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Editor Work2001 Vol. 9, No. 4
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2001, 9(4): 339-344.
Abstract
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Presented in this paper are the results of experimental study and analysis of liquefaction characteristics of clayey sand .The laboratory tests on soil samples after prepared with the same dry density and different clay mineralogical composition and different content of clay particles were so as to determine the main parameters which affect the liquefaction behaviour of clayey sand .The tests were performed run on DSD-200 type dynamic triaxial device. X-ray diffraction analysis was also performed. By comparison of the obtained data, the following conclutions are drawn out: (1) the liquefaction-resistant characteristic of clayey sand varies with different clay mineralogical composition; (2)the relation between the dynamic shear strength and the clay particles is not monotonous, but is parabolic and a regression equation for the parabola is given presented by the authors;(3)when the clay particle content is between 8.5～9.5%, the clayey sand is weakest liquefaction-resistant.
Presented in this paper are the results of experimental study and analysis of liquefaction characteristics of clayey sand .The laboratory tests on soil samples after prepared with the same dry density and different clay mineralogical composition and different content of clay particles were so as to determine the main parameters which affect the liquefaction behaviour of clayey sand .The tests were performed run on DSD-200 type dynamic triaxial device. X-ray diffraction analysis was also performed. By comparison of the obtained data, the following conclutions are drawn out: (1) the liquefaction-resistant characteristic of clayey sand varies with different clay mineralogical composition; (2)the relation between the dynamic shear strength and the clay particles is not monotonous, but is parabolic and a regression equation for the parabola is given presented by the authors;(3)when the clay particle content is between 8.5～9.5%, the clayey sand is weakest liquefaction-resistant.
2001, 9(4): 345-348.
The shear rheologic behaviors of soil in slip zone of a large-scale landslide are studied in this paper. The samples are prepared in accordence with the gravity compaction principles and by Chen Zonglis the loading method. The rheologic behaviors of soil in slip zone are described by the Burgers visco-elastic Model. From the test results, the long-term strength parameters are obtained, and its significance in study of the stability of landslide is also discussed.
The shear rheologic behaviors of soil in slip zone of a large-scale landslide are studied in this paper. The samples are prepared in accordence with the gravity compaction principles and by Chen Zonglis the loading method. The rheologic behaviors of soil in slip zone are described by the Burgers visco-elastic Model. From the test results, the long-term strength parameters are obtained, and its significance in study of the stability of landslide is also discussed.
2001, 9(4): 349-352.
This article gives a new discussion and a new evaluation method about the three parameters of the Barton equation, according to tests of the shear strength in some laboratories. When the shear strength (, ) of a discontinuity in a jointed rock mass is obtained, the problem how to stimulate three parameters (, JRC , JCS) of the Barton equation should be solved theoretically. But it is impossible to apply the partial derivative equation for solving the problem because of the specialty of the Barton equation. On the basis of discussion of the Barton equation, this article applies the least square method and compiles some programs to solve the problem, and a very good result is gotten.
This article gives a new discussion and a new evaluation method about the three parameters of the Barton equation, according to tests of the shear strength in some laboratories. When the shear strength (, ) of a discontinuity in a jointed rock mass is obtained, the problem how to stimulate three parameters (, JRC , JCS) of the Barton equation should be solved theoretically. But it is impossible to apply the partial derivative equation for solving the problem because of the specialty of the Barton equation. On the basis of discussion of the Barton equation, this article applies the least square method and compiles some programs to solve the problem, and a very good result is gotten.
2001, 9(4): 353-356.
The characteristics of rockmass block are the main indexes, which are usually represented by RQD. But RQD has some disadvantages. The probability distribution of basic rockmass block, block percentage, RQD t, and rockmass block index (RBI), as the important supplements to defining the rockmass block, are also used to describe the characteristics of rockmass block, which are representative of the rockmass integrality more allsidedly and effectively and enrich the assessment system of rockmass quality. Based on the investigation and statistics of the rockmass block at dam foundation of Xiluodu Water Power Plant Project in the downstream of Jinshajiang River , the rockmass block characteristics, such as the probability distribution of basic rockmass block, block percentage, RQD t and rockmass block index (RBI), were deeply studied.
