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1
2012, 20(6): 909-915.
2012, 20(6): 909-915.
Abstract
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This paper presents an impulsive wave formula calculating system. It is based on geohazard impulsive wave formula and local head loss theory. . It takes into account on varied impulsive effect generated by varied landslides, decaying difference on varied region, frictional head loss and local head loss. It adopts many topography parameters. So its result is strongly objective. This paper takes impulsive wave generated by Gongjiafang for example and analyzes the impulsive wave. The results are close to the results of field investigation. The biggest impulsive wave height is 33.15 m. It is concluded that in the rapidly decaying area, the impulse wave has an average decrease of 4 m in wave amplitude within the distance of 100 m. While in the mildly decaying area, that figure is change to 0.11 m. Also it is found that there is an amplified decaying effect when the wave propagates from gorge to strath.
This paper presents an impulsive wave formula calculating system. It is based on geohazard impulsive wave formula and local head loss theory. . It takes into account on varied impulsive effect generated by varied landslides, decaying difference on varied region, frictional head loss and local head loss. It adopts many topography parameters. So its result is strongly objective. This paper takes impulsive wave generated by Gongjiafang for example and analyzes the impulsive wave. The results are close to the results of field investigation. The biggest impulsive wave height is 33.15 m. It is concluded that in the rapidly decaying area, the impulse wave has an average decrease of 4 m in wave amplitude within the distance of 100 m. While in the mildly decaying area, that figure is change to 0.11 m. Also it is found that there is an amplified decaying effect when the wave propagates from gorge to strath.
2
2020, 28(1): 69-76.
2020, 28(1): 69-76.
The variables of the soil-water characteristic curve(air-entry value, residual suction and slope at the inflection point) are very critical parameters in the strength theory, percolation theory and volume change behavior of unsaturated soil. It is often obtained by conventional graphical method, which is subjective and inaccurate. This study presents the methods for determining the variables of unimodal and bimodal SWCC based on VG model using the measured SWCC data of the four layers of undisturbed loess in Luochuan standard section. SWCC data were measured by filter paper method and best fitted using Van Genuchten's equation. Consequently the best fitting parameters were obtained, and the proposed methods were validated using the measured unimodal and bimodal SWCC data. The water evaporation test in the natural state was carried out. Then the evaporation residual saturation Srzf was determined according to the relationship between the mass moisture content and the evaporation time. According to the relative errors between Sr1, Sr2 and Srzf(Sr1 and Sr2 were acquired from the two methods for determining the residual state, respectively), the comparison was made between the two methods for determining the residual state. The results suggest that the proposed methods can produce reasonable variables and determine the residual state effectively related to the unimodal and bimodal SWCC.
The variables of the soil-water characteristic curve(air-entry value, residual suction and slope at the inflection point) are very critical parameters in the strength theory, percolation theory and volume change behavior of unsaturated soil. It is often obtained by conventional graphical method, which is subjective and inaccurate. This study presents the methods for determining the variables of unimodal and bimodal SWCC based on VG model using the measured SWCC data of the four layers of undisturbed loess in Luochuan standard section. SWCC data were measured by filter paper method and best fitted using Van Genuchten's equation. Consequently the best fitting parameters were obtained, and the proposed methods were validated using the measured unimodal and bimodal SWCC data. The water evaporation test in the natural state was carried out. Then the evaporation residual saturation Srzf was determined according to the relationship between the mass moisture content and the evaporation time. According to the relative errors between Sr1, Sr2 and Srzf(Sr1 and Sr2 were acquired from the two methods for determining the residual state, respectively), the comparison was made between the two methods for determining the residual state. The results suggest that the proposed methods can produce reasonable variables and determine the residual state effectively related to the unimodal and bimodal SWCC.
3
2020, 28(2): 189-201.
2020, 28(2): 189-201.
The problem of the Yellow River is reflected from the river, formed in the region, and rooted in the land. In light of the characteristics and challenges associated with geoscience problems in succeeding the high-quality development of the Yellow River Basin, this paper proposes the concept of so-called"livable Yellow River", which is consist of five core aspects in a systematic and scientific framework, namely the"Safe Yellow River", the"Green Yellow River", the"Ecological Yellow River", the"Harmonious Yellow River" and the"Intelligent Yellow River". The associated scientific connotation and major research contents of each aspect are illustrated in this paper. Specifically, (1)on the basis of the engineering geology, the"Safe Yellow River" aims to solve problems encountered in the geological surface process and the related disastrous impacts, so as to meet the geological safety requirements and build the Yellow River safety system; (2)on the basis of hydrogeology, the"Green Yellow River" focuses on the water cycle process and the related impacts on water and soil environment, thus constructs a green Yellow River system; (3)on the basis of the environmental geology, the "Ecological Yellow River" explores the evolution law of ecosystem and the related ecological barrier effect, and establishes an ecological Yellow River system; (4)on the basis of the resource geology, the "Harmonious Yellow River" studies the development mode of resource exploitation and people-land coordination in the Yellow River Basin, and builds a harmonious Yellow River system; (5)on the basis of the big data and information science, "Intelligent Yellow River" studies the geological information integration and intelligent decision-making platform of the Yellow River Basin, and constructs the intelligent Yellow River system. These five parts support and integrate each other to jointly solve the core and key issues of the livable Yellow River, so as to provide a scientific and technological support in ensuring the long-term stability of the Yellow River and promoting the high-quality development of the entire river basin, and ultimately forming a"Happiness Yellow River" that benefits the Chinese nation.
