships among the average slope angle, the relative elevation difference and the length of landslides mass. The research results can provide a basis evidence for serious geological disasters prevention and environment protection in study area.
2013, 21(5): 788-796.
Bedding rock landslide is a common slope disaster. The disaster strength of landslide is closely related to rock mass structure and terrain. It has important theoretical significance to assess its risk taking into consideration of the structure of the landslide. Firstly, the structural factors to the effect motion of bedding rock landslide are analyzed. The geological structure model of landside is put forward. Then, the basic law of the different structure landslide kinematics parameter is analyzed. The motion process of the different landslides that have different sliding body structures, slope angles and initial velocities is tested by the physical model. Lastly, the risk parameters of different structure bedding landslides is put forward by summarizing the tested data and risk calculation model of landslides. It indicates that:(1)Bedding rock landslide can be divided into three structures, similar granular, layer and block structure. When considering terrain, rock mass structure, slip surface, and layer structure can be divided into three subcategory in further; (2)Seven types of landslide structures are simulated by physical model test. The results manifest the following. The values of the terminal velocity of the active slide(vt),the influence range(L1) and impact strength(1) for the layer rock(Ⅱ), the blocky rock(Ⅳ), and the similar granular rock(Ⅶ) are ranked the highest, the second and the third; (3)The values of vt of the multilayer blocky rock with joints(Ⅴ),the multilayer rock(Ⅱ), and the multilayer blocky rock(Ⅳ) are ranked the highest, the second and the third. The rock Ⅳ has the largest of L1. The rock Ⅱ has the largest of 1;(4)The vulnerability strength of slide body for the blocky rock(Ⅳ and Ⅴ),the multilayer rock(Ⅱ and Ⅲ),the similar granular landslide(Ⅶ), and the single layer rock(Ⅰ) are ranked the No.1 to No.4 respectively. The strength indices of the back in accumulation area for(Ⅱ、Ⅲ and Ⅴ),the Ⅳ, Ⅰand Ⅶ are ranked the highest to the lowest, respectively. The strength index values of the front in the accumulation area for Ⅱ, Ⅴ, Ⅳ, Ⅲ and Ⅰ are ranked the highest to the lowest, respectively.
Bedding rock landslide is a common slope disaster. The disaster strength of landslide is closely related to rock mass structure and terrain. It has important theoretical significance to assess its risk taking into consideration of the structure of the landslide. Firstly, the structural factors to the effect motion of bedding rock landslide are analyzed. The geological structure model of landside is put forward. Then, the basic law of the different structure landslide kinematics parameter is analyzed. The motion process of the different landslides that have different sliding body structures, slope angles and initial velocities is tested by the physical model. Lastly, the risk parameters of different structure bedding landslides is put forward by summarizing the tested data and risk calculation model of landslides. It indicates that:(1)Bedding rock landslide can be divided into three structures, similar granular, layer and block structure. When considering terrain, rock mass structure, slip surface, and layer structure can be divided into three subcategory in further; (2)Seven types of landslide structures are simulated by physical model test. The results manifest the following. The values of the terminal velocity of the active slide(vt),the influence range(L1) and impact strength(1) for the layer rock(Ⅱ), the blocky rock(Ⅳ), and the similar granular rock(Ⅶ) are ranked the highest, the second and the third; (3)The values of vt of the multilayer blocky rock with joints(Ⅴ),the multilayer rock(Ⅱ), and the multilayer blocky rock(Ⅳ) are ranked the highest, the second and the third. The rock Ⅳ has the largest of L1. The rock Ⅱ has the largest of 1;(4)The vulnerability strength of slide body for the blocky rock(Ⅳ and Ⅴ),the multilayer rock(Ⅱ and Ⅲ),the similar granular landslide(Ⅶ), and the single layer rock(Ⅰ) are ranked the No.1 to No.4 respectively. The strength indices of the back in accumulation area for(Ⅱ、Ⅲ and Ⅴ),the Ⅳ, Ⅰand Ⅶ are ranked the highest to the lowest, respectively. The strength index values of the front in the accumulation area for Ⅱ, Ⅴ, Ⅳ, Ⅲ and Ⅰ are ranked the highest to the lowest, respectively.
2013, 21(5): 797-803.
Conventional anti-sliding piles have rectangular cross-sections. Their concrete in tension part cannot give the best performance due to concrete has low tensile strength. This paper redesigns the rectangular cross-sections by decreasing the tensile area and increasing the compressive area. The compression strength of the concrete can get better use. For that, the flexural capacity and flexural rigidity of the pile cross-sections can be enhanced. The soil arch effect can also be enhanced. This paper further presents the contrastive analysis of the numerical simulation of the piles with rectangular cross-section and special cross-section. The results confirm that the soil arch effect is enhanced. They also show that the pile with special cross-section has reduced the soil from the possibility of slip out. This article can provide theoretical reference for the anti-slide pile design.
Conventional anti-sliding piles have rectangular cross-sections. Their concrete in tension part cannot give the best performance due to concrete has low tensile strength. This paper redesigns the rectangular cross-sections by decreasing the tensile area and increasing the compressive area. The compression strength of the concrete can get better use. For that, the flexural capacity and flexural rigidity of the pile cross-sections can be enhanced. The soil arch effect can also be enhanced. This paper further presents the contrastive analysis of the numerical simulation of the piles with rectangular cross-section and special cross-section. The results confirm that the soil arch effect is enhanced. They also show that the pile with special cross-section has reduced the soil from the possibility of slip out. This article can provide theoretical reference for the anti-slide pile design.
2013, 21(5): 804-813.
This paper analyzes the NSFC proposals and grants of engineering geology in 2013.The total number of submitted proposals is reduced comparing with those in last years. The competitiveness of the proposals has been improved. The distribution of the applicants' ages tends to be reasonable. There are differences of funded ratios between different age groups. The talent team construction in future does not show well in engineering geology.
This paper analyzes the NSFC proposals and grants of engineering geology in 2013.The total number of submitted proposals is reduced comparing with those in last years. The competitiveness of the proposals has been improved. The distribution of the applicants' ages tends to be reasonable. There are differences of funded ratios between different age groups. The talent team construction in future does not show well in engineering geology.
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