The characteristics of rockmass block are the main indexes, which are usually represented by RQD. But RQD has some disadvantages. The probability distribution of basic rockmass block, block percentage, RQD t, and rockmass block index (RBI), as the important supplements to defining the rockmass block, are also used to describe the characteristics of rockmass block, which are representative of the rockmass integrality more allsidedly and effectively and enrich the assessment system of rockmass quality. Based on the investigation and statistics of the rockmass block at dam foundation of Xiluodu Water Power Plant Project in the downstream of Jinshajiang River , the rockmass block characteristics, such as the probability distribution of basic rockmass block, block percentage, RQD t and rockmass block index (RBI), were deeply studied.
2001, 9(4): 357-361.
By using a Rock Failure Process Analysis code (RFPA 2D), slip failure process and associated seismicity in rock masses are numerically studied.The slipping rock mass seems to be of brittle and heterogeneous materials.The simulation result reproduced the whole process from deformation to failure leading to instability inducing seismicity in slipping rock masses and associated acoustic emissions.It shows that shear plane is the main feature of the slip failure mode.The shear plane as it initiated on the one termination of the crack, extends to the center and then to another termination.Finally, a macro scopic shear fault plane is observed.
By using a Rock Failure Process Analysis code (RFPA 2D), slip failure process and associated seismicity in rock masses are numerically studied.The slipping rock mass seems to be of brittle and heterogeneous materials.The simulation result reproduced the whole process from deformation to failure leading to instability inducing seismicity in slipping rock masses and associated acoustic emissions.It shows that shear plane is the main feature of the slip failure mode.The shear plane as it initiated on the one termination of the crack, extends to the center and then to another termination.Finally, a macro scopic shear fault plane is observed.
2001, 9(4): 362-367.
Saturated soil is a kind of loosed medium filled with water in the pores. Such soil will be deformed nonlinearly when subjected to the dynamic load, hence its constitutive law has its specific features. A dynamic triaxial soil testing system MTS-810 with high precision and high sensitivity is used to conduct a series of modelling tests for assessing the dynamic consolidation effects on soil foundation for the first time. The test conditions are in full accord with the actual soil conditions. The test data including dynamic stress and displacement as well as pore pressure can be collected with the time interval of millisecond. By combining with different test conditions, a lot of test data with high precision were obtained. On such a basis, the variation of all variables with time in process of dynamically consolidation as well as their interralation are comprehensively studied. The result provides a scientific base for dynamic consolidation research. Using the modelling test results, the dynamically constitutive law for dynamic consolidated saturated soil is derived. It is obtained based on the precise dynamic consolidation modelling test. Therefore it can reflect the actual soil state of dynamic consolidation and relevant problems can be solved with the improved model.
Saturated soil is a kind of loosed medium filled with water in the pores. Such soil will be deformed nonlinearly when subjected to the dynamic load, hence its constitutive law has its specific features. A dynamic triaxial soil testing system MTS-810 with high precision and high sensitivity is used to conduct a series of modelling tests for assessing the dynamic consolidation effects on soil foundation for the first time. The test conditions are in full accord with the actual soil conditions. The test data including dynamic stress and displacement as well as pore pressure can be collected with the time interval of millisecond. By combining with different test conditions, a lot of test data with high precision were obtained. On such a basis, the variation of all variables with time in process of dynamically consolidation as well as their interralation are comprehensively studied. The result provides a scientific base for dynamic consolidation research. Using the modelling test results, the dynamically constitutive law for dynamic consolidated saturated soil is derived. It is obtained based on the precise dynamic consolidation modelling test. Therefore it can reflect the actual soil state of dynamic consolidation and relevant problems can be solved with the improved model.
2001, 9(4): 368-372.
Dewatering is a new technology in soft soil foundation treatment. By dewatering, hydrostatic pressure decreases and effective normal stress correspondingly increases. Then the soft soil is consolidated and subded . In this paper, by analyzing pore-water pressure monitoring data of the dewatering and preloading test on a project in Pudong , the mechanism and pore water effect of dewatering foundation reinforcement are briefly discussed.
Dewatering is a new technology in soft soil foundation treatment. By dewatering, hydrostatic pressure decreases and effective normal stress correspondingly increases. Then the soft soil is consolidated and subded . In this paper, by analyzing pore-water pressure monitoring data of the dewatering and preloading test on a project in Pudong , the mechanism and pore water effect of dewatering foundation reinforcement are briefly discussed.
2001, 9(4): 373-376.