The problem of the Yellow River is reflected from the river, formed in the region, and rooted in the land. In light of the characteristics and challenges associated with geoscience problems in succeeding the high-quality development of the Yellow River Basin, this paper proposes the concept of so-called"livable Yellow River", which is consist of five core aspects in a systematic and scientific framework, namely the"Safe Yellow River", the"Green Yellow River", the"Ecological Yellow River", the"Harmonious Yellow River" and the"Intelligent Yellow River". The associated scientific connotation and major research contents of each aspect are illustrated in this paper. Specifically, (1)on the basis of the engineering geology, the"Safe Yellow River" aims to solve problems encountered in the geological surface process and the related disastrous impacts, so as to meet the geological safety requirements and build the Yellow River safety system; (2)on the basis of hydrogeology, the"Green Yellow River" focuses on the water cycle process and the related impacts on water and soil environment, thus constructs a green Yellow River system; (3)on the basis of the environmental geology, the "Ecological Yellow River" explores the evolution law of ecosystem and the related ecological barrier effect, and establishes an ecological Yellow River system; (4)on the basis of the resource geology, the "Harmonious Yellow River" studies the development mode of resource exploitation and people-land coordination in the Yellow River Basin, and builds a harmonious Yellow River system; (5)on the basis of the big data and information science, "Intelligent Yellow River" studies the geological information integration and intelligent decision-making platform of the Yellow River Basin, and constructs the intelligent Yellow River system. These five parts support and integrate each other to jointly solve the core and key issues of the livable Yellow River, so as to provide a scientific and technological support in ensuring the long-term stability of the Yellow River and promoting the high-quality development of the entire river basin, and ultimately forming a"Happiness Yellow River" that benefits the Chinese nation.
4
2020, 28(1): 158-168.
2020, 28(1): 158-168.
The NSFC proposals and grants of engineering geology field in 2019 are analyzed. The subjects include the engineering geological environment and disaster under the discipline of environmental geoscience and the engineering geology subordinate to the discipline of geology. The number of applications for funding projects in the field of engineering geology has increased rapidly, mainly due to the large increase in applications for General Program, Young Scientists Fund and Regional Science Funds. The number of applications for other types of fund programs remains stable. The statistics of the last ten years show that the peer-review referees well handled the peer-review scale on the proposals. The age structure of applicants for General Program tends to be younger, and that for the Youth Scientists Fund is reasonable. The field of engineering geology has been funded in a number of different project types, showing strong competitiveness.
The NSFC proposals and grants of engineering geology field in 2019 are analyzed. The subjects include the engineering geological environment and disaster under the discipline of environmental geoscience and the engineering geology subordinate to the discipline of geology. The number of applications for funding projects in the field of engineering geology has increased rapidly, mainly due to the large increase in applications for General Program, Young Scientists Fund and Regional Science Funds. The number of applications for other types of fund programs remains stable. The statistics of the last ten years show that the peer-review referees well handled the peer-review scale on the proposals. The age structure of applicants for General Program tends to be younger, and that for the Youth Scientists Fund is reasonable. The field of engineering geology has been funded in a number of different project types, showing strong competitiveness.
5
2019, 27(1): 202-207.
2019, 27(1): 202-207.
Coral reef is a kind of special geotechnical medium. From the perspective of engineering geology, it can be divided into two types:coral sandstone and coral reef limestone. This paper reviews the basic history of coral reef research for 30 years, focusing on the exploration and research results of the static mechanical properties, dynamic properties, low particle strength and other special mechanical properties of the coral sand soil and the engineering properties of the pile foundation. Taking the development and construction of coral reef islands in the South China Sea as a guide, more research scholars are called upon to join the research team of coral reefs to jointly promote the development of coral reef engineering geology.
Coral reef is a kind of special geotechnical medium. From the perspective of engineering geology, it can be divided into two types:coral sandstone and coral reef limestone. This paper reviews the basic history of coral reef research for 30 years, focusing on the exploration and research results of the static mechanical properties, dynamic properties, low particle strength and other special mechanical properties of the coral sand soil and the engineering properties of the pile foundation. Taking the development and construction of coral reef islands in the South China Sea as a guide, more research scholars are called upon to join the research team of coral reefs to jointly promote the development of coral reef engineering geology.
6
2020, 28(1): 10-18.
2020, 28(1): 10-18.
As an important parameter to characterize the fracture characteristics of rock mass,we characterize the fracture rate from the linear,surface and volumetric perspective. However,the available linear measurement method and statistical window method,which obtain the linear and surface fracture rate from 1-D or 2-D perspective,have the disadvantages of randomness of measurement results and limited application conditions. And the existing method of volumetric fracture rate also has some problems such as poor practical application and high cost. There is still a lack of easy-to-operate method to measure the rate of fissures in the field. Therefore,a new sphere method is proposed to measure volumetric fracture rate of rock mass in the field. Due to the unique tectonic and statistical regularity of the structure and diagenetic fissures,the sphere method observes each group of fracture occurrences from different directions. The development of the rock mass can be statistically inferred by measuring the developmental characteristics of each group of cracks on the limited exposed surface of rock mass. And its value can better reflect the development degree of the internal crack of the local rock mass. In addition,the spherical method can obtain the true value of the gap width and the gap spacing data along the normal direction of the fracture surface by using the patented instrument at the field. And the flatness of the exposed surface of the rock mass affect the measurement result hardly. Taking Dalongshan quarry in Anqing as the study area,field measurements of spheroid method show that the average volumetric fracture rate is 2.286% and the overall difference is concentrated in 1% ~4%. The method can realize rapid measurement on the basis of more convenient operation in the field. Combining the actual situation of the study area and the results of error analysis,the sphere method can reflect the degree of fracture development at each measurement point in the study area.
