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1
2002, 10(S1): 655-660.
Abstract
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The paper demonstrates that multiple compound can use different pole materials, different construction methods and make full use of bearing capacity of ground soil in order to eliminate ground liquefaction as well as meet requirements of bearing capacity of ground. Through cost of comparing, prove that multiple compound is a handling method of ground which whose construction method is easy, cost is comparatively economical and deserves being spread. The technology of composite foundation using CFG stake is adopted in improving the bearing strength for soft subsoil. And in this paper,the principle of multiple compound, the characteristics of CFG stake&two ash pile reinforcing soft subsoil and practice data are analyzed. According to the inspection of the engineering effect, the disposition method of composite foundation using CFG stake&two ash pile can achieve the design requirements.This method is economic in cutting down the engineering cost and has better economic and society benefit.
The paper demonstrates that multiple compound can use different pole materials, different construction methods and make full use of bearing capacity of ground soil in order to eliminate ground liquefaction as well as meet requirements of bearing capacity of ground. Through cost of comparing, prove that multiple compound is a handling method of ground which whose construction method is easy, cost is comparatively economical and deserves being spread. The technology of composite foundation using CFG stake is adopted in improving the bearing strength for soft subsoil. And in this paper,the principle of multiple compound, the characteristics of CFG stake&two ash pile reinforcing soft subsoil and practice data are analyzed. According to the inspection of the engineering effect, the disposition method of composite foundation using CFG stake&two ash pile can achieve the design requirements.This method is economic in cutting down the engineering cost and has better economic and society benefit.
2
2002, 10(S1): 210-216.
The process of taphrogenic differential settlement can be regarded as limited system. The authors in this paper,based on dynamic characteristics of taphrogenic differential settlement in geological skilled works' school, Xi'an city, by means of two-dimension limited system theory, processes monitor data and forecasts life circle or life span of settlement.The paper analyzes the affect of taphrogenic differential settlement 45 years later, which come from forecast, on subway tunnel, simulates it which limited system theory incomputer, and make a conclusion of that taphrogenic differential settlement will break subway tunnel 45 years later. Therefore, we must adopt effective measure to limit exploitation of deep pressing groundwater, and strengthen the construction technology and materials of subway tunnel. Thus we can ensure subway move smoothly tomorrow. The paper furnishes the reference material for building subway and it's running.
The process of taphrogenic differential settlement can be regarded as limited system. The authors in this paper,based on dynamic characteristics of taphrogenic differential settlement in geological skilled works' school, Xi'an city, by means of two-dimension limited system theory, processes monitor data and forecasts life circle or life span of settlement.The paper analyzes the affect of taphrogenic differential settlement 45 years later, which come from forecast, on subway tunnel, simulates it which limited system theory incomputer, and make a conclusion of that taphrogenic differential settlement will break subway tunnel 45 years later. Therefore, we must adopt effective measure to limit exploitation of deep pressing groundwater, and strengthen the construction technology and materials of subway tunnel. Thus we can ensure subway move smoothly tomorrow. The paper furnishes the reference material for building subway and it's running.
3
ANALYSIS OF FACTORS AFFECTING DISTRIBUTION OF LANDSLIDE THRUST FORCE FOR DOUBLE-ROW ANTI-SLIDE PILES
2011, 19(3): 359-363.
This paper takes the basic form of double-row cantilever beam anti-slide piles without joist as the model.Based on structural analysis theory,it presents the equations for calculating the transferring push force and the distribution between the double-row piles..It further uses the Hongshibao landslide as a case study for analyzing the double-row pile static row spacing,the section size of back and front piles,and the soil elasticity modulus between piles.It examines their influences to the thrust force distribution.Conclusions from the examination are obtained as follows: (1)When either the rigidity of the back pile increases or the rigidity of the front piles decreases,the extrusion interacting force between the soil and the two-row piles decreases,A2/A1 decreases along with it.Otherwise A2/A1 increases.(2)When the row distance b increases,A1 decreases,A2 decreases gradually when b=3 to 10m; A2 increases when b=10 to 21m. (3)When increases the elasticity coefficient between piles,A2 increases.(4)Along with the increases of the section high of the front piles,both A1 and A2 increases gradually; along with the increases of the section high of the back piles,both A1and A2 decreases gradually.
This paper takes the basic form of double-row cantilever beam anti-slide piles without joist as the model.Based on structural analysis theory,it presents the equations for calculating the transferring push force and the distribution between the double-row piles..It further uses the Hongshibao landslide as a case study for analyzing the double-row pile static row spacing,the section size of back and front piles,and the soil elasticity modulus between piles.It examines their influences to the thrust force distribution.Conclusions from the examination are obtained as follows: (1)When either the rigidity of the back pile increases or the rigidity of the front piles decreases,the extrusion interacting force between the soil and the two-row piles decreases,A2/A1 decreases along with it.Otherwise A2/A1 increases.(2)When the row distance b increases,A1 decreases,A2 decreases gradually when b=3 to 10m; A2 increases when b=10 to 21m. (3)When increases the elasticity coefficient between piles,A2 increases.(4)Along with the increases of the section high of the front piles,both A1 and A2 increases gradually; along with the increases of the section high of the back piles,both A1and A2 decreases gradually.
4
2011, 19(2): 284-288.
