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Editor Work2007 Vol. 15, No. 2
Previous Issue
2007, 15(2): 145-153.
Abstract
Research on soil mass structural system is a comprehensive and interdisciplinary fundamental work which is of great theoretical and practical significance. It covers the whole soil mass system from macroscopic soil distribution area down to microscopic particulates from the angle of length scale. According to the principle that soil property changes with its corresponding length scale, soil mass structural system is divided into seven different structural hierarchies from macro to micro scopes in this paper. The significance, contents and research methodology of each hierarchy is explained. After the analysis on scientific meaning of a hierarchical division, several key subjects which will be met with in future research are introduced. Combining soil mechanics and engineering geology together tightly, the hierarchical division of soil mass structural system has not only cleared off some ambiguous understanding during the engineering property research of soil mass, but also laid a firm foundation for comprehensive and systematic research.
Research on soil mass structural system is a comprehensive and interdisciplinary fundamental work which is of great theoretical and practical significance. It covers the whole soil mass system from macroscopic soil distribution area down to microscopic particulates from the angle of length scale. According to the principle that soil property changes with its corresponding length scale, soil mass structural system is divided into seven different structural hierarchies from macro to micro scopes in this paper. The significance, contents and research methodology of each hierarchy is explained. After the analysis on scientific meaning of a hierarchical division, several key subjects which will be met with in future research are introduced. Combining soil mechanics and engineering geology together tightly, the hierarchical division of soil mass structural system has not only cleared off some ambiguous understanding during the engineering property research of soil mass, but also laid a firm foundation for comprehensive and systematic research.
2007, 15(2): 154-158.
After the Three Gorges dam begins its full functions, the fields of stress and dynamics of ground water in the soil and rock mass will have great changes. If other external agents such as change of water level, erosion of wind wave and rainstorm emerge, the stability of the bank slopes will be changed too. It even can cause banks to collapse. In order to research the modes of the bank collapse and the formation mechanism, this paper develops the conditions of geology and climate of the Three Gorges in a model test. Then, using the method of physical modelling and the principle of orthogonal design, this paper develops the relations and sensitivity between the pattern and width of bank collapse and factors including slope angle, water level, rainfall intensity, earthiness and wave.
After the Three Gorges dam begins its full functions, the fields of stress and dynamics of ground water in the soil and rock mass will have great changes. If other external agents such as change of water level, erosion of wind wave and rainstorm emerge, the stability of the bank slopes will be changed too. It even can cause banks to collapse. In order to research the modes of the bank collapse and the formation mechanism, this paper develops the conditions of geology and climate of the Three Gorges in a model test. Then, using the method of physical modelling and the principle of orthogonal design, this paper develops the relations and sensitivity between the pattern and width of bank collapse and factors including slope angle, water level, rainfall intensity, earthiness and wave.
2007, 15(2): 159-163.
It is important for rock engineering such as nuclear waste disposal, slope stability, mining engineering and hydropower project to describe quantitatively the distribution of geological faults. A distribution diagram of faults is obtained from the geological diagram at Zipingpu Hydropower Project. The data set of 126 faults at the site is analyzed statistically. The fault lengths are found to have a distribution of three orders of magnitudes. . A power-law relation between the fault number and the fault length is proposed, i.e., N(r)~r-D. Two power exponents are estimated by using linear fit in two segments. It is found that the power exponent has a value of 0.32 if faslt lengths are shorter than 2.5km. The power exponent is equal to 1.58 if fault lengths are longer than 2.5 km. It is suggested that the power-law relation between fault number and fault length is of a significant importance for extrapolation of a fault distribution to either further small or further large scales.