In this paper, a quantitative analysis of the spatial combination regularities of different kinds of structural planes from mechanics is made and the related formulas are derived, then a method to forecast and predict elements of the faults occurence influencing the areal stability or rock mass stability, the orientation and amplitude of the derived tectonic stress field.
In this paper, a quantitative analysis of the spatial combination regularities of different kinds of structural planes from mechanics is made and the related formulas are derived, then a method to forecast and predict elements of the faults occurence influencing the areal stability or rock mass stability, the orientation and amplitude of the derived tectonic stress field.
2001, 9(4): 377-380.
The Houhe Reservoir is a water project compensating for housing immigrants from the Xiaolangdi Hydro-junction project in Yuanqu county. Fault structure and weathering unload, caused leakage at the dam basement and shoulders of both banks. A GJMZ method is used to calculate and prefer the orientation of inclined boreholes for grouting and drainage after analyzing the data. The result provides a scientific basis for design department.
The Houhe Reservoir is a water project compensating for housing immigrants from the Xiaolangdi Hydro-junction project in Yuanqu county. Fault structure and weathering unload, caused leakage at the dam basement and shoulders of both banks. A GJMZ method is used to calculate and prefer the orientation of inclined boreholes for grouting and drainage after analyzing the data. The result provides a scientific basis for design department.
2001, 9(4): 381-384.
It always is very difficult to get an analytical equation of limit state for reliability analysis of underground rock space. In this paper provided a way to fit analytical equation of limit state by response surface method and numerical simulation experiments is suggested, and on this basis the reliability of system is calcculated.This method is used in reliability analysis of surrounding rockmass stability of underground tailing bin.
It always is very difficult to get an analytical equation of limit state for reliability analysis of underground rock space. In this paper provided a way to fit analytical equation of limit state by response surface method and numerical simulation experiments is suggested, and on this basis the reliability of system is calcculated.This method is used in reliability analysis of surrounding rockmass stability of underground tailing bin.
2001, 9(4): 385-388.
By statistical analysis of earthquake response result of real layered soil and comparison with observation result of acceleration of strong earthquakes, this paper discusses the amplification effect of bedrock peak acceleration caused by different site conditions and its characteristics. The analysis result can provide a reference for compiling zoning map of an area from ground motion parameters, evaluation of site effect in seismic safety analysis, and estimation of site ground motion according to its bedrock motion.
By statistical analysis of earthquake response result of real layered soil and comparison with observation result of acceleration of strong earthquakes, this paper discusses the amplification effect of bedrock peak acceleration caused by different site conditions and its characteristics. The analysis result can provide a reference for compiling zoning map of an area from ground motion parameters, evaluation of site effect in seismic safety analysis, and estimation of site ground motion according to its bedrock motion.
2001, 9(4): 389-392.
The issue of constructing buildings in swelling soil area is always a hot topic in geotechnical engineering circle, and is a hard subject in water conservancy projects. For this reason, systematic test and study of the properties of swelling soil is conducted in this paper in combination with the practical engineering work of Shuicheng Reservoir. The Shuicheng Reservoir is located in a swelling soil area, its dam is a stone-filling dam with a core wall, 59.2m height in maximum. Systematic physio-mechanical properties test and analysis, especially analysis of relationship between expansion rate, dry density, water content, and overlying pressure, are carried out. It is concluded that the expansion rate of swelling soil in this area is relatedd not only with mineral components in itself, but also dominated by natural dry density, water content, and the overlying pressure. The regularities of their relations are also got.
The issue of constructing buildings in swelling soil area is always a hot topic in geotechnical engineering circle, and is a hard subject in water conservancy projects. For this reason, systematic test and study of the properties of swelling soil is conducted in this paper in combination with the practical engineering work of Shuicheng Reservoir. The Shuicheng Reservoir is located in a swelling soil area, its dam is a stone-filling dam with a core wall, 59.2m height in maximum. Systematic physio-mechanical properties test and analysis, especially analysis of relationship between expansion rate, dry density, water content, and overlying pressure, are carried out. It is concluded that the expansion rate of swelling soil in this area is relatedd not only with mineral components in itself, but also dominated by natural dry density, water content, and the overlying pressure. The regularities of their relations are also got.
2001, 9(4): 393-398.