The purpose of landslide monitoring is to obtain the characteristics and evolutionary process of landslides.For some important sites,monitoring in deep ground is the most direct and effective means to determine whether or not potential landslide exists,in this paper,five boreholes for underground monitoring are set on two profiles of a slope behind a hydropower plant.Slide area,slope activity,sliding direction,sliding surface and types of the landslide are discussed and analyzed.The monitoring results reveal that it is a retrogressive landslide with obvious activity.The displacement velocity of the landslide is large and it has accelerated in the rainy seasons.Sliding surface in the slope front has been locally penetrated.It alsohas creep deformation in the upslope.
The purpose of landslide monitoring is to obtain the characteristics and evolutionary process of landslides.For some important sites,monitoring in deep ground is the most direct and effective means to determine whether or not potential landslide exists,in this paper,five boreholes for underground monitoring are set on two profiles of a slope behind a hydropower plant.Slide area,slope activity,sliding direction,sliding surface and types of the landslide are discussed and analyzed.The monitoring results reveal that it is a retrogressive landslide with obvious activity.The displacement velocity of the landslide is large and it has accelerated in the rainy seasons.Sliding surface in the slope front has been locally penetrated.It alsohas creep deformation in the upslope.
5
2008, 16(4): 450-458.
Ya'an to Lugu expressway is a part of the Beijing to Kunming expressway. The Lama stream is spanned by the Lama Stream Bridge along the Ya'an to Lugu expressway. To investigate engineering geological conditions at the bridge, a geological survey and field reconnaissance were conducted prior to the bridge construction. It was found that the geo-environmental conditions near and around the planned bridge site were very complicated. The so-called Xigeda strata have low strength and collapsing characteristics, which can be strongly affected by water. Under the action of water and geological structure, landslide can easily occur in slopes comprising the Xigeda strata. Base on the ground investigations at the Wenwu slope on the Lama stream along the Ya'an to Lugu expressway, this paper presents the engineering geologic and hydrogeological conditions of the landslides comprising the Xigeda strata. The paper gives results on the properties of Xigeda strata, the geological structure and groundwater. It analyzes the causes and contributing factors, finds the optimal slope gradients, the optimal slope shapes, the angle and height of slopes sensitive to landslide. It grades the dangerous degrees according to angle of slope. It provides a basis for further evaluation of slope stability. Finally, it presents some reasonable reinforcements, fill and compression and drainage measures adaptable to the geological conditions.
Ya'an to Lugu expressway is a part of the Beijing to Kunming expressway. The Lama stream is spanned by the Lama Stream Bridge along the Ya'an to Lugu expressway. To investigate engineering geological conditions at the bridge, a geological survey and field reconnaissance were conducted prior to the bridge construction. It was found that the geo-environmental conditions near and around the planned bridge site were very complicated. The so-called Xigeda strata have low strength and collapsing characteristics, which can be strongly affected by water. Under the action of water and geological structure, landslide can easily occur in slopes comprising the Xigeda strata. Base on the ground investigations at the Wenwu slope on the Lama stream along the Ya'an to Lugu expressway, this paper presents the engineering geologic and hydrogeological conditions of the landslides comprising the Xigeda strata. The paper gives results on the properties of Xigeda strata, the geological structure and groundwater. It analyzes the causes and contributing factors, finds the optimal slope gradients, the optimal slope shapes, the angle and height of slopes sensitive to landslide. It grades the dangerous degrees according to angle of slope. It provides a basis for further evaluation of slope stability. Finally, it presents some reasonable reinforcements, fill and compression and drainage measures adaptable to the geological conditions.
6
2011, 19(1): 43-51.
Landslide risk management has become one of the most important methods for landslide mitigation in the world. However, it starts relatively late and it is still in the initial stage in China (Hong Kong is an exceptional). The concept and techniques of landslide risk management widely used internationally have not been well implemented in the project of landslide investigation in China. This paper takes the project of landslide investigation at Baota district in Yanan city deployed by the land resources survey as an example. It analyzes the problem when doing the project about geohazards investigation, and the differences among the and the idea of risk management according to the guidelines for landslide susceptibility hazard and risk zoning for land use planning issued by JTC-1[1] and some new references. The landslide investigation implemented in China is medium scale and the investigation accuracy includes high, medium and low. A technical route and working thought about loess landslide investigation and mapping based on GIS, DEM, RS and ground survey is proposed. The study covers the four aspects including the landslide investigation and risk mapping at the scale of 1∶50000 and 1∶10000, the landslide investigation and risk mapping in villages, the important infrastructures and the representative landslides.The paper summarizes the loess landslide investigation and risk mapping methods at Baota district in Yanan city.
Landslide risk management has become one of the most important methods for landslide mitigation in the world. However, it starts relatively late and it is still in the initial stage in China (Hong Kong is an exceptional). The concept and techniques of landslide risk management widely used internationally have not been well implemented in the project of landslide investigation in China. This paper takes the project of landslide investigation at Baota district in Yanan city deployed by the land resources survey as an example. It analyzes the problem when doing the project about geohazards investigation, and the differences among the and the idea of risk management according to the guidelines for landslide susceptibility hazard and risk zoning for land use planning issued by JTC-1[1] and some new references. The landslide investigation implemented in China is medium scale and the investigation accuracy includes high, medium and low. A technical route and working thought about loess landslide investigation and mapping based on GIS, DEM, RS and ground survey is proposed. The study covers the four aspects including the landslide investigation and risk mapping at the scale of 1∶50000 and 1∶10000, the landslide investigation and risk mapping in villages, the important infrastructures and the representative landslides.The paper summarizes the loess landslide investigation and risk mapping methods at Baota district in Yanan city.