It is important for rock engineering such as nuclear waste disposal, slope stability, mining engineering and hydropower project to describe quantitatively the distribution of geological faults. A distribution diagram of faults is obtained from the geological diagram at Zipingpu Hydropower Project. The data set of 126 faults at the site is analyzed statistically. The fault lengths are found to have a distribution of three orders of magnitudes. . A power-law relation between the fault number and the fault length is proposed, i.e., N(r)~r-D. Two power exponents are estimated by using linear fit in two segments. It is found that the power exponent has a value of 0.32 if faslt lengths are shorter than 2.5km. The power exponent is equal to 1.58 if fault lengths are longer than 2.5 km. It is suggested that the power-law relation between fault number and fault length is of a significant importance for extrapolation of a fault distribution to either further small or further large scales.
2007, 15(2): 164-168.
The deposit layer in Yalong river bed is usually over 30 m thick and can be thick up to 51.6 m. The deposit thickness varies substantially horizontal direction. The deposit layer can be divided into three parts along the depth. The upper and lower parts are normal river faces, while the middle part is composed of alluvial, pluvial, barrier lacustrine, fluvial-glacial and comparatively thick. The underlain bedrock has a 20 m thick unloaded and relaxed zone. This zone has weak weathering, high permeability, poor integrality and poor engineering-mechanics features. It has an engineering implication in dam construction since it can be a leakage zone beneath dam base. The thick deposit layer was resulted from a second series of deposition. The unloaded and relaxed zone is due to the fact that the river bed was formed 25000 years ago, which had adequate time for the bedrock to unload, relax, and be weathered.
The deposit layer in Yalong river bed is usually over 30 m thick and can be thick up to 51.6 m. The deposit thickness varies substantially horizontal direction. The deposit layer can be divided into three parts along the depth. The upper and lower parts are normal river faces, while the middle part is composed of alluvial, pluvial, barrier lacustrine, fluvial-glacial and comparatively thick. The underlain bedrock has a 20 m thick unloaded and relaxed zone. This zone has weak weathering, high permeability, poor integrality and poor engineering-mechanics features. It has an engineering implication in dam construction since it can be a leakage zone beneath dam base. The thick deposit layer was resulted from a second series of deposition. The unloaded and relaxed zone is due to the fact that the river bed was formed 25000 years ago, which had adequate time for the bedrock to unload, relax, and be weathered.
2007, 15(2): 169-173.
Based on the field investigation in Wudongde valley of the Jingshajiang River, and comparative analysis of available data from drills, silos and galleries in the different parts of the Jinpingzi debris deposits of the Wudongde valley, the basic features and original types of the debris deposits were investigated. Geomorphological, sedimentological and chronological analyses of debris deposits infilling the Jinpingzi reaches of Wudongde valley, are used to elucidate the geomorphologic evolution and stability of debris deposits. Thermoluminescence (TL) dating provides a temporal frame for the process of the river incision and fluvial sedimentation in the past. The samples in the bottom and in the top of the deposits give the TL ages of ca.1979.70 KaBP. and 86.617.36 KaBP., respectively, implying that the forming of the deposits took about 110 Ka. The Jinpingzi debris deposits were not due to landslides They were formed during three different phases of the geomorphic process of the river and formed thick layers of alluvia and collapsed cumuli. The Jinpingzi debris deposts are in a stable condition and would not affect the selection of the site for Wudongde hydropower station.
Based on the field investigation in Wudongde valley of the Jingshajiang River, and comparative analysis of available data from drills, silos and galleries in the different parts of the Jinpingzi debris deposits of the Wudongde valley, the basic features and original types of the debris deposits were investigated. Geomorphological, sedimentological and chronological analyses of debris deposits infilling the Jinpingzi reaches of Wudongde valley, are used to elucidate the geomorphologic evolution and stability of debris deposits. Thermoluminescence (TL) dating provides a temporal frame for the process of the river incision and fluvial sedimentation in the past. The samples in the bottom and in the top of the deposits give the TL ages of ca.1979.70 KaBP. and 86.617.36 KaBP., respectively, implying that the forming of the deposits took about 110 Ka. The Jinpingzi debris deposits were not due to landslides They were formed during three different phases of the geomorphic process of the river and formed thick layers of alluvia and collapsed cumuli. The Jinpingzi debris deposts are in a stable condition and would not affect the selection of the site for Wudongde hydropower station.