To counter the general behaviors of soft rock at great depth, a new support technique of soft rock tunnel at great depth is suggested in this paper. Firstly change the recently used sequence of bolting and shotcreting and then mix h the standard concrete with a certain amount of steel fiber to improve the mechanical behavior of standard concrete so that the shotcrete can meet the needs of large deformation of soft rock. The numerical modelling is employed to compare the support schemes and a reasonable scheme is proposed. The support scheme is practiced successfully at the transport tunnel on the level -575m of the Coal Mine No.10 of Hebi Coal Mining Administration.
To counter the general behaviors of soft rock at great depth, a new support technique of soft rock tunnel at great depth is suggested in this paper. Firstly change the recently used sequence of bolting and shotcreting and then mix h the standard concrete with a certain amount of steel fiber to improve the mechanical behavior of standard concrete so that the shotcrete can meet the needs of large deformation of soft rock. The numerical modelling is employed to compare the support schemes and a reasonable scheme is proposed. The support scheme is practiced successfully at the transport tunnel on the level -575m of the Coal Mine No.10 of Hebi Coal Mining Administration.
2001, 9(4): 399-403.
Investigation and analysis of engineering-geological conditions for 5 airports in North China, chemical analysis, petrographical facies analysis, electron microscope and X-Ray analysis of the properties and constituents of the concrete aggregate and product of its erosion, soil and water were carried out. An arrest reaction of alkaline concrete aggregate with coal cinder powder was tested. The preliminary vesut shows that preferred engineering-geological conditions and isolation layer design are the effective way to controlling the concrete aggregate erosion.
Investigation and analysis of engineering-geological conditions for 5 airports in North China, chemical analysis, petrographical facies analysis, electron microscope and X-Ray analysis of the properties and constituents of the concrete aggregate and product of its erosion, soil and water were carried out. An arrest reaction of alkaline concrete aggregate with coal cinder powder was tested. The preliminary vesut shows that preferred engineering-geological conditions and isolation layer design are the effective way to controlling the concrete aggregate erosion.
2001, 9(4): 404-407.
Study on the theory of critical superstatic pore water pressure, permitted to suggest a method for calculating depth of liquefaction. It was used to calculate the depth of liquefaction in the coastal area of Tangshan, which was caused by Tangshan earthquake in 1976, and compares the calculation result with measured data.
Study on the theory of critical superstatic pore water pressure, permitted to suggest a method for calculating depth of liquefaction. It was used to calculate the depth of liquefaction in the coastal area of Tangshan, which was caused by Tangshan earthquake in 1976, and compares the calculation result with measured data.
2001, 9(4): 408-413.
Some new theory and methods for development of slope rock block stability analysis system are presented in this paper. Being different from others, in the theory a cutting method is used to set up a block model by which the problem of complicated geometry shapes, such as hexahedron blocks can be solved. Theoretically, this method can be generally used for evaluating the stability of wedge-blocks with arbitrary geometric shapes. A software package based on above theory has been developed in the environment of Windows 3.x and Windows 95. As a typical example, the new theory and software have been applied to stability analysis of wedge slope at shiplock high slopes in Three-Gorges Project, the far hydropower station project in the world. It provides an efficient tool for quick judgment of unstable blocks, and ensure the safety of construction.
Some new theory and methods for development of slope rock block stability analysis system are presented in this paper. Being different from others, in the theory a cutting method is used to set up a block model by which the problem of complicated geometry shapes, such as hexahedron blocks can be solved. Theoretically, this method can be generally used for evaluating the stability of wedge-blocks with arbitrary geometric shapes. A software package based on above theory has been developed in the environment of Windows 3.x and Windows 95. As a typical example, the new theory and software have been applied to stability analysis of wedge slope at shiplock high slopes in Three-Gorges Project, the far hydropower station project in the world. It provides an efficient tool for quick judgment of unstable blocks, and ensure the safety of construction.
2001, 9(4): 414-417.
In this paper, the karst collapse is classified into two types. One is the collapse of the roof of karst cave in limestone and another is the collapse of the roof of earth cave in cover formed by the movement of karstic groundwater. Furthermore, the later is also distinguished into two kinds, one is the collapse of clayey cave and another is the collapse of sandy cave. The formation mechanism of every type of karst collapse is expounded. The karst collapse occurring in Wuhan just is the collapse of sandy caves. The paper points out that the basic approach to prevent and control the collapses is to understand the cause for their formation. At first, one should clarify the destribution of karstitied limestone, especially the area in which the limestone is covered directly by sand layer is generally potential to collapse so it may be regarded as a high dangrous area. Secondly, it is necesary to understand the movement of karstic groundwater, especially the dynamic factor causing serious vertical variation of karst groundwater table, such as water puming from a deep well. To remove the dynamic factor could prevent the collapses essentially. The effective countermeasure to treat collapse pits seggested in the paper is filling up them and sealling up their passage to karst piping.