7
2020, 28(2): 255-281.
Soil-rock mixture (S-RM) is one of the widely distributed and unique geological materials in China and around the world. It is composed of loose rocks and soil, and has become a key carrier for mountain geological hazards. The complex structure of S-RM is the key to evaluate its special physical and mechanical properties. In this paper, the strength, deformation and permeability characteristics of S-RM and its structural control mechanisms are thoroughly studied, based on the multi-scale macro and micro tests, physical and mechanical field tests, numerical simulation, in order to interpret the control mechanisms of crucial structure factors. The factors include rock proportion, soil-rock shape, matrix composition and internal soil-rock granularity composition. Furthermore, the soil-rock control laws of the randomness of the S-RM strength and deformation characteristics are determined. In addition, much more accurate acquisition methods of strength parameters in different structural states are also proposed. The nonlinear seepage calculation model and its optimal design method of anti-seepage deformation are obtained, through the study on the nonlinear permeability characteristics of S-RM with different stone contents. In summary, this study provides a certain theoretical support for the comprehensive establishment of new generation of S-MR landslide early-warning system, based on the real soil-rock structures and nonlinear constitutive relation.
Soil-rock mixture (S-RM) is one of the widely distributed and unique geological materials in China and around the world. It is composed of loose rocks and soil, and has become a key carrier for mountain geological hazards. The complex structure of S-RM is the key to evaluate its special physical and mechanical properties. In this paper, the strength, deformation and permeability characteristics of S-RM and its structural control mechanisms are thoroughly studied, based on the multi-scale macro and micro tests, physical and mechanical field tests, numerical simulation, in order to interpret the control mechanisms of crucial structure factors. The factors include rock proportion, soil-rock shape, matrix composition and internal soil-rock granularity composition. Furthermore, the soil-rock control laws of the randomness of the S-RM strength and deformation characteristics are determined. In addition, much more accurate acquisition methods of strength parameters in different structural states are also proposed. The nonlinear seepage calculation model and its optimal design method of anti-seepage deformation are obtained, through the study on the nonlinear permeability characteristics of S-RM with different stone contents. In summary, this study provides a certain theoretical support for the comprehensive establishment of new generation of S-MR landslide early-warning system, based on the real soil-rock structures and nonlinear constitutive relation.
8
2012, 20(6): 909-915.
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.
9
2008, 16(S1): 677-680.
n this paper, based on the laboratory test, analyzed the relationship between the shear strength and plastic index of remolded clay in Shanghai. And also analyzed the relationship between the shear strength and the depth of soil layer .The results indicate that the shear strength and plastic index of the remolded clay has little linear correlation. And with the depth of soil increasing, the angle of internal friction decreases gradually.
n this paper, based on the laboratory test, analyzed the relationship between the shear strength and plastic index of remolded clay in Shanghai. And also analyzed the relationship between the shear strength and the depth of soil layer .The results indicate that the shear strength and plastic index of the remolded clay has little linear correlation. And with the depth of soil increasing, the angle of internal friction decreases gradually.
10
2008, 16(5): 694-698.
The landslide thrust is the important evidence for the designed thrust of anti - slide p ile. It is often cal2 culated with the residual thrustmethod. On the basis of residual thrustmethod, a new method to find the designed thrust of anti - slide p ile is p roposed for an accurate and reasonable result. On the condition of limit equilibrium state and safety requirement, the residual thrust is calculated and reasonable p ile position is determined to make it locate the anti - slide segment of landslide. Residual thrust of landslide lies behind the p ile is adjusted to ensure not only that adjustment quantity can meet safety requirement, but also it can be modify on the basis of the designed thrust of anti - slide p ile. All of this consideration is realized with p rocedure. The method is verified with exam2 p les. It also p rovides reference function for reasonable value of the designed thrust of anti - slide p iles in the future.
The landslide thrust is the important evidence for the designed thrust of anti - slide p ile. It is often cal2 culated with the residual thrustmethod. On the basis of residual thrustmethod, a new method to find the designed thrust of anti - slide p ile is p roposed for an accurate and reasonable result. On the condition of limit equilibrium state and safety requirement, the residual thrust is calculated and reasonable p ile position is determined to make it locate the anti - slide segment of landslide. Residual thrust of landslide lies behind the p ile is adjusted to ensure not only that adjustment quantity can meet safety requirement, but also it can be modify on the basis of the designed thrust of anti - slide p ile. All of this consideration is realized with p rocedure. The method is verified with exam2 p les. It also p rovides reference function for reasonable value of the designed thrust of anti - slide p iles in the future.
11
2007, 15(S1): 391-396.
The reason why Dayan Pagoda inclined was given in the point of writers' view. Excessive gross loading intensity, incompatible foundation and soil improvement, the differences in their thickness and quality led to the early inclination. The influence of water environment caused its development in the late period of it.