As an important parameter to characterize the fracture characteristics of rock mass,we characterize the fracture rate from the linear,surface and volumetric perspective. However,the available linear measurement method and statistical window method,which obtain the linear and surface fracture rate from 1-D or 2-D perspective,have the disadvantages of randomness of measurement results and limited application conditions. And the existing method of volumetric fracture rate also has some problems such as poor practical application and high cost. There is still a lack of easy-to-operate method to measure the rate of fissures in the field. Therefore,a new sphere method is proposed to measure volumetric fracture rate of rock mass in the field. Due to the unique tectonic and statistical regularity of the structure and diagenetic fissures,the sphere method observes each group of fracture occurrences from different directions. The development of the rock mass can be statistically inferred by measuring the developmental characteristics of each group of cracks on the limited exposed surface of rock mass. And its value can better reflect the development degree of the internal crack of the local rock mass. In addition,the spherical method can obtain the true value of the gap width and the gap spacing data along the normal direction of the fracture surface by using the patented instrument at the field. And the flatness of the exposed surface of the rock mass affect the measurement result hardly. Taking Dalongshan quarry in Anqing as the study area,field measurements of spheroid method show that the average volumetric fracture rate is 2.286% and the overall difference is concentrated in 1% ~4%. The method can realize rapid measurement on the basis of more convenient operation in the field. Combining the actual situation of the study area and the results of error analysis,the sphere method can reflect the degree of fracture development at each measurement point in the study area.
7
2018, 26(6): 1534-1551.
2018, 26(6): 1534-1551.
A large-scale landslide occurred in Baige village, at the border between Tibet Autonomous Region and Sichuan Province, on October 11, 2018. The sliding mass detached from a high-elevation mountain ridge, then dammed the Jinsha River impounding a barrier lake. This initial lake drained naturally. Afterwards, on November 3, a second landslide involved with a large mass of loose material from the first event blocked the river again, inducing a 50 m high dam and a barrier lake with a capacity of 500 million cubic meters. In order to alleviate the dangers of potential dam-breach flood, the artificial spillway was constructed allowing controlled breaching until November 13. However, downstream flooding still cause a major loss of property and damage, covering a large area of Sichuan Province and Yunnan Province. Extensive on-site investigation, combined with historical satellite images interpretation, InSAR monitoring, UAV aerial photography and ground deformation monitoring techniques, was conducted in this paper, to analyze the historical deformation of the study area and the evolutional characteristics of these two events. Based on that, the emergency measurements after each event have been developed, and the implementation of spillway was secured by monitoring and early-warning work at site. The successive landslides damming the Jinsha River presents a good example to study the emergency response and mitigation plan for similar cases in the future.
A large-scale landslide occurred in Baige village, at the border between Tibet Autonomous Region and Sichuan Province, on October 11, 2018. The sliding mass detached from a high-elevation mountain ridge, then dammed the Jinsha River impounding a barrier lake. This initial lake drained naturally. Afterwards, on November 3, a second landslide involved with a large mass of loose material from the first event blocked the river again, inducing a 50 m high dam and a barrier lake with a capacity of 500 million cubic meters. In order to alleviate the dangers of potential dam-breach flood, the artificial spillway was constructed allowing controlled breaching until November 13. However, downstream flooding still cause a major loss of property and damage, covering a large area of Sichuan Province and Yunnan Province. Extensive on-site investigation, combined with historical satellite images interpretation, InSAR monitoring, UAV aerial photography and ground deformation monitoring techniques, was conducted in this paper, to analyze the historical deformation of the study area and the evolutional characteristics of these two events. Based on that, the emergency measurements after each event have been developed, and the implementation of spillway was secured by monitoring and early-warning work at site. The successive landslides damming the Jinsha River presents a good example to study the emergency response and mitigation plan for similar cases in the future.
8
2020, 28(2): 360-374.
2020, 28(2): 360-374.
Monitoring and early warning have become the important means of preventing geohazards with rapid development in technology. A great deal of financial, manpower and physical resources have been adopted to work on landslide monitoring and early warning. However, some technical and managerial personnel have misunderstandings in landslide monitoring and early warning, which seriously affects the geohazards prevention and mitigation effects. Based on research results and lessons learned in practice over recent years, this paper discusses on some basic issues in terms of landslide monitoring and early warning. Main points include:(1)It is not that more monitoring locations and methods are better. The landslide monitoring plan should highlight pertinence, practicability and purpose, and its design and content mainly provide the basis for landslide early warning; (2)The occurrence for many landslides is sudden, and monitoring equipment with self-adaptive data acquisition function should be used to get entire deformation data, especially the accelerated creep stage, to guarantee scientific alert. (3)Monitoring is just a means to an end, while early warning is the end goal. Much attention should be paid on landslide early warning, like regional-scale meteorological early warning and slope-scale landslide early warning; (4)The commonly used early warning models with thresholds have a high rate of false and missing alarms. The study on statistical analysis of historical data, early warning models based on key parameters of deformation, underground water level and precipitation, become a high priority to improve the accuracy and practicality of landslide early warning.
