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Editor Work2002 Vol. 10, No. 4
Previous Issue
2002, 10(4): 339-342.
Abstract
On the basis of extensive examination of information, the article systemically summarizes all classifications of landslides in the world. In complete consideration of all affecting factors, the advantages of various classifications of landslides are clearly understood and the relationship between the factors is clarified . A system for classifing landslides is set up after scientific reduction, selection, and supplementation, and hence a sound foundation for costruction of a geological modelling system for monitoring and predicting landslide is formed. All these will be beneficial for further study of development of landslides. Generally, the classification methods of landslides can be summarized as follows: (1)To classify landslides according to apparent features of landslide bodies, including structure, occurence and size of a landslide body and depending on the stability of a landslide.(2)To classify landslides according to inducements, which include natural inducements and human-activity inducements, which can cause the occurrence of a landslide as an environmental factor. (3) To classify landslides according to the development of a landslide, including its deformation, movement, and failure, which and reflect the dynamic characteristics of a landslide.
On the basis of extensive examination of information, the article systemically summarizes all classifications of landslides in the world. In complete consideration of all affecting factors, the advantages of various classifications of landslides are clearly understood and the relationship between the factors is clarified . A system for classifing landslides is set up after scientific reduction, selection, and supplementation, and hence a sound foundation for costruction of a geological modelling system for monitoring and predicting landslide is formed. All these will be beneficial for further study of development of landslides. Generally, the classification methods of landslides can be summarized as follows: (1)To classify landslides according to apparent features of landslide bodies, including structure, occurence and size of a landslide body and depending on the stability of a landslide.(2)To classify landslides according to inducements, which include natural inducements and human-activity inducements, which can cause the occurrence of a landslide as an environmental factor. (3) To classify landslides according to the development of a landslide, including its deformation, movement, and failure, which and reflect the dynamic characteristics of a landslide.
2002, 10(4): 343-348.
It is evident that the rainfalls has a remarkable effect on slope stability, but it is generally analyzed by static pore water pressure theory based on saturated soil. Actually, in most cases, the soil, especially the coarse soil and rocks, is discovered to be unsaturated or has a process from unsaturated to saturated state during rainfall. Therefore, a new slope stability analysis approach is necessary based on unsaturated soil theory. In this paper, the effect of unsaturated soils suction on slope stability is discussed from basic Mohr-Coulombs shear strength model. Based on that we suggest a modified GLE method considering suction for unsaturated slope. This method was used to an open pit mine slope and it revealed some basic laws of suction on slope stability. The slope safety factor from this new GLE method is higher than that from traditional one, but it has a bigger decrease in the process from saturated to unsaturated state and the final safety factor when the seepage being over is smaller than that from general pore water pressure theory.
It is evident that the rainfalls has a remarkable effect on slope stability, but it is generally analyzed by static pore water pressure theory based on saturated soil. Actually, in most cases, the soil, especially the coarse soil and rocks, is discovered to be unsaturated or has a process from unsaturated to saturated state during rainfall. Therefore, a new slope stability analysis approach is necessary based on unsaturated soil theory. In this paper, the effect of unsaturated soils suction on slope stability is discussed from basic Mohr-Coulombs shear strength model. Based on that we suggest a modified GLE method considering suction for unsaturated slope. This method was used to an open pit mine slope and it revealed some basic laws of suction on slope stability. The slope safety factor from this new GLE method is higher than that from traditional one, but it has a bigger decrease in the process from saturated to unsaturated state and the final safety factor when the seepage being over is smaller than that from general pore water pressure theory.
2002, 10(4): 349-355.
Combining the developing history, the definition and related research topics of Environmental Geotechnology are introduced, the international advances and developing trends of the discipline are outlined, and finally, the current and future tasks of environmental geotechnology in China are suggested in this paper.
Combining the developing history, the definition and related research topics of Environmental Geotechnology are introduced, the international advances and developing trends of the discipline are outlined, and finally, the current and future tasks of environmental geotechnology in China are suggested in this paper.
2002, 10(4): 356-366.
Loess has various particular properties. One of them is its collapsibility when inundated with water. Collapse deformation occurs on a large scale, at a great speed. A rapid degradation of mechanical characteristics takes place when loess is wetted at constant stress.After a brief review of various criteria which were utilized for identifying collapse soils and are based on laboratory tests, a new simple methods were proposed to evaluate in situ loess collapsibility with help of dynamic penetrometer tests and static loading tests. The method consists in carrying out penetrometer tests with a portable dynamic penetrometer of variable energy in natural and saturated conditions as a first step, a compressibility test (static loading test) is then performed after the cone penetrometer tests.The paper presents the procedure of in situ penetrometer testing and static loading testing. With the data measured in Central Loess Plateau in China, a detailed analysis of correlation between loess cone resistance q dnat in natural conditions, q dsat in saturated conditions, the index of collapsibility s measured in laboratory and compressibility curve parameters (penetrometer limit pressure p pf , penetrometer creep pressure p pl and penetrometer modulus E pn ) was taken. The results permit to state that the method proposed is suitable to characterize in situ loess collapsibility.