The reason why Dayan Pagoda inclined was given in the point of writers' view. Excessive gross loading intensity, incompatible foundation and soil improvement, the differences in their thickness and quality led to the early inclination. The influence of water environment caused its development in the late period of it.
12
2017, 25(2): 257-276.
From October 13 to 21, 2016, the 10th National Engineering Geological Conference is successfully held in Chengdu, Sichuan Province. In the opening ceremony, the author delivered a keynote presentation entitled "Engineering Geology: Review and Prospect of Past Ten Years". The author was the Chairman of the Eighth and Ninth Engineering Geology Committee. So this paper is his work review over past ten years. The author sums up with three phrases for the development of Engineering Geology in China over past ten years. They are a) Founding super engineering projects, b) Protecting people's well-being, c) Promoting the development of academic disciplines. Over the past ten years, Engineering Geology in China closely integrated with the national strategic demands and scientific and technical problems in engineering, provided the technical supports for the national super project construction, greatly reduced the death toll caused by the geological disasters through the theoretical innovation and the technological development, and made a large number of representative theoretical and technological results. The author also expresses his great expectation that China's Engineering Geology will reach the world's top level.
From October 13 to 21, 2016, the 10th National Engineering Geological Conference is successfully held in Chengdu, Sichuan Province. In the opening ceremony, the author delivered a keynote presentation entitled "Engineering Geology: Review and Prospect of Past Ten Years". The author was the Chairman of the Eighth and Ninth Engineering Geology Committee. So this paper is his work review over past ten years. The author sums up with three phrases for the development of Engineering Geology in China over past ten years. They are a) Founding super engineering projects, b) Protecting people's well-being, c) Promoting the development of academic disciplines. Over the past ten years, Engineering Geology in China closely integrated with the national strategic demands and scientific and technical problems in engineering, provided the technical supports for the national super project construction, greatly reduced the death toll caused by the geological disasters through the theoretical innovation and the technological development, and made a large number of representative theoretical and technological results. The author also expresses his great expectation that China's Engineering Geology will reach the world's top level.
13
2012, 20(6): 903-908.
Water resistance is one of the most important factors which affect the speed of the fording landslide when it enters water at a high speed. The experiment system is designed. It includes movement apparatus, sensor apparatus, speed control apparatus and transmission apparatus. Six blocks with different areas of water attaining surface are selected to carry out experiments. Each block moves in water at five different speeds. They are 0.5ms-1、0.8ms-1、1.0ms-1、1.5ms-1 and 1.8ms-1. The correlation between Incremental pressure head and moving speed is analyzed by experiment method. The pressure head model is established to the resistance of water attaining surface when blokes move in water. As for the curved-surface sliding model of fording landslide, the forces of sliding masses both in water and above water are calculated. The kinetics equation and kinematics equation are used to calculate landslide speeds. At last, the speed model of fording landslide is put forward by slice method when landslide moves along a curved slip surface. The paper takes the Dayantang landslide that was located on the north side of Qing River and occurred on June 15, 2007 as an example. The speeds of landslide with water resistance acting on water attaining surface are compared with those of landslide without water resistance. The influences on the landslide speed from the water resistance are quantitatively analyzed.
Water resistance is one of the most important factors which affect the speed of the fording landslide when it enters water at a high speed. The experiment system is designed. It includes movement apparatus, sensor apparatus, speed control apparatus and transmission apparatus. Six blocks with different areas of water attaining surface are selected to carry out experiments. Each block moves in water at five different speeds. They are 0.5ms-1、0.8ms-1、1.0ms-1、1.5ms-1 and 1.8ms-1. The correlation between Incremental pressure head and moving speed is analyzed by experiment method. The pressure head model is established to the resistance of water attaining surface when blokes move in water. As for the curved-surface sliding model of fording landslide, the forces of sliding masses both in water and above water are calculated. The kinetics equation and kinematics equation are used to calculate landslide speeds. At last, the speed model of fording landslide is put forward by slice method when landslide moves along a curved slip surface. The paper takes the Dayantang landslide that was located on the north side of Qing River and occurred on June 15, 2007 as an example. The speeds of landslide with water resistance acting on water attaining surface are compared with those of landslide without water resistance. The influences on the landslide speed from the water resistance are quantitatively analyzed.
14
2010, 18(S1): 220-228.
Geological conditions of tunnel are always highly changing and complex,as to ensure the safety and high efficiency in the construction.Its very necessary and importantly to do the predictions of bad natural geological bodies in the construction period.TSP as one of Amberg Measuring Technique corporation s advanced product.Its a geological forecast system specifically design for the long tunnel geological prediction.Compared with other prediction method,from the data collection,processing to interpretation and evaluation are all highly intelligent.In this paper,TSP principle,features,technology development,TSPs problems,etc.were systematically explained.Finally,gave a brief summary on Tunnel Seismic Prediction.Wish to promote TSP application in tunnel construction.
Geological conditions of tunnel are always highly changing and complex,as to ensure the safety and high efficiency in the construction.Its very necessary and importantly to do the predictions of bad natural geological bodies in the construction period.TSP as one of Amberg Measuring Technique corporation s advanced product.Its a geological forecast system specifically design for the long tunnel geological prediction.Compared with other prediction method,from the data collection,processing to interpretation and evaluation are all highly intelligent.In this paper,TSP principle,features,technology development,TSPs problems,etc.were systematically explained.Finally,gave a brief summary on Tunnel Seismic Prediction.Wish to promote TSP application in tunnel construction.