Monitoring and early warning have become the important means of preventing geohazards with rapid development in technology. A great deal of financial, manpower and physical resources have been adopted to work on landslide monitoring and early warning. However, some technical and managerial personnel have misunderstandings in landslide monitoring and early warning, which seriously affects the geohazards prevention and mitigation effects. Based on research results and lessons learned in practice over recent years, this paper discusses on some basic issues in terms of landslide monitoring and early warning. Main points include:(1)It is not that more monitoring locations and methods are better. The landslide monitoring plan should highlight pertinence, practicability and purpose, and its design and content mainly provide the basis for landslide early warning; (2)The occurrence for many landslides is sudden, and monitoring equipment with self-adaptive data acquisition function should be used to get entire deformation data, especially the accelerated creep stage, to guarantee scientific alert. (3)Monitoring is just a means to an end, while early warning is the end goal. Much attention should be paid on landslide early warning, like regional-scale meteorological early warning and slope-scale landslide early warning; (4)The commonly used early warning models with thresholds have a high rate of false and missing alarms. The study on statistical analysis of historical data, early warning models based on key parameters of deformation, underground water level and precipitation, become a high priority to improve the accuracy and practicality of landslide early warning.
9
2017, 25(2): 455-462.
2017, 25(2): 455-462.
Simulations of landslide run-out can avoid the limit of experiment and instrumentation. It can observe the movement processes in detail. It is essential to the quantitative hazard assessment for landslide. for the simulation of landslide movement, the primary work is to establish a landslide model. Although the Particle Flow Code (PFC) is one of the most widely used program for landslide modeling, it is weak in the pre-processing of building the landslide model. This limits its application to landslide modeling. As for this, this paper illustrates the applicability, advantages and disadvantages of the Ball-Ball and Ball-Wall methods for model building. The way to determine the boundary of sliding mass and sliding bed is presented. It is based on the digital elevation map and the Brick filling method. It takes the earthquake-induced Red Rock Landslide as an example. Four steps are presented to build 2D & 3D landslide model with PFC.The four steps are obtaining topographic data, determining the boundary of both sliding mass and sliding bed, building the geometry of both sliding mass and sliding bed, filling the geometry with particles. By this way, the 2D and 3D landslide model can be easily and quickly built with PFC.The presented method will be helpful to the simulation of landslide movement with PFC.
Simulations of landslide run-out can avoid the limit of experiment and instrumentation. It can observe the movement processes in detail. It is essential to the quantitative hazard assessment for landslide. for the simulation of landslide movement, the primary work is to establish a landslide model. Although the Particle Flow Code (PFC) is one of the most widely used program for landslide modeling, it is weak in the pre-processing of building the landslide model. This limits its application to landslide modeling. As for this, this paper illustrates the applicability, advantages and disadvantages of the Ball-Ball and Ball-Wall methods for model building. The way to determine the boundary of sliding mass and sliding bed is presented. It is based on the digital elevation map and the Brick filling method. It takes the earthquake-induced Red Rock Landslide as an example. Four steps are presented to build 2D & 3D landslide model with PFC.The four steps are obtaining topographic data, determining the boundary of both sliding mass and sliding bed, building the geometry of both sliding mass and sliding bed, filling the geometry with particles. By this way, the 2D and 3D landslide model can be easily and quickly built with PFC.The presented method will be helpful to the simulation of landslide movement with PFC.
10
DEFORMATION ANALYSIS OF WODA VILLAGE OLD LANDSLIDE IN JINSHA RIVER BASIN USING SBAS-INSAR TECHNOLOGY
2020, 28(2): 384-393.
2020, 28(2): 384-393.
In recent years, unexpected high-level landslides have been increasing, resulting in adverse effects. This kind of geological hazard investigation is very difficult and concealed. It is difficult to solve the problem of disaster prevention and control by group survey and geological investigation alone. With the continuous improvement of the quality of radar remote sensing satellite data, the SBAS-InSAR technology in synthetic aperture Interferometric Radar(InSAR)provides a new technical approach for deformation detection of large-scale old landslides before disaster. The surface deformation of Wodacun landslide in Jinsha River Basin is monitored by SBAS-InSAR technology. The deformation results from March 30, 2017 to September 28, 2019 are obtained. Strong deformation area(Ⅰradar) and uniform deformation area(Ⅱradar) are delineated. The surface deformation rate, cumulative displacement trend and main crack deformation of the whole and local landslide in the revived area are analyzed. At the same time, the engineering geological survey and review are carried out on the spot. It is found that the resurrection and deformation signs of the old landslide are in good agreement with the interpretation results of the SBAS-InSAR technology. It is clear that the SBAS-InSAR technology has broad application prospects in the field of early warning and monitoring of geological disasters in complex mountain areas, and provides new ideas and references for monitoring and early warning similar to old landslides.
In recent years, unexpected high-level landslides have been increasing, resulting in adverse effects. This kind of geological hazard investigation is very difficult and concealed. It is difficult to solve the problem of disaster prevention and control by group survey and geological investigation alone. With the continuous improvement of the quality of radar remote sensing satellite data, the SBAS-InSAR technology in synthetic aperture Interferometric Radar(InSAR)provides a new technical approach for deformation detection of large-scale old landslides before disaster. The surface deformation of Wodacun landslide in Jinsha River Basin is monitored by SBAS-InSAR technology. The deformation results from March 30, 2017 to September 28, 2019 are obtained. Strong deformation area(Ⅰradar) and uniform deformation area(Ⅱradar) are delineated. The surface deformation rate, cumulative displacement trend and main crack deformation of the whole and local landslide in the revived area are analyzed. At the same time, the engineering geological survey and review are carried out on the spot. It is found that the resurrection and deformation signs of the old landslide are in good agreement with the interpretation results of the SBAS-InSAR technology. It is clear that the SBAS-InSAR technology has broad application prospects in the field of early warning and monitoring of geological disasters in complex mountain areas, and provides new ideas and references for monitoring and early warning similar to old landslides.