2007, 15(2): 174-178.
A unstable rock block has been identified at the Xilongchi reservoir. It is named as the BW2 dangerous rock block because it threatens the safety of the reservoir. It was cut by F118 fault into column. The paper presents a systematical and detailed description of the site engineering geological conditions. Based on the analysis, it proposes the possible failure models. The Fast Lagrangian Analysis of Continua method （FLAC3D） and the limit equilibrium method are applied to forecast the deformation and stability of the BW2 dangerous rock. The treatment measures are suggested accordingly.
A unstable rock block has been identified at the Xilongchi reservoir. It is named as the BW2 dangerous rock block because it threatens the safety of the reservoir. It was cut by F118 fault into column. The paper presents a systematical and detailed description of the site engineering geological conditions. Based on the analysis, it proposes the possible failure models. The Fast Lagrangian Analysis of Continua method （FLAC3D） and the limit equilibrium method are applied to forecast the deformation and stability of the BW2 dangerous rock. The treatment measures are suggested accordingly.
2007, 15(2): 179-185.
This paper argues that prediction capability of spatial distributions of geologic hazards on slopes is the prerequisite and the successful key for controlling, monitoring and warning of geologic hazards in mountainous regions. It then discusses the problems on the connotation and working procedures of the prediction of slope geologic hazard, failure types of the slopes, structural types of the slopes, environment condition and effect of human action.In the definition of slope geologic hazard, the prediction period is limited within the time period of engineering guarantee quality. And the prerequisite is to keep the existing slope structures, the environment conditions, as well as the effect of foreseeable human actions no change. First the procedure is to predict slope stability, and then to predict the hazard danger for slopes with bad or potential instability. Classification of failure types of slopes should take scale at a time seriously and combine the formation cause and structural types of slope. This has the guiding meaning for geological investigation and research. To show control sense of the formation cause and structural type to stability, the paper provides new type systems of clastic rock and parametamorphic rock slopes in the Three Gorge Project in Yangtze River and western region of China, and simply compares the typical textural characteristics and stability for three types of soil slopes. About the quantified research on environment effect for slope stability, the authors value natural mode observations and landslide inverse computation of many non-self-slopes. In addition the authors suggest to establish the definite geological modes based on the accurate field investigation, and to make quantification analysis of factors at a time and cell analysis using correlation principles of basic subjects, in order to expose more the mechanism of deformation and failure of slopes.
This paper argues that prediction capability of spatial distributions of geologic hazards on slopes is the prerequisite and the successful key for controlling, monitoring and warning of geologic hazards in mountainous regions. It then discusses the problems on the connotation and working procedures of the prediction of slope geologic hazard, failure types of the slopes, structural types of the slopes, environment condition and effect of human action.In the definition of slope geologic hazard, the prediction period is limited within the time period of engineering guarantee quality. And the prerequisite is to keep the existing slope structures, the environment conditions, as well as the effect of foreseeable human actions no change. First the procedure is to predict slope stability, and then to predict the hazard danger for slopes with bad or potential instability. Classification of failure types of slopes should take scale at a time seriously and combine the formation cause and structural types of slope. This has the guiding meaning for geological investigation and research. To show control sense of the formation cause and structural type to stability, the paper provides new type systems of clastic rock and parametamorphic rock slopes in the Three Gorge Project in Yangtze River and western region of China, and simply compares the typical textural characteristics and stability for three types of soil slopes. About the quantified research on environment effect for slope stability, the authors value natural mode observations and landslide inverse computation of many non-self-slopes. In addition the authors suggest to establish the definite geological modes based on the accurate field investigation, and to make quantification analysis of factors at a time and cell analysis using correlation principles of basic subjects, in order to expose more the mechanism of deformation and failure of slopes.
2007, 15(2): 186-192.