Loess has various particular properties. One of them is its collapsibility when inundated with water. Collapse deformation occurs on a large scale, at a great speed. A rapid degradation of mechanical characteristics takes place when loess is wetted at constant stress.After a brief review of various criteria which were utilized for identifying collapse soils and are based on laboratory tests, a new simple methods were proposed to evaluate in situ loess collapsibility with help of dynamic penetrometer tests and static loading tests. The method consists in carrying out penetrometer tests with a portable dynamic penetrometer of variable energy in natural and saturated conditions as a first step, a compressibility test (static loading test) is then performed after the cone penetrometer tests.The paper presents the procedure of in situ penetrometer testing and static loading testing. With the data measured in Central Loess Plateau in China, a detailed analysis of correlation between loess cone resistance q dnat in natural conditions, q dsat in saturated conditions, the index of collapsibility s measured in laboratory and compressibility curve parameters (penetrometer limit pressure p pf , penetrometer creep pressure p pl and penetrometer modulus E pn ) was taken. The results permit to state that the method proposed is suitable to characterize in situ loess collapsibility.
2002, 10(4): 367-377.
Neogene hard clay is widely distributed in the Cenozoic basins of east China, and is the main subject of regional studies of special sedimentary materials for its special properties. The middle line of the North-South Diversion Water Project lies across the west edge of Nanyang basin and the north China basin, excavating in various kinds of Neogene hard clay. Based on laboratory experiment and measurements, this paper presents the engineering geological properties of Neogene hard clay from the Nanyang basin, as well as Fangcheng Baofeng and Handan Yongnian regions, including the composition and physicochemical properties, physical properties shrink-swell characteristics, strength and other properties, and summarizes their formation mechanisms and variation laws. Meanwhile, the environmental effect under different humidity and lateral pressures is summarized, which is helpful to understand the deformation mechanism of Neogene hard clay under the condition of excavation and engineering operation.
Neogene hard clay is widely distributed in the Cenozoic basins of east China, and is the main subject of regional studies of special sedimentary materials for its special properties. The middle line of the North-South Diversion Water Project lies across the west edge of Nanyang basin and the north China basin, excavating in various kinds of Neogene hard clay. Based on laboratory experiment and measurements, this paper presents the engineering geological properties of Neogene hard clay from the Nanyang basin, as well as Fangcheng Baofeng and Handan Yongnian regions, including the composition and physicochemical properties, physical properties shrink-swell characteristics, strength and other properties, and summarizes their formation mechanisms and variation laws. Meanwhile, the environmental effect under different humidity and lateral pressures is summarized, which is helpful to understand the deformation mechanism of Neogene hard clay under the condition of excavation and engineering operation.
2002, 10(4): 378-384.
A large volume of analysis of grain size, aggregate components, pore size and distribution before and after consolidation, and micro-structure and pore solution composition and exchangeable cations of soft clay in Shanghai was conducted. The possible effect of the pore size variation with consolidation and artificial injection is discussed. And the effect of microscopic characteristics of soft clay on consolidation and deformation of soil mass is depicted from physico-chemical theory. At last, in this paper a new ideas of controll on consolidation and deformation of soft clay is presented.
A large volume of analysis of grain size, aggregate components, pore size and distribution before and after consolidation, and micro-structure and pore solution composition and exchangeable cations of soft clay in Shanghai was conducted. The possible effect of the pore size variation with consolidation and artificial injection is discussed. And the effect of microscopic characteristics of soft clay on consolidation and deformation of soil mass is depicted from physico-chemical theory. At last, in this paper a new ideas of controll on consolidation and deformation of soft clay is presented.
2002, 10(4): 385-389.
Analysis of main and secondary consolidation behaviors of soft foundation is an important subject of theoretical value and practical significance. Large numbers of consolidation tests of marine soft soil in Tianjin were performed. From the viewpoint of microstructure, the inflexion of consolidation curve is explained in combination with potential energy curve . The variation regularity of secondary-consolidation coefficient is studied. Meanwhile, the relation of secondary-consolidation coefficient with time, consolidation pressure, and compression index are established.