11
2020, 28(1): 169-177.
2020, 28(1): 169-177.
The Second International Symposium on Marine Engineering Geology(ISMEG 2019)was successfully held from 18 to 20 October 2019 in Dalian, China. It is a global academic symposium on marine engineering geology sponsored by IAEG's Commission for Marine Engineering Geology(C34) and hosted by the State Key Laboratory of Coastal and Offshore Engineering(Dalian University of Technology) under the framework of International Association for Engineering Geology and the Environment(IAEG). The theme of the symposium was the exploration of marine resources and marine engineering geology. The symposium had a total of 10 plenary reports, 21 keynote reports and 71 academic reports focused on seven special topics. They include engineering properties of marine soils, marine geological hazards and preventions, in-situ exploration, monitoring and physical modelling, hydrodynamics and environmental interaction, exploration of gas hydrate, offshore foundations and flow-structure-seabed interaction. As a platform of communication, sharing, cooperation and innovation for marine engineering geological researchers at home and abroad, the International Symposium on Marine Engineering Geology has been successfully held twice in China. The two symposiums affirmed the rapid development of marine engineering geological research in China, and moreover, put forward higher requirements for the high-level achievements and achievements transformation of marine engineering geological research in China.
The Second International Symposium on Marine Engineering Geology(ISMEG 2019)was successfully held from 18 to 20 October 2019 in Dalian, China. It is a global academic symposium on marine engineering geology sponsored by IAEG's Commission for Marine Engineering Geology(C34) and hosted by the State Key Laboratory of Coastal and Offshore Engineering(Dalian University of Technology) under the framework of International Association for Engineering Geology and the Environment(IAEG). The theme of the symposium was the exploration of marine resources and marine engineering geology. The symposium had a total of 10 plenary reports, 21 keynote reports and 71 academic reports focused on seven special topics. They include engineering properties of marine soils, marine geological hazards and preventions, in-situ exploration, monitoring and physical modelling, hydrodynamics and environmental interaction, exploration of gas hydrate, offshore foundations and flow-structure-seabed interaction. As a platform of communication, sharing, cooperation and innovation for marine engineering geological researchers at home and abroad, the International Symposium on Marine Engineering Geology has been successfully held twice in China. The two symposiums affirmed the rapid development of marine engineering geological research in China, and moreover, put forward higher requirements for the high-level achievements and achievements transformation of marine engineering geological research in China.
12
2019, 27(4): 760-765.
2019, 27(4): 760-765.
This paper presents a united expression of the compression lines of normal compressed clay, overconsolidated clay and sand by introducing a special vertical stress in single logarithmic coordinates. And then, based on the new expression and the concept of compression modulus, we obtain a calculation method for the compressive modulus of soil. Evolutionary laws of compressive modulus are presented and analyzed with the special vertical stress and compression index changing, respectively. Finally, comparisons with the test results and foundation settlement in engineering case indicate the rationality of this calculation method.
This paper presents a united expression of the compression lines of normal compressed clay, overconsolidated clay and sand by introducing a special vertical stress in single logarithmic coordinates. And then, based on the new expression and the concept of compression modulus, we obtain a calculation method for the compressive modulus of soil. Evolutionary laws of compressive modulus are presented and analyzed with the special vertical stress and compression index changing, respectively. Finally, comparisons with the test results and foundation settlement in engineering case indicate the rationality of this calculation method.
13
2020, 28(1): 141-148.
2020, 28(1): 141-148.
The Nairobi-Malabar railway project is an important part of the "northern corridor" of East Africa. It is the trunk line of economic development in landlocked African countries. The railway line works pass through the rift valley. The volcanic landform, the fault belt and the tension fracture are extremely development. However, there is a lack of research data on railway construction in the rift valley. To study railway lines through the rift valley, firstly, this paper introduces the topography, landform, development mechanism and regional fault distribution of the east African rift valley, and then formulates three major railway routes through the east African rift valley based on the economic control points along the railway. We had compared the terrain and landform traversed by the three major routes, the stratum, fault and ground fractures, the earthquake and volcanic developments, and the adverse geological disasters. Finally, the investment, advantages and disadvantages of each route had been compared, and finally the southern route scheme was recommended. The scheme of the route was approved and adopted by the Kenyan government. At present, the Nairobi Malaba railway is in trial operation, and the practice shows that the selection of the rift section of Nairobi-Malabar railway is relatively successful, which can provide reference for similar projects.
The Nairobi-Malabar railway project is an important part of the "northern corridor" of East Africa. It is the trunk line of economic development in landlocked African countries. The railway line works pass through the rift valley. The volcanic landform, the fault belt and the tension fracture are extremely development. However, there is a lack of research data on railway construction in the rift valley. To study railway lines through the rift valley, firstly, this paper introduces the topography, landform, development mechanism and regional fault distribution of the east African rift valley, and then formulates three major railway routes through the east African rift valley based on the economic control points along the railway. We had compared the terrain and landform traversed by the three major routes, the stratum, fault and ground fractures, the earthquake and volcanic developments, and the adverse geological disasters. Finally, the investment, advantages and disadvantages of each route had been compared, and finally the southern route scheme was recommended. The scheme of the route was approved and adopted by the Kenyan government. At present, the Nairobi Malaba railway is in trial operation, and the practice shows that the selection of the rift section of Nairobi-Malabar railway is relatively successful, which can provide reference for similar projects.