Liujiapo landslide is located at the northern Langao County of Shanxi Province. It is a landslide of loose deposits type. The slide is consisted of clayey gravelly sand with low permeability. The sand is easy to occur seepage deformation under the dynamic hydraulic pressure. Mud-slate and schist with shallow weathering depth constitutes the bedrock under the landslide. So the difference in the engineering properties between the sliding mass and the sliding bed is evident. . The interface is the main slip face of the landslide. The landslide is an old that had occurred to deformation and slide many times. Removement of the landslide resulted from influence factors such as continual strong rainfall and cut slope so on in 2003. The landslide is unsteady at present. If it encounters strong rainfall, it will occur to lose its integer stability. The survey for regional landslide shows that Liujiapo landslide can be a representative in southern Qinling in terms of landslide type or substance composition and deformation rule.
Liujiapo landslide is located at the northern Langao County of Shanxi Province. It is a landslide of loose deposits type. The slide is consisted of clayey gravelly sand with low permeability. The sand is easy to occur seepage deformation under the dynamic hydraulic pressure. Mud-slate and schist with shallow weathering depth constitutes the bedrock under the landslide. So the difference in the engineering properties between the sliding mass and the sliding bed is evident. . The interface is the main slip face of the landslide. The landslide is an old that had occurred to deformation and slide many times. Removement of the landslide resulted from influence factors such as continual strong rainfall and cut slope so on in 2003. The landslide is unsteady at present. If it encounters strong rainfall, it will occur to lose its integer stability. The survey for regional landslide shows that Liujiapo landslide can be a representative in southern Qinling in terms of landslide type or substance composition and deformation rule.
2007, 15(2): 193-199.
Huashiban landslide is located at the down Tiger-Leap-Gorge along the left bank of Jinshajiang river. It has caught wide attention because it obstructed the Jinshajiang river and destroyed the road on Oct. 28, 1996. The field work revealed that the landslide is a typical consequent rock landslide. The thick stratified limestone in the slope was cut into different diamond blocks by bedding plane and two steep sets joints. The original safe state of diamond blocks were transformed into unsafe state as suspended blocks due to many factors such as weathering, gravity, rainfall and road construction. Furthermore, the rock blocks present as step-like suspended blocks for the sidelong relation of the strikes of slope and strata. At the more outside of the slope, the blocks are more unstable. Therefore, the landslide is characterized by collapses of rock blocks with different sizes and can occur from time to time.
Huashiban landslide is located at the down Tiger-Leap-Gorge along the left bank of Jinshajiang river. It has caught wide attention because it obstructed the Jinshajiang river and destroyed the road on Oct. 28, 1996. The field work revealed that the landslide is a typical consequent rock landslide. The thick stratified limestone in the slope was cut into different diamond blocks by bedding plane and two steep sets joints. The original safe state of diamond blocks were transformed into unsafe state as suspended blocks due to many factors such as weathering, gravity, rainfall and road construction. Furthermore, the rock blocks present as step-like suspended blocks for the sidelong relation of the strikes of slope and strata. At the more outside of the slope, the blocks are more unstable. Therefore, the landslide is characterized by collapses of rock blocks with different sizes and can occur from time to time.
2007, 15(2): 200-204.
According to the national standards, the earth load on a landslide retaining structure is based on the inter-slice force of transmitting coefficient method. The paper analyzes the problems of the current method in the calculation of the load on a landslide retaining structure and then puts out a new method for the calculation. The new method is based on on the slope stability analysis. This new method can remedy the defects associated with the current method adopted in the national standards.
According to the national standards, the earth load on a landslide retaining structure is based on the inter-slice force of transmitting coefficient method. The paper analyzes the problems of the current method in the calculation of the load on a landslide retaining structure and then puts out a new method for the calculation. The new method is based on on the slope stability analysis. This new method can remedy the defects associated with the current method adopted in the national standards.
2007, 15(2): 205-211.