Analysis of main and secondary consolidation behaviors of soft foundation is an important subject of theoretical value and practical significance. Large numbers of consolidation tests of marine soft soil in Tianjin were performed. From the viewpoint of microstructure, the inflexion of consolidation curve is explained in combination with potential energy curve . The variation regularity of secondary-consolidation coefficient is studied. Meanwhile, the relation of secondary-consolidation coefficient with time, consolidation pressure, and compression index are established.
2002, 10(4): 390-394.
Engineering analysis of recent marine soft soil settlement is based on a traditional one-dimensional drainage consolidation theory of Terzaghi.K. Because of specific engineering-geological properties of the marine soft soil, i. e. high porosity ratio, high water content, high compressibility, and low permeability, the result of calculation is not consistent with actual situation. In this paper, on basis of analysis of SEM data and pressure mercury test, the authors analyze the essential factors of affecting the soft soil consolidation. At last, by means of one-dimensional compression test, the authors compare the theoretical curve of consolidation with the test curve of compression, analyze the causes for deviation of two curves, set forth the mechanism for consolidation of marine soft soil, and put forward a new concept of bound water consolidation.
Engineering analysis of recent marine soft soil settlement is based on a traditional one-dimensional drainage consolidation theory of Terzaghi.K. Because of specific engineering-geological properties of the marine soft soil, i. e. high porosity ratio, high water content, high compressibility, and low permeability, the result of calculation is not consistent with actual situation. In this paper, on basis of analysis of SEM data and pressure mercury test, the authors analyze the essential factors of affecting the soft soil consolidation. At last, by means of one-dimensional compression test, the authors compare the theoretical curve of consolidation with the test curve of compression, analyze the causes for deviation of two curves, set forth the mechanism for consolidation of marine soft soil, and put forward a new concept of bound water consolidation.
DISCUSSION ON SOME PROBLEMS OF APPLICATION OF TAMPING ENERGY TO FOUNDATION WITH LARGE FILL THICKNESS
2002, 10(4): 395-399.
A lot of engineering practice indicates when the dynamic compaction is used to reinforce founation of fill, the selection of tamping energy is not only related to the thickness of fill, but also to the conditions of soil and groundwater table, etc. In this paper, a discussion is made on the use of tamping energy to reinforce the foundation with large fill thickness in southern China. If the substratum of the fill is either hard or soft, and if the filling material is coarse aggregate and fine aggregate that is cohesive soil with high water content, respectively. The selected standard of tamping energy is established in different conditions. From the data of field monitoring, an evaluation is made of the effectiveness of foundation reinforcement by adequately determining the tamping energy, so that the better consolidation effects could be achieved.
A lot of engineering practice indicates when the dynamic compaction is used to reinforce founation of fill, the selection of tamping energy is not only related to the thickness of fill, but also to the conditions of soil and groundwater table, etc. In this paper, a discussion is made on the use of tamping energy to reinforce the foundation with large fill thickness in southern China. If the substratum of the fill is either hard or soft, and if the filling material is coarse aggregate and fine aggregate that is cohesive soil with high water content, respectively. The selected standard of tamping energy is established in different conditions. From the data of field monitoring, an evaluation is made of the effectiveness of foundation reinforcement by adequately determining the tamping energy, so that the better consolidation effects could be achieved.
2002, 10(4): 400-403.
Based on the experiences in the ongoing mining engineering practice in the high-stress fractured ore body, the paper first presents a key support technique(OTEST) according to the primary-secondary coordinated interaction zones. The technique not only emphasizes support time and support strength for fractured rock in roadways under high stress, but it most importantly different from the conventional to first evade then to resist, and to take secondary support guiding principle. Further , OTEST has also its detail and clear definition of the support type, support structure and operation procedure. The successful application experience of this technique to typical sites at the Xiaoguanzhuang Iron Mine shows that the technique OTEST is correct and useful.
Based on the experiences in the ongoing mining engineering practice in the high-stress fractured ore body, the paper first presents a key support technique(OTEST) according to the primary-secondary coordinated interaction zones. The technique not only emphasizes support time and support strength for fractured rock in roadways under high stress, but it most importantly different from the conventional to first evade then to resist, and to take secondary support guiding principle. Further , OTEST has also its detail and clear definition of the support type, support structure and operation procedure. The successful application experience of this technique to typical sites at the Xiaoguanzhuang Iron Mine shows that the technique OTEST is correct and useful.
2002, 10(4): 404-407.
The purpose of this paper is to analyze the variation of pore pressure and flow amount of gas in the course of mining by a great deal of site tests. The result shows that the coalbed containing gas is a complex system. The key factor causing the system to change is the stress in coal bed. The pressure of gas increases exponentially with increasing stress in coal bed; and the gas seepage is controlled by gradient of gas pressure.