14
2020, 28(1): 29-38.
2020, 28(1): 29-38.
Accurately evaluation of brittleness characteristics of granite under different water content is of great significance to rock mass stability evaluation. The existing rock brittleness evaluation indices are summarized. The indices based on stress-strain curve are analyzed in detail. The brittleness of granite decreases with the increase of water content under uniaxial compression,but experiment results show that the indices which based on the stress-strain curve are difficult to accurately reflect the brittleness characteristics of granite under different water contents. So a new brittleness index Bd is proposed and can fully reflect the whole process of granite deformation and failure. Considering the whole process stress-strain curve and the post peak failure time,the new index Bd uses the peak strain to characterize the pre-peak brittleness characteristics and uses the post peak stress drop rate and the post peak strain growth rate to characterize the post-peak brittleness characteristics. It is proved by experiments that the index Bd can accurately reflect the trend that the granite brittleness decreases with the increase of water content. The new index Bd has superiority over the other brittleness indices. The research results can provide some references and help to enrich and improve the rock brittle characteristics evaluation methods.
Accurately evaluation of brittleness characteristics of granite under different water content is of great significance to rock mass stability evaluation. The existing rock brittleness evaluation indices are summarized. The indices based on stress-strain curve are analyzed in detail. The brittleness of granite decreases with the increase of water content under uniaxial compression,but experiment results show that the indices which based on the stress-strain curve are difficult to accurately reflect the brittleness characteristics of granite under different water contents. So a new brittleness index Bd is proposed and can fully reflect the whole process of granite deformation and failure. Considering the whole process stress-strain curve and the post peak failure time,the new index Bd uses the peak strain to characterize the pre-peak brittleness characteristics and uses the post peak stress drop rate and the post peak strain growth rate to characterize the post-peak brittleness characteristics. It is proved by experiments that the index Bd can accurately reflect the trend that the granite brittleness decreases with the increase of water content. The new index Bd has superiority over the other brittleness indices. The research results can provide some references and help to enrich and improve the rock brittle characteristics evaluation methods.
15
2020, 28(1): 111-121.
2020, 28(1): 111-121.
Most of the loess landslides induced by irrigation own obvious sudden characteristics. The deformation and displacement during slope failure process are small and the time of duration is short, which is of great risk. Due to such loess landslides undergo a short time in accelerated deformation stage, it is difficult for traditional monitoring methods, such as GNSS system and crack gauge, to obtain complete monitoring data in accelerated deformation stage and to predict the sudden landslide occurrence. With respect to this problem, a self-adaptive frequency conversion acquisition monitoring method is designed to monitor the deformation of sudden loess landslides, which adjust automatically the frequency sampling according to the speed of landslide deformation. To meet the needs for risk mitigation and management of slope sudden failure, it is of practical significance to develop a self-adaptive frequency conversion acquisition monitoring method and establish a real-time automatic early warning system. The new artificial intelligence by the authors' institute can obtain entire monitoring data in accelerated deformation stage and to predict the sudden failure occurrence time. Taking deformation rate threshold and the improved tangent angle as the early warning parameters of comprehensive warning model, a four-level early warning criterion is established. The real-time automatic early warning of the landslide is realized through the self-developed "real-time monitoring and early warning system of geological hazards". The early warning information is released in the local group defense information platform, which provides a direct gauge for disaster prevention and emergency avoidance. Since 2017, it has been successfully warned six times of loess slope sudden failure on the Heifangtai terrace, which avoided heavy casualties and achieved remarkable disaster prevention and mitigation effect.
Most of the loess landslides induced by irrigation own obvious sudden characteristics. The deformation and displacement during slope failure process are small and the time of duration is short, which is of great risk. Due to such loess landslides undergo a short time in accelerated deformation stage, it is difficult for traditional monitoring methods, such as GNSS system and crack gauge, to obtain complete monitoring data in accelerated deformation stage and to predict the sudden landslide occurrence. With respect to this problem, a self-adaptive frequency conversion acquisition monitoring method is designed to monitor the deformation of sudden loess landslides, which adjust automatically the frequency sampling according to the speed of landslide deformation. To meet the needs for risk mitigation and management of slope sudden failure, it is of practical significance to develop a self-adaptive frequency conversion acquisition monitoring method and establish a real-time automatic early warning system. The new artificial intelligence by the authors' institute can obtain entire monitoring data in accelerated deformation stage and to predict the sudden failure occurrence time. Taking deformation rate threshold and the improved tangent angle as the early warning parameters of comprehensive warning model, a four-level early warning criterion is established. The real-time automatic early warning of the landslide is realized through the self-developed "real-time monitoring and early warning system of geological hazards". The early warning information is released in the local group defense information platform, which provides a direct gauge for disaster prevention and emergency avoidance. Since 2017, it has been successfully warned six times of loess slope sudden failure on the Heifangtai terrace, which avoided heavy casualties and achieved remarkable disaster prevention and mitigation effect.
16
2020, 28(3): 541-556.
2020, 28(3): 541-556.