This paper incorporates the Morgenstern-Price method with the Monte-carlo simulation for reliability analysis of slope stability. The approach is further applied to the reliability analysis of the slope stability of the downstream levee on the Yellow River in Kaifeng. Sampling method is used in the reliability analysis. The spatial variability of soil parameters is taken into consideration. The paper further discusses the effects of the correlation of soil parameters on the reliability index. Some more reasonable results are obtained. The approach and results presented in this paper are useful to the safety evaluation of slopes on Yellow River.
This paper incorporates the Morgenstern-Price method with the Monte-carlo simulation for reliability analysis of slope stability. The approach is further applied to the reliability analysis of the slope stability of the downstream levee on the Yellow River in Kaifeng. Sampling method is used in the reliability analysis. The spatial variability of soil parameters is taken into consideration. The paper further discusses the effects of the correlation of soil parameters on the reliability index. Some more reasonable results are obtained. The approach and results presented in this paper are useful to the safety evaluation of slopes on Yellow River.
2007, 15(2): 212-216.
A reasonable soil constitutive model is one of the key aspects for the land subsidence simulation. Based on the data from layered marks of Shanghai and Changzhou region, the results indicate that the rheology occurs in the sandy soil. In order to investigate the lag phenomena between the deformation in the land subsidence and the variation of the water level of the aquifer, the creep behavior of the saturated sand is studied based on the uniaxial compression tests of undisturbed soils of the 1st, 2nd confined aquifers in Changzhou City. Based on visco-elastic theory, inverse models of creep curves of load tests were set up for Merchant and Burgers model. The analysis results show that the optimum rheological model is Burgers model for different load test curves. The relation between the rheological parameters and applied normal loads were analyzed and discussed.
A reasonable soil constitutive model is one of the key aspects for the land subsidence simulation. Based on the data from layered marks of Shanghai and Changzhou region, the results indicate that the rheology occurs in the sandy soil. In order to investigate the lag phenomena between the deformation in the land subsidence and the variation of the water level of the aquifer, the creep behavior of the saturated sand is studied based on the uniaxial compression tests of undisturbed soils of the 1st, 2nd confined aquifers in Changzhou City. Based on visco-elastic theory, inverse models of creep curves of load tests were set up for Merchant and Burgers model. The analysis results show that the optimum rheological model is Burgers model for different load test curves. The relation between the rheological parameters and applied normal loads were analyzed and discussed.
2007, 15(2): 217-221.
Shear strength of rock discontinuities is an important parameter in landslide prevention . It is necessary to study the effects of the two shear strength parameters, i.e., the cohesion c and the internal friction angle , in order to choose a suitable method for determining the shear strength parameter values of rock discontinuities. This paper focuses on the effects of the shear strength parameters of control discontinuities on the stability of rock slopes from 10 to 30 m high, where the limit equilibrium theory is used. The results show that the effect of the cohesion reduces with increasing in slope height and the effect of the internal friction angle increases with increasing in slope height. A group of curves are presented. The effect of the cohesion and the effect of the internal friction angle are equivalent on the curves. The effects of the cohesion c and internal friction angle on slope stability can be easily analyzied with the aid of the curves.
Shear strength of rock discontinuities is an important parameter in landslide prevention . It is necessary to study the effects of the two shear strength parameters, i.e., the cohesion c and the internal friction angle , in order to choose a suitable method for determining the shear strength parameter values of rock discontinuities. This paper focuses on the effects of the shear strength parameters of control discontinuities on the stability of rock slopes from 10 to 30 m high, where the limit equilibrium theory is used. The results show that the effect of the cohesion reduces with increasing in slope height and the effect of the internal friction angle increases with increasing in slope height. A group of curves are presented. The effect of the cohesion and the effect of the internal friction angle are equivalent on the curves. The effects of the cohesion c and internal friction angle on slope stability can be easily analyzied with the aid of the curves.
2007, 15(2): 222-227.