15
2013, 21(1): 25-44.
The latest research results indicate that the 2008 Wenchuan Earthquake(MS 8.0)triggered more than 197000 landslides. Base on Geographic Information Systems(GIS) and remote sensing technologies, three(nearly) complete landslide catalogs are constructed firstly. The three catalogs are corresponds to respective landslide polygons, landside centroid points, and landslide top points respectively. These catalogs indicate that there were 197481 landslides triggered by the Wenchuan earthquake throughout an area of about 110000km2.These landslides are delineated as respective individual solid polygons, landslide central dots, and landslide top dots using visual interpretation of high resolution aerial photographs and satellite images taken pre-and post-earthquake, verified by selected field checking. These landslides cover a total area of about 1160km2.An area covers about 44031km2 is selected as study area. There are 196007 landslides. They have a total area of 1150.6km2 occurred in the study area. This landslide catalog is the most detailed and complete landslide inventory related with the 2008 Wenchuan earthquake. It is also the largest landslide inventory record related to a single earthquake event. Subsequently, spatial distribution statistical analysis of landslides triggered by the 2008 Wenchuan earthquake are carried out in the study area. Base on the inventories of landslide polygons and landslide centroid points, two density maps, named landslide area density map and landslide point density map were constructed, respectively. Both the two landslide density maps show that landslide activities primarily concentrate along the Yingxiu-Beichuan co-seismic surface fault-rupture, and most of the landslides occurred on the hanging wall. The highest landslide density areas appear in the northwest direction areas, on the hanging wall, of a section of the Yingxiu-Beichuan fault(from the Yingxiu Town to the Beichuan County).Those high intensive landslide areas correspond to high deformation areas during the earthquake. So, it can be concluded that the earthquake triggered landslides is very strongly affected by co-seismic deformation. Furthermore, correlations of landslide occurrence with seismic parameters, geologic and topographic conditions are analyzed using the three landslide catalogs. Statistical analysis of these landslides spatial distribution using (a) landslide area percentage(LAP),defined as the percentage of the area affected by the landslides,(b) landslide centroid number density(LCND),defined as the number of landslide centroid per square kilometer, and (c) landslide top number density(LTND),defined as the number of landslide top point per square kilometer, is carried out to determine how the occurrence of landslides correlates with elevation, slope angle, slope aspect, slope position, slope curvature, lithology, distance from epicenter, seismic intensity, distance from the Yingxiu-Beichuan surface fault-rupture, peak ground acceleration(PGA).It is observed that the LAP,LCND, and LTND values have positive correlations with slope angle, PGA, and seismic intensity, and have negative correlations with distance from epicenter, and distance from the Yingxiu-Beichuan surface fault-rupture. More slope curvature close to zero, more difficult to landslide occurrence. The highest values of one LAP and two LND appear at range from 1200m to 3000m in elevation. The landslides have preferred orientations, dominated by the eastern, southeastern, and southern directions. The sandstone, siltstone(Z) and granitic rocks have more concentrated landslides. No apparent correlations were found between LAP,two LND values and slope position. Statistical results also show that differences between LCND and LTND is very small for earthquake and geologic parameters, rather more difference relate with topographic parameters. Some qualitative comparisons between the results in this paper and others published papers are carried out finally. There would be obvious differences of statistical results related to correlations of landsides and elevation, lithology, distance from the epicenter, distance from the Yingxiu-Beichuan fault from the present results and in other publications. In addition to those parameters, the statistical result from other factors including slope angle and slope aspect show similar tendency. So, it can be concluded that a complete, detailed and accurate landslide catalog is an essential part for seismic landslide hazard analyses and spatial distribution statistical analyses. Otherwise, parts of results obtained from analyzing uncompleted landslide distribution data would be controversial. It is rather necessary and important to construct complete landslide catalogs for seismic landslide spatial distribution statistical quantitative analyses, hazard assessment, and landscape evolution controlled by earthquake triggered landslides in earthquake struck area, et al.