A large scale of mountain rock avalanche occurred at about 20:40 on July 23, 2019 in Jichang town, Shuicheng county, Guizhou Province. The rock mass moved down and scraped the original loose deposits and finally formed deposits of 191.2×104 m3. It destroyed parts of Pingdi Village, resulted in the death of 43 persons and missing of 9 persons. Based on site investigation, unmanned aerial vehicle(UAV)photography and other technologies, this paper provides a detailed description on the characteristics and a comprehensive analysis on the dynamic process and failure mechanism of the long runout landslide. And there is still a risk that the accumulation of the landslide can be translated into debris flow during rainfall. The results indicate that the special geometry of the source area, the weathered and shattered basalt mass and favorable combination of discontinuities are the internal cause factors for sliding. The rainfall infiltrating and its softening effect, and the road construction cut-slope are the external cause factors for the landslide. There is no obvious signal before the occurrence of Jichang landslide. The masses have a long runout distance of 1300 m. When it occurred, it demonstrated the characteristics of confidentiality and strong paroxysm. It caused great danger in large range. There can be a big attribution if such case can be studied further. It can provide the significant experience on dealing with this kind of masses failure and how to provide advice on early warning and remediation project on similar cases in southwestern mountain areas of China.
A large scale of mountain rock avalanche occurred at about 20:40 on July 23, 2019 in Jichang town, Shuicheng county, Guizhou Province. The rock mass moved down and scraped the original loose deposits and finally formed deposits of 191.2×104 m3. It destroyed parts of Pingdi Village, resulted in the death of 43 persons and missing of 9 persons. Based on site investigation, unmanned aerial vehicle(UAV)photography and other technologies, this paper provides a detailed description on the characteristics and a comprehensive analysis on the dynamic process and failure mechanism of the long runout landslide. And there is still a risk that the accumulation of the landslide can be translated into debris flow during rainfall. The results indicate that the special geometry of the source area, the weathered and shattered basalt mass and favorable combination of discontinuities are the internal cause factors for sliding. The rainfall infiltrating and its softening effect, and the road construction cut-slope are the external cause factors for the landslide. There is no obvious signal before the occurrence of Jichang landslide. The masses have a long runout distance of 1300 m. When it occurred, it demonstrated the characteristics of confidentiality and strong paroxysm. It caused great danger in large range. There can be a big attribution if such case can be studied further. It can provide the significant experience on dealing with this kind of masses failure and how to provide advice on early warning and remediation project on similar cases in southwestern mountain areas of China.
17
2019, 27(5): 1000-1009.
2019, 27(5): 1000-1009.
The topographic measurement of high-steep to upright slopes of complex terrain and the establishment of three-dimensional numerical models have always been puzzling geologists. In recent years, the unmanned aerial vehicle(UAV)has been widely used in geological surveys due to its small size, maneuverability, and the ability to acquire high-resolution images. This paper focuses on a new measuring and modeling method for high-steep/upright slopes with integration of UAV and many software. Firstly, on the basis of low-altitude UAV tilt photography, the Agisoft Photoscan 3D real scene modeling software and reverse engineering-based Geomagic Studio's powerful point cloud data processing function, we generate the topographic maps of high-steep/upright slope with complex terrain quickly, combine with the topographic mapping function of CASS. Subsequently, the high-steep/upright slope closed CAD surface models of complex terrain are reconstructed utilizing the CAD surface modeling function of Geomagic Studio. Then we take the advantages of the powerful geometric processing and meshing ability of Hypermesh to mesh the CAD surface models, before establishing a fine three-dimensional(3D)numerical model for high-steep/upright slopes of complex terrain. Finally, the 3D numerical model is converted into a file recognizable by FLAC3D for calculation and analysis. In order to illustrate this method in details, we take the Feitian Waterfall Scenic Spot in Shenxianju Scenic Spot in Zhejiang Province as an example. The results indicate that the use of UAV enables fast, efficient and accurate mapping and 3D modeling of high-steep/upright slopes in complex terrain. The method has the advantages of being simple and practical, fast and convenient, and strong practicality.
The topographic measurement of high-steep to upright slopes of complex terrain and the establishment of three-dimensional numerical models have always been puzzling geologists. In recent years, the unmanned aerial vehicle(UAV)has been widely used in geological surveys due to its small size, maneuverability, and the ability to acquire high-resolution images. This paper focuses on a new measuring and modeling method for high-steep/upright slopes with integration of UAV and many software. Firstly, on the basis of low-altitude UAV tilt photography, the Agisoft Photoscan 3D real scene modeling software and reverse engineering-based Geomagic Studio's powerful point cloud data processing function, we generate the topographic maps of high-steep/upright slope with complex terrain quickly, combine with the topographic mapping function of CASS. Subsequently, the high-steep/upright slope closed CAD surface models of complex terrain are reconstructed utilizing the CAD surface modeling function of Geomagic Studio. Then we take the advantages of the powerful geometric processing and meshing ability of Hypermesh to mesh the CAD surface models, before establishing a fine three-dimensional(3D)numerical model for high-steep/upright slopes of complex terrain. Finally, the 3D numerical model is converted into a file recognizable by FLAC3D for calculation and analysis. In order to illustrate this method in details, we take the Feitian Waterfall Scenic Spot in Shenxianju Scenic Spot in Zhejiang Province as an example. The results indicate that the use of UAV enables fast, efficient and accurate mapping and 3D modeling of high-steep/upright slopes in complex terrain. The method has the advantages of being simple and practical, fast and convenient, and strong practicality.
18
PROBABILITY OF COSEISMIC LANDSLIDES: A NEW GENERATION OF EARTHQUAKE-TRIGGERED LANDSLIDE HAZARD MODEL
2019, 27(5): 1122-1130.
2019, 27(5): 1122-1130.