The mechanical behaviour and variations in weathered rock structural components is very important to the stability, durability and protection of ancient rock buildings and bridges. This paper studies the variations of the compressive strength and the elastic modulus with depth in weathered rock blocks. The weathered rock blocks are the rock structural components of the Ancient Moon Bridge. It uses the sound wave in-situ testing technique and the laboratory tests because of the facts that weathered rock sample is hard to get from the ancient bridge the weathered rock samples are easy to break during sampling, and that the laboratory test can only get the mechanical parameters of an entire rock sample and cannot finds the gradual variation of the mechanical parameters along the depth of the weathered rock zone. The results indicate that the compressive strength and the elastic modulus ratio are inverse functions of exponent with respect to the depth from the weathered rock surface to the un-weathered rock zone.
The mechanical behaviour and variations in weathered rock structural components is very important to the stability, durability and protection of ancient rock buildings and bridges. This paper studies the variations of the compressive strength and the elastic modulus with depth in weathered rock blocks. The weathered rock blocks are the rock structural components of the Ancient Moon Bridge. It uses the sound wave in-situ testing technique and the laboratory tests because of the facts that weathered rock sample is hard to get from the ancient bridge the weathered rock samples are easy to break during sampling, and that the laboratory test can only get the mechanical parameters of an entire rock sample and cannot finds the gradual variation of the mechanical parameters along the depth of the weathered rock zone. The results indicate that the compressive strength and the elastic modulus ratio are inverse functions of exponent with respect to the depth from the weathered rock surface to the un-weathered rock zone.
2007, 15(2): 228-232.
The method of displacement back-analysis bridges between theory and practice, and provides a feasible and effective method for design and construction of rock engineering works. For resolving the problems about geological exploration, design and construction and reducing risk, the dynamic displacement back-analysis mode is established for advancing service tunnel. Based on the information feedbacks and forecasting the geology of main tunnel and judging the stability of surrounding rocks, the detailed measures and schemes for design and construction is proposed for the main tunnel. As necessary, adjustments and variations on the preliminary design parameters and schemes of the tunnel lining during construction are carried out. The timely feedbacking between design and construction contributes an effective method for successful tunneling below the sea water.
The method of displacement back-analysis bridges between theory and practice, and provides a feasible and effective method for design and construction of rock engineering works. For resolving the problems about geological exploration, design and construction and reducing risk, the dynamic displacement back-analysis mode is established for advancing service tunnel. Based on the information feedbacks and forecasting the geology of main tunnel and judging the stability of surrounding rocks, the detailed measures and schemes for design and construction is proposed for the main tunnel. As necessary, adjustments and variations on the preliminary design parameters and schemes of the tunnel lining during construction are carried out. The timely feedbacking between design and construction contributes an effective method for successful tunneling below the sea water.
2007, 15(2): 233-236.
Ground subsidence is one of the common geological disasters that have often been reported. From 1990s, the engineering environmental changes in Shanghai have become a new cause of inducing ground subsidence. There are many factors affecting the process of ground subsidence induced by external loadings. Such process cannot be explicitly presented with simple mathematical expressions, but it is not totally unknown like a black box, in terms of the internal structure, parameters, and characteristics. Therefore, the grey theory can be applied to the prediction of the ground subsidence. According to the characteristic of unequal time-interval of monitoring and observation, the unequal time-interval grey model GM (1, 1) is used to predict the subsidence of a certain high-rising building in the Lujiazui area of Shanghai and the predicted result is compared with the monitored data. The subsidence of the indoor model test is also predicted with this theory. The observed data are compared with the predicted data with the adaptive neuro-fuzzy inference system (ANFIS). The result indicates that the unequal time-interval GM (1, 1) is reasonable and accurate to predict the ground subsidence induced by engineering works.