The latest research results indicate that the 2008 Wenchuan Earthquake(MS 8.0)triggered more than 197000 landslides. Base on Geographic Information Systems(GIS) and remote sensing technologies, three(nearly) complete landslide catalogs are constructed firstly. The three catalogs are corresponds to respective landslide polygons, landside centroid points, and landslide top points respectively. These catalogs indicate that there were 197481 landslides triggered by the Wenchuan earthquake throughout an area of about 110000km2.These landslides are delineated as respective individual solid polygons, landslide central dots, and landslide top dots using visual interpretation of high resolution aerial photographs and satellite images taken pre-and post-earthquake, verified by selected field checking. These landslides cover a total area of about 1160km2.An area covers about 44031km2 is selected as study area. There are 196007 landslides. They have a total area of 1150.6km2 occurred in the study area. This landslide catalog is the most detailed and complete landslide inventory related with the 2008 Wenchuan earthquake. It is also the largest landslide inventory record related to a single earthquake event. Subsequently, spatial distribution statistical analysis of landslides triggered by the 2008 Wenchuan earthquake are carried out in the study area. Base on the inventories of landslide polygons and landslide centroid points, two density maps, named landslide area density map and landslide point density map were constructed, respectively. Both the two landslide density maps show that landslide activities primarily concentrate along the Yingxiu-Beichuan co-seismic surface fault-rupture, and most of the landslides occurred on the hanging wall. The highest landslide density areas appear in the northwest direction areas, on the hanging wall, of a section of the Yingxiu-Beichuan fault(from the Yingxiu Town to the Beichuan County).Those high intensive landslide areas correspond to high deformation areas during the earthquake. So, it can be concluded that the earthquake triggered landslides is very strongly affected by co-seismic deformation. Furthermore, correlations of landslide occurrence with seismic parameters, geologic and topographic conditions are analyzed using the three landslide catalogs. Statistical analysis of these landslides spatial distribution using (a) landslide area percentage(LAP),defined as the percentage of the area affected by the landslides,(b) landslide centroid number density(LCND),defined as the number of landslide centroid per square kilometer, and (c) landslide top number density(LTND),defined as the number of landslide top point per square kilometer, is carried out to determine how the occurrence of landslides correlates with elevation, slope angle, slope aspect, slope position, slope curvature, lithology, distance from epicenter, seismic intensity, distance from the Yingxiu-Beichuan surface fault-rupture, peak ground acceleration(PGA).It is observed that the LAP,LCND, and LTND values have positive correlations with slope angle, PGA, and seismic intensity, and have negative correlations with distance from epicenter, and distance from the Yingxiu-Beichuan surface fault-rupture. More slope curvature close to zero, more difficult to landslide occurrence. The highest values of one LAP and two LND appear at range from 1200m to 3000m in elevation. The landslides have preferred orientations, dominated by the eastern, southeastern, and southern directions. The sandstone, siltstone(Z) and granitic rocks have more concentrated landslides. No apparent correlations were found between LAP,two LND values and slope position. Statistical results also show that differences between LCND and LTND is very small for earthquake and geologic parameters, rather more difference relate with topographic parameters. Some qualitative comparisons between the results in this paper and others published papers are carried out finally. There would be obvious differences of statistical results related to correlations of landsides and elevation, lithology, distance from the epicenter, distance from the Yingxiu-Beichuan fault from the present results and in other publications. In addition to those parameters, the statistical result from other factors including slope angle and slope aspect show similar tendency. So, it can be concluded that a complete, detailed and accurate landslide catalog is an essential part for seismic landslide hazard analyses and spatial distribution statistical analyses. Otherwise, parts of results obtained from analyzing uncompleted landslide distribution data would be controversial. It is rather necessary and important to construct complete landslide catalogs for seismic landslide spatial distribution statistical quantitative analyses, hazard assessment, and landscape evolution controlled by earthquake triggered landslides in earthquake struck area, et al.
16
2019, 27(1): 123-133.
In view of the difficulty in implementing active reinforcement for the high-level rockfall disaster occurred in the high-steep slope zone of the "5·12" Wenchuan earthquake area in 2008, the pile-plate retaining wall is a passive protection measure used in the proposed interception site, and its applicable terrain slope is 25°~35°. In order to study the dynamic response of such a pile-plate structure under rockfall impact load, numerical simulation is carried out by coupling finite element and infinite element. Combined with the classical elastoplastic theory, the characteristic parameters such as impact force, penetration depth and structural energy dissipation effect of the pile-plate retaining wall during loading and unloading rebound process under different impact conditions are systematically analyzed, and the impact resistance of the structure is clarified. The results show that the "infinite element" boundary can effectively reduce the error caused by the reflection of the stress wave at the artificial truncation boundary. In the case of impact speeds of 10 m·s-1, 15 m·s-1 and 20 m·s-1, 25 m·s-1, the calculated impact forces are 1.9MN, 2.5MN, 3.1MN, 3.7MN, respectively. The results are consistent with the Kawahara model, but larger than the Labiouse model and the Hertz elastic solution. According to the concrete damage theory, the classification of damage level is proposed and the degree of structural damage is effectively quantified. When the impact speed is greater than 20 m·s-1, the pile and plate concrete tensile damage is seriously damaged, and the structure has the risk of completely losing the bearing capacity. The calculation methods and results in this paper can provide practical guidance for the related structural design.
In view of the difficulty in implementing active reinforcement for the high-level rockfall disaster occurred in the high-steep slope zone of the "5·12" Wenchuan earthquake area in 2008, the pile-plate retaining wall is a passive protection measure used in the proposed interception site, and its applicable terrain slope is 25°~35°. In order to study the dynamic response of such a pile-plate structure under rockfall impact load, numerical simulation is carried out by coupling finite element and infinite element. Combined with the classical elastoplastic theory, the characteristic parameters such as impact force, penetration depth and structural energy dissipation effect of the pile-plate retaining wall during loading and unloading rebound process under different impact conditions are systematically analyzed, and the impact resistance of the structure is clarified. The results show that the "infinite element" boundary can effectively reduce the error caused by the reflection of the stress wave at the artificial truncation boundary. In the case of impact speeds of 10 m·s-1, 15 m·s-1 and 20 m·s-1, 25 m·s-1, the calculated impact forces are 1.9MN, 2.5MN, 3.1MN, 3.7MN, respectively. The results are consistent with the Kawahara model, but larger than the Labiouse model and the Hertz elastic solution. According to the concrete damage theory, the classification of damage level is proposed and the degree of structural damage is effectively quantified. When the impact speed is greater than 20 m·s-1, the pile and plate concrete tensile damage is seriously damaged, and the structure has the risk of completely losing the bearing capacity. The calculation methods and results in this paper can provide practical guidance for the related structural design.