The probability of the occurrence of coseismic landslides is basically blank. In this study, the Bayesian Probability Method and the Machine Model are used to carry out the real probability of coseismic landslides of China. The first generation of coseismic landslide hazard probability map of China is produced on the basis of nine earthquake cases. They include 1999 Chi-chi, Taiwan, 2005 Kashmir, 2008 Wenchuan, 2010 Yushu, 2013 Lushan, 2013 Minxian, 2014 Ludian, 2015 Nepal, and 2017 Jiuzhaigou earthquakes. Seven of the nine earthquakes occurred in China. The 2005 Kashmir and the 2015 Nepal quakes occurred in China's neighboring areas, which can better control the accuracy of the model. All these earthquake events have detailed and complete coseismic landslide inventories. They include 306 435 landslide polygons. Considering the real earthquake landslide occurrence area, the difference of landslide size, the ratio of landslide to non-slip sample ratio, a total of 5 117 000 samples are selected. A total of 13 factors are selected. They are absolute elevation, relative elevation, slope angle, slope aspect, slope curvature, slope position, topographic humidity index, land cover, vegetation coverage percentage, fault distance, stratum, average annual precipitation, and peak ground acceleration. The Bayesian probability method is combined with the machine learning model to establish a multi-factor impact model for the probability of earthquake-triggered landslide. Then the weights of each continuous factor and the weight of each class of the classification factor are obtained. The model is applied in China considering the peak ground acceleration as the triggering factor of landslides and considering the real probability of earthquake landslides in China under different peak ground accelerations(0.1~1 g, one result per 0.1 g, a total of 10 results). In addition, combined with Seismic Ground Motion Parameters Zonation Map of China, the corresponding true probability of earthquake-triggered landslides of China is generated.
The probability of the occurrence of coseismic landslides is basically blank. In this study, the Bayesian Probability Method and the Machine Model are used to carry out the real probability of coseismic landslides of China. The first generation of coseismic landslide hazard probability map of China is produced on the basis of nine earthquake cases. They include 1999 Chi-chi, Taiwan, 2005 Kashmir, 2008 Wenchuan, 2010 Yushu, 2013 Lushan, 2013 Minxian, 2014 Ludian, 2015 Nepal, and 2017 Jiuzhaigou earthquakes. Seven of the nine earthquakes occurred in China. The 2005 Kashmir and the 2015 Nepal quakes occurred in China's neighboring areas, which can better control the accuracy of the model. All these earthquake events have detailed and complete coseismic landslide inventories. They include 306 435 landslide polygons. Considering the real earthquake landslide occurrence area, the difference of landslide size, the ratio of landslide to non-slip sample ratio, a total of 5 117 000 samples are selected. A total of 13 factors are selected. They are absolute elevation, relative elevation, slope angle, slope aspect, slope curvature, slope position, topographic humidity index, land cover, vegetation coverage percentage, fault distance, stratum, average annual precipitation, and peak ground acceleration. The Bayesian probability method is combined with the machine learning model to establish a multi-factor impact model for the probability of earthquake-triggered landslide. Then the weights of each continuous factor and the weight of each class of the classification factor are obtained. The model is applied in China considering the peak ground acceleration as the triggering factor of landslides and considering the real probability of earthquake landslides in China under different peak ground accelerations(0.1~1 g, one result per 0.1 g, a total of 10 results). In addition, combined with Seismic Ground Motion Parameters Zonation Map of China, the corresponding true probability of earthquake-triggered landslides of China is generated.
19
2006, 14(S1): 449-455.
2006, 14(S1): 449-455.
In this paper, general characteristic of soft foundation pit is firstly introduced. The deformation and instability which often occur in soft foundation pit is analyzed and some conclusions are found, i.e., to control the deformation of these pits is the key point. Therefore, the application of composite soil-nail in soft foundation pit is suggested and some specific problems are discussed. Also, some good engineering cases are listed here to prove the effect of this approach. The case applications show that composite soil-nail is effective indeed for soft foundation pits if key steps are well controlled during the process of construction.
In this paper, general characteristic of soft foundation pit is firstly introduced. The deformation and instability which often occur in soft foundation pit is analyzed and some conclusions are found, i.e., to control the deformation of these pits is the key point. Therefore, the application of composite soil-nail in soft foundation pit is suggested and some specific problems are discussed. Also, some good engineering cases are listed here to prove the effect of this approach. The case applications show that composite soil-nail is effective indeed for soft foundation pits if key steps are well controlled during the process of construction.
20
2018, 26(1): 249-258.
2018, 26(1): 249-258.
The NSFC proposals and grants of engineering geology in 2017 are analyzed. The number of proposals has increased. The number of Young Scientists Fund and Excellent Young Scientists Fund proposals increased significantly in this year. The peer-review referees well handled the scale of peer-review on the proposals. The age distribution of the General Program applicants tends to be double-peak structure. The age distribution of the Young Scientists Fund applicant tends to be reasonable. The applicants of Key Program are older in age than average but tend to become younger than that in last year. The application of engineering geology has been funded in several different project types, showing a growing competitive trend.
The NSFC proposals and grants of engineering geology in 2017 are analyzed. The number of proposals has increased. The number of Young Scientists Fund and Excellent Young Scientists Fund proposals increased significantly in this year. The peer-review referees well handled the scale of peer-review on the proposals. The age distribution of the General Program applicants tends to be double-peak structure. The age distribution of the Young Scientists Fund applicant tends to be reasonable. The applicants of Key Program are older in age than average but tend to become younger than that in last year. The application of engineering geology has been funded in several different project types, showing a growing competitive trend.
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