The purpose of this paper is to analyze the variation of pore pressure and flow amount of gas in the course of mining by a great deal of site tests. The result shows that the coalbed containing gas is a complex system. The key factor causing the system to change is the stress in coal bed. The pressure of gas increases exponentially with increasing stress in coal bed; and the gas seepage is controlled by gradient of gas pressure.
2002, 10(4): 408-414.
After Chongqing became a municipality directly under Central Goverment, its area widened from 23,000 km 2 to 82,000 km 2 and its previous resources and environmental data could not meet the needs of government policy-making. It is urgent to systematically analyze geological environmental of Chongqing and evaluate its regional stability. Basing on the available materials and data, the regional stability of Chongqing municipality is evaluated in this paper by using analytical hierarchy process method and Fuzzy mathematics method.
After Chongqing became a municipality directly under Central Goverment, its area widened from 23,000 km 2 to 82,000 km 2 and its previous resources and environmental data could not meet the needs of government policy-making. It is urgent to systematically analyze geological environmental of Chongqing and evaluate its regional stability. Basing on the available materials and data, the regional stability of Chongqing municipality is evaluated in this paper by using analytical hierarchy process method and Fuzzy mathematics method.
2002, 10(4): 415-420.
Summing up the experiences in engineering-geological investigation of the Yellow River embankment, the paper studies and demonstrates systematically the investigation methods for solving three major problems of historic dyke breach.
Summing up the experiences in engineering-geological investigation of the Yellow River embankment, the paper studies and demonstrates systematically the investigation methods for solving three major problems of historic dyke breach.
2002, 10(4): 421-427.
The integration of GIS and corresponding models plays more and more important role in analysis of landslide hazard. To select proper model and its elements is a key issue for landslide hazard analysis. After an integrated discussion of GIS-aided model for analysis current landslide hazard, the characteristics of each model and their elements and their limitations are studied in detail. Then some important conclusions are made.
The integration of GIS and corresponding models plays more and more important role in analysis of landslide hazard. To select proper model and its elements is a key issue for landslide hazard analysis. After an integrated discussion of GIS-aided model for analysis current landslide hazard, the characteristics of each model and their elements and their limitations are studied in detail. Then some important conclusions are made.
2002, 10(4): 428-433.
The social economic attribute of geo hazards made the study on them to be different from the traditional engineering geological study. Analysis of the geo hazards from their social economic attribute will yields more social economic benefits. The hazard risk and the vulnerability of the objects are basic elements of the regional geo hazard evaluation. One of the most important risk analyses is the GIS aided geo hazard study. Based on the authors studies in the last years, a risk analysis system for regional geo hazards (RiskAnly) has been developed on the basis of software MAPGIS. The paper introduces the train of system design, structures and workflow of the RiskAnly. As a case study, the paper also deals with the risk zonation of a landslide hazard region of China.
The social economic attribute of geo hazards made the study on them to be different from the traditional engineering geological study. Analysis of the geo hazards from their social economic attribute will yields more social economic benefits. The hazard risk and the vulnerability of the objects are basic elements of the regional geo hazard evaluation. One of the most important risk analyses is the GIS aided geo hazard study. Based on the authors studies in the last years, a risk analysis system for regional geo hazards (RiskAnly) has been developed on the basis of software MAPGIS. The paper introduces the train of system design, structures and workflow of the RiskAnly. As a case study, the paper also deals with the risk zonation of a landslide hazard region of China.
2002, 10(4): 434-437.
One-dimensional general model of land subsidence due to pumping is deduced and a semi-analytical method is used to solve this deviatoric differential equation. The model takes vertical effective stress as a basic variatable and considers the variation of permeability coefficient and compression coefficient with the vertical effective stress. The actual case shows that the result from the proposed model is much better than Terzaghis theory and very close to the measured result.
One-dimensional general model of land subsidence due to pumping is deduced and a semi-analytical method is used to solve this deviatoric differential equation. The model takes vertical effective stress as a basic variatable and considers the variation of permeability coefficient and compression coefficient with the vertical effective stress. The actual case shows that the result from the proposed model is much better than Terzaghis theory and very close to the measured result.
2002, 10(4): 438-439.
Geotechnical problems from three aspects are discussed in this paper: environmental protection, topography, and ground foundation. Some control measures are proposed to relieve them.
Geotechnical problems from three aspects are discussed in this paper: environmental protection, topography, and ground foundation. Some control measures are proposed to relieve them.
2002, 10(4): 440-442.
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