17
2009, 17(4): 538-544.
According to the monitored data of Saleshan landslide, three nonlinear prediction models (i.e., exponential model, Verhulst model and grey GM(1,1) model) for the landslide deformation is developed in this paper. The models are based on the studying of combined model with optimum weight and Gauss-Newton method. Then the combined model with optimum weight of the landslide is built. The parameters in each individual model and the combined model are optimized using Gauss-Newton method. By analyzing and comparing, the paper can conclude that the prediction accuracy of the combined model are higher than that of an individual model. The precision for each model after optimizing parameters using Gauss-Newton method is obviously higher than that of the models before using the optimizing parameters. The combined model with the optimizing parameters in all models has the highest precision. So, it is an effective and feasible method for improving landslide prediction to use the combined model with optimum weight and Gauss-Newton method.
According to the monitored data of Saleshan landslide, three nonlinear prediction models (i.e., exponential model, Verhulst model and grey GM(1,1) model) for the landslide deformation is developed in this paper. The models are based on the studying of combined model with optimum weight and Gauss-Newton method. Then the combined model with optimum weight of the landslide is built. The parameters in each individual model and the combined model are optimized using Gauss-Newton method. By analyzing and comparing, the paper can conclude that the prediction accuracy of the combined model are higher than that of an individual model. The precision for each model after optimizing parameters using Gauss-Newton method is obviously higher than that of the models before using the optimizing parameters. The combined model with the optimizing parameters in all models has the highest precision. So, it is an effective and feasible method for improving landslide prediction to use the combined model with optimum weight and Gauss-Newton method.
18
2003, 11(2): 220-222.
Engineering geological study is aimed at maximal adoption to and protection of the environment by engineering construction and running: holism of nature-human being. So its theoretical kernel-interaction between engineering and the environment, and its objects include natural engineering geological conditions and the environment geological action and environment effects of engineering, i.e.. artificial geological phenomena, especially, possible artificial geological disasters. All these studies should be carried out from region to construction site to region again, from depth to shallow part to depth again(view of control by region and depth, view of expansion of enviromental effects), from history to present condition to near and distant future(view of natural and artificial history); Whereas the study on environmental effects of engineering-from one to all(without omission)to most important one (to stress the main points):holism of time-space-state. Microscopically, rock mass-soil mass structure mechanical study, rock mass-soil mass hydraulical study and rock-soil-water-gas physico-chemical study should be developed simultaneously with emphasis on structure mechanicsl study. Macroscopically, studies from view point of geoscience, environmtnal science, engineering science and system science should be developed simultaneously with emphasis on study from view point of geoscience: holism of macro-microscopic studies. On the basis of all these studies geological, mechanical, mathematical and management models are estabilished step by step. These models are solved and realized with development and application of exploration, testing, physical and digital, simulation, prediction, monitoring, management techniques:holism of ends-means. Based on above-stated, a system of engineering geology, the status of engineering geology as branch of learning, setting up of research and education organizations, and training of specialists-engineering geologists are suggested in this paper.
Engineering geological study is aimed at maximal adoption to and protection of the environment by engineering construction and running: holism of nature-human being. So its theoretical kernel-interaction between engineering and the environment, and its objects include natural engineering geological conditions and the environment geological action and environment effects of engineering, i.e.. artificial geological phenomena, especially, possible artificial geological disasters. All these studies should be carried out from region to construction site to region again, from depth to shallow part to depth again(view of control by region and depth, view of expansion of enviromental effects), from history to present condition to near and distant future(view of natural and artificial history); Whereas the study on environmental effects of engineering-from one to all(without omission)to most important one (to stress the main points):holism of time-space-state. Microscopically, rock mass-soil mass structure mechanical study, rock mass-soil mass hydraulical study and rock-soil-water-gas physico-chemical study should be developed simultaneously with emphasis on structure mechanicsl study. Macroscopically, studies from view point of geoscience, environmtnal science, engineering science and system science should be developed simultaneously with emphasis on study from view point of geoscience: holism of macro-microscopic studies. On the basis of all these studies geological, mechanical, mathematical and management models are estabilished step by step. These models are solved and realized with development and application of exploration, testing, physical and digital, simulation, prediction, monitoring, management techniques:holism of ends-means. Based on above-stated, a system of engineering geology, the status of engineering geology as branch of learning, setting up of research and education organizations, and training of specialists-engineering geologists are suggested in this paper.
19
2019, 27(5): 1188-1198.
In the current classification of rock and soil, there is a fragmentation problem to cause lots of fuzzy zones among various rock or soil types. The general classification of rock and soil should be based on the basic material compositions, ie, soild, liquid and gas. Generally, the combination scheme of special components, grain diameter, porosity and degree of saturation can be adopted. In this paper, special components include orgnic matter and special minerals including layered minerals represented by montmorillonite, soluble salts and carbonate minerals. The general classification index has to be applicable to various kinds of rock and soil. But some parameters only suitable for a special rock or soil can be used as the secondary classification index. Grain sizes and special components are adopted to classify particles of rock & soil, porosity to measure the absolute compactness among particles and degree of saturation to measure moisture content. A rock or soil stratum is defined as the one with the same geological age, the same genetic type and the same special components, grain sizes, compactness and degree of saturation. The standard sequence of rock & soil strata is defined as the complete sequence of rock and soil strata for a special geological age and a genetic type in a region. It is an important foundation of large database of rock and soil strata to establish the standard sequence of rock & soil strata for all the geological ages and genetic types in a region, nation or the whole world.