Ground subsidence is one of the common geological disasters that have often been reported. From 1990s, the engineering environmental changes in Shanghai have become a new cause of inducing ground subsidence. There are many factors affecting the process of ground subsidence induced by external loadings. Such process cannot be explicitly presented with simple mathematical expressions, but it is not totally unknown like a black box, in terms of the internal structure, parameters, and characteristics. Therefore, the grey theory can be applied to the prediction of the ground subsidence. According to the characteristic of unequal time-interval of monitoring and observation, the unequal time-interval grey model GM (1, 1) is used to predict the subsidence of a certain high-rising building in the Lujiazui area of Shanghai and the predicted result is compared with the monitored data. The subsidence of the indoor model test is also predicted with this theory. The observed data are compared with the predicted data with the adaptive neuro-fuzzy inference system (ANFIS). The result indicates that the unequal time-interval GM (1, 1) is reasonable and accurate to predict the ground subsidence induced by engineering works.
2007, 15(2): 237-243.
Panzhihua airport was constructed in an area with complicated topographical and geological conditions and therefore involved a large amount of excavation and filling works. At present, the settlement and landslide in filled land and slopes are substantial and cause the many problems for safe and smooth operation of the airport facilities. This paper presents the basic characters and causes of the landslides in the fill slopes. Based on the back-analysis and trial results, the paper ascertains the shear strength parameters at the shear plane of the slope deformation, and analyses the sensitivity that the shear strength parameters can make for the changes of the slope stability. Furthermore, on the basis of the landslide thrust calculation, the paper contrasts and demonstrates each remediation measure, and establishes a comprehensive remediation scheme which includes anti-slide piles, prestressed ground anchors with reinforced concrete beams on the surface, trimming back slopes and provision of surface drainages.
Panzhihua airport was constructed in an area with complicated topographical and geological conditions and therefore involved a large amount of excavation and filling works. At present, the settlement and landslide in filled land and slopes are substantial and cause the many problems for safe and smooth operation of the airport facilities. This paper presents the basic characters and causes of the landslides in the fill slopes. Based on the back-analysis and trial results, the paper ascertains the shear strength parameters at the shear plane of the slope deformation, and analyses the sensitivity that the shear strength parameters can make for the changes of the slope stability. Furthermore, on the basis of the landslide thrust calculation, the paper contrasts and demonstrates each remediation measure, and establishes a comprehensive remediation scheme which includes anti-slide piles, prestressed ground anchors with reinforced concrete beams on the surface, trimming back slopes and provision of surface drainages.
2007, 15(2): 244-248.
The anchored segment of anti-sliding pile is often assumed as the Winkler elastic subgrade beam for internal force calculation. Based on the power series solution, the traditional foundation coefficient m or K method is applied by using the calculation tables. The calculation procedure is complicated and errors can take place easily because of cut off errors of the coefficients in the tables. Finite difference method is a rational method, but needs the iteration and test calculation methods and more segment number. Based on the foundation coefficient m(k) method, this paper derives the counter force loading calculation formula to analyze internal forces of anchored segment. Compared with the finite difference method, the present method has less segment number and does not need the iteration and test calculation method. The method of controlling its calculation precision is proposed. The calculation program of internal forces for a whole pile is designed. An example is given and shows that this proposed method can improve the calculation efficiency of internal forces of anti-sliding pile and its precision effectively. It can advantage the optimization design for the structure of anti-sliding piles.
The anchored segment of anti-sliding pile is often assumed as the Winkler elastic subgrade beam for internal force calculation. Based on the power series solution, the traditional foundation coefficient m or K method is applied by using the calculation tables. The calculation procedure is complicated and errors can take place easily because of cut off errors of the coefficients in the tables. Finite difference method is a rational method, but needs the iteration and test calculation methods and more segment number. Based on the foundation coefficient m(k) method, this paper derives the counter force loading calculation formula to analyze internal forces of anchored segment. Compared with the finite difference method, the present method has less segment number and does not need the iteration and test calculation method. The method of controlling its calculation precision is proposed. The calculation program of internal forces for a whole pile is designed. An example is given and shows that this proposed method can improve the calculation efficiency of internal forces of anti-sliding pile and its precision effectively. It can advantage the optimization design for the structure of anti-sliding piles.
2007, 15(2): 249-252.