In this paper, the karst collapse is classified into two types. One is the collapse of the roof of karst cave in limestone and another is the collapse of the roof of earth cave in cover formed by the movement of karstic groundwater. Furthermore, the later is also distinguished into two kinds, one is the collapse of clayey cave and another is the collapse of sandy cave. The formation mechanism of every type of karst collapse is expounded. The karst collapse occurring in Wuhan just is the collapse of sandy caves. The paper points out that the basic approach to prevent and control the collapses is to understand the cause for their formation. At first, one should clarify the destribution of karstitied limestone, especially the area in which the limestone is covered directly by sand layer is generally potential to collapse so it may be regarded as a high dangrous area. Secondly, it is necesary to understand the movement of karstic groundwater, especially the dynamic factor causing serious vertical variation of karst groundwater table, such as water puming from a deep well. To remove the dynamic factor could prevent the collapses essentially. The effective countermeasure to treat collapse pits seggested in the paper is filling up them and sealling up their passage to karst piping.
2001, 9(4): 418-423.
The shortage of water resource has seriously hindered the economic development in Guangxi rural areas. This paper dirstly pays attention to the distribution characteristics of water resources in karstic areas and the problems arisen from the water explortation. Then the author analyzes the current and longterm requirements for water resource and finally puts forward a new idea of exploitation and utlization of water resource in karst areas in future.
The shortage of water resource has seriously hindered the economic development in Guangxi rural areas. This paper dirstly pays attention to the distribution characteristics of water resources in karstic areas and the problems arisen from the water explortation. Then the author analyzes the current and longterm requirements for water resource and finally puts forward a new idea of exploitation and utlization of water resource in karst areas in future.
2001, 9(4): 424-428.
Geotechnical engineering aspects relate to solid waste disposal, including investigation, prevention and remedy of geological disasters, test and research on characteristics of soil-like waste and non-soil waste, statility and deformation analysis of landfill field and filled waste are systematically introduceed in this paper. Regularities of landfill field leakage and pollution transportion, investigation and surveying of clay and materials for dam construction are also discussed.
Geotechnical engineering aspects relate to solid waste disposal, including investigation, prevention and remedy of geological disasters, test and research on characteristics of soil-like waste and non-soil waste, statility and deformation analysis of landfill field and filled waste are systematically introduceed in this paper. Regularities of landfill field leakage and pollution transportion, investigation and surveying of clay and materials for dam construction are also discussed.
2001, 9(4): 429-434.
The large-scale economic development in Western China will provide unprecedented opportunity and new challenge for railway construction. In this paper a detailed discussion is made on the problems arisen from the railway construction in the aspects of specific geological conditions and geo-environment in Western China. The discussion on the problems provideds a necessary reference for railway construction.
The large-scale economic development in Western China will provide unprecedented opportunity and new challenge for railway construction. In this paper a detailed discussion is made on the problems arisen from the railway construction in the aspects of specific geological conditions and geo-environment in Western China. The discussion on the problems provideds a necessary reference for railway construction.
2001, 9(4): 435-442.
Coupling Theory (CT) is a fundamental theory of engineering geology and can be found in every field of engineering geology . It is also a basic guiding index for solving various engineering-geological problems. Its basicthinking way is to make an optimum coupling between engineering system and natural geological system in the process of engineering investigation, design and construction. In this paper an introduction is made to the basic points of CT, including the graphic model, mathematical model, performance steps, cycle and decision-making criteria of the coupling theory, couping degree and risk analysis, and the relationship between coupling theory and other subject, etc.
Coupling Theory (CT) is a fundamental theory of engineering geology and can be found in every field of engineering geology . It is also a basic guiding index for solving various engineering-geological problems. Its basicthinking way is to make an optimum coupling between engineering system and natural geological system in the process of engineering investigation, design and construction. In this paper an introduction is made to the basic points of CT, including the graphic model, mathematical model, performance steps, cycle and decision-making criteria of the coupling theory, couping degree and risk analysis, and the relationship between coupling theory and other subject, etc.
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