In the current classification of rock and soil, there is a fragmentation problem to cause lots of fuzzy zones among various rock or soil types. The general classification of rock and soil should be based on the basic material compositions, ie, soild, liquid and gas. Generally, the combination scheme of special components, grain diameter, porosity and degree of saturation can be adopted. In this paper, special components include orgnic matter and special minerals including layered minerals represented by montmorillonite, soluble salts and carbonate minerals. The general classification index has to be applicable to various kinds of rock and soil. But some parameters only suitable for a special rock or soil can be used as the secondary classification index. Grain sizes and special components are adopted to classify particles of rock & soil, porosity to measure the absolute compactness among particles and degree of saturation to measure moisture content. A rock or soil stratum is defined as the one with the same geological age, the same genetic type and the same special components, grain sizes, compactness and degree of saturation. The standard sequence of rock & soil strata is defined as the complete sequence of rock and soil strata for a special geological age and a genetic type in a region. It is an important foundation of large database of rock and soil strata to establish the standard sequence of rock & soil strata for all the geological ages and genetic types in a region, nation or the whole world.
20
2012, 20(5): 663-673.
Upon drying, the evaporation of soil water results in volumetric shrinkage and desiccation cracks on expansive soils. The presence of crack can significantly weaken the engineering properties of soil, and cause various problems in geological, geotechnical, hydraulic, environmental engineering fields. With the increasing frequency of severe drought climate, the engineering problems that induced by desiccation cracking can be more and more, worse and worse. The study of desiccation cracking is therefore very significant for revealing the intrinsic mechanisms behind this common natural phenomenon, and plays an important role in engineering practice in clayey soil areas and especially in expansive soil areas. Generally, the initiation and propagation of desiccation cracks show evident dynamic characteristics and significantly depend on soil water evaporation rate, stress state and shrinkage property. The cracks initiate at constant evaporation rate stage. Soil suction and tensile strength are the two key mechanical parameters that control the cracking behavior. Cracking is likely to occur if the tensile stress which is induced by soil suction reaches the tensile strength of soil. Intrinsically, cracking is the result of pore shrinkage. It is believed that the mechanical effect and shrinkage potential are the two necessary factors for crack initiation. It is found that the desiccation cracking behaviour is affected by many factors including soil materials, mechanical properties, structures, test conditions, and test methods. Quantitative characterization of crack patterns is required for desiccation cracking investigation, and plays very important role in understanding the cracking mechanism and constructing the relevant model. Image processing is a powerful, efficient and high-accurate tool for quantitative description crack patterns. In the next stage, more attention should be paid to the dynamic characteristics of cracking, and more work should be done on water-soil interaction, mechanical mechanism, shrinkage mechanism, large scale field test and 3D quantification technique that related to soil desiccation cracking. It is also important to study desiccation cracking behaviour on the basis of soil materials, mechanics and structures, to integrate macro-observation with micro-analysis and to construct perfect theory for characterizing desiccation cracking.
Upon drying, the evaporation of soil water results in volumetric shrinkage and desiccation cracks on expansive soils. The presence of crack can significantly weaken the engineering properties of soil, and cause various problems in geological, geotechnical, hydraulic, environmental engineering fields. With the increasing frequency of severe drought climate, the engineering problems that induced by desiccation cracking can be more and more, worse and worse. The study of desiccation cracking is therefore very significant for revealing the intrinsic mechanisms behind this common natural phenomenon, and plays an important role in engineering practice in clayey soil areas and especially in expansive soil areas. Generally, the initiation and propagation of desiccation cracks show evident dynamic characteristics and significantly depend on soil water evaporation rate, stress state and shrinkage property. The cracks initiate at constant evaporation rate stage. Soil suction and tensile strength are the two key mechanical parameters that control the cracking behavior. Cracking is likely to occur if the tensile stress which is induced by soil suction reaches the tensile strength of soil. Intrinsically, cracking is the result of pore shrinkage. It is believed that the mechanical effect and shrinkage potential are the two necessary factors for crack initiation. It is found that the desiccation cracking behaviour is affected by many factors including soil materials, mechanical properties, structures, test conditions, and test methods. Quantitative characterization of crack patterns is required for desiccation cracking investigation, and plays very important role in understanding the cracking mechanism and constructing the relevant model. Image processing is a powerful, efficient and high-accurate tool for quantitative description crack patterns. In the next stage, more attention should be paid to the dynamic characteristics of cracking, and more work should be done on water-soil interaction, mechanical mechanism, shrinkage mechanism, large scale field test and 3D quantification technique that related to soil desiccation cracking. It is also important to study desiccation cracking behaviour on the basis of soil materials, mechanics and structures, to integrate macro-observation with micro-analysis and to construct perfect theory for characterizing desiccation cracking.
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