Key block of the rock mass slope takes important role in safety analysis and support design. Considering many factors impacting on the stability of the key block, the paper uses orthogonal experiment design method to analyze the sensitivity of the significant factors which have influence on the stability of key block, and evaluates the degree of the influence of different physical and mechanical parameters on the safety factor of the key block. Then the rational advice is provided for the project.
Key block of the rock mass slope takes important role in safety analysis and support design. Considering many factors impacting on the stability of the key block, the paper uses orthogonal experiment design method to analyze the sensitivity of the significant factors which have influence on the stability of key block, and evaluates the degree of the influence of different physical and mechanical parameters on the safety factor of the key block. Then the rational advice is provided for the project.
2007, 15(2): 253-257.
The rock masses comprising the slope at the portal of a twin-arched tunnel in the town of Fuxi, Anhui province are strongly affected by weathering and unloading. Before excavation, the slope had noticeable down-slope deformation at its middle and upper levels and the deofrmation was in the state of limit equilibrium. On the basis of the site investigation and the study of the rock mass structures, the paper esbalishes the deformation mode and failure mechanism of the slope. Furthermore, the paper simulates the deformation character FLAC3D. The deformation analysis leads the design measure that uses grout to stabilize the rock masses. The result of calculations indicates that the slope can have better stability after grouting. In the meanwhile, the monitored data also shows that the stability of the grouted slope is better than that of the slope before grouting. This can ensure that the expressway will be safe during the road construction and its long-term usage.
The rock masses comprising the slope at the portal of a twin-arched tunnel in the town of Fuxi, Anhui province are strongly affected by weathering and unloading. Before excavation, the slope had noticeable down-slope deformation at its middle and upper levels and the deofrmation was in the state of limit equilibrium. On the basis of the site investigation and the study of the rock mass structures, the paper esbalishes the deformation mode and failure mechanism of the slope. Furthermore, the paper simulates the deformation character FLAC3D. The deformation analysis leads the design measure that uses grout to stabilize the rock masses. The result of calculations indicates that the slope can have better stability after grouting. In the meanwhile, the monitored data also shows that the stability of the grouted slope is better than that of the slope before grouting. This can ensure that the expressway will be safe during the road construction and its long-term usage.
2007, 15(2): 258-262.
The BEAM is a new kind of electrical method that is used in advanced geological exploration during tunneling It has been rarely used in China. This paper firstly introduces the operation principle of the BEAM technique, and then discusses the first application to the tunneling in TongLuo Mountain for Dian-Ling highway. The detailed work process and results are presented. Comparison among the results of BEAM, GPR, TSP and the actual case after cutting indicates that BEAM has a fairly good efficiency when there is ground water in the rock mass ahead of tunnel work face. At last, some advice is summarized on how to use this method in China.
The BEAM is a new kind of electrical method that is used in advanced geological exploration during tunneling It has been rarely used in China. This paper firstly introduces the operation principle of the BEAM technique, and then discusses the first application to the tunneling in TongLuo Mountain for Dian-Ling highway. The detailed work process and results are presented. Comparison among the results of BEAM, GPR, TSP and the actual case after cutting indicates that BEAM has a fairly good efficiency when there is ground water in the rock mass ahead of tunnel work face. At last, some advice is summarized on how to use this method in China.
2007, 15(2): 263-267.
Based on the tests and measurements at a high fill slope site, this paper utilizes the ng frequency spectrum analysis method and examines the characters and basic regular about how the blasting waves transmit in slope. The dynamic response of the fill slope is further analyzed with the modal superposition of finite-element method. Based on the two analysis methods, the damaged mode, the acceleration and displacement regulars of the slope surface are characterized.
Based on the tests and measurements at a high fill slope site, this paper utilizes the ng frequency spectrum analysis method and examines the characters and basic regular about how the blasting waves transmit in slope. The dynamic response of the fill slope is further analyzed with the modal superposition of finite-element method. Based on the two analysis methods, the damaged mode, the acceleration and displacement regulars of the slope surface are characterized.
2007, 15(2): 268-272.
Based on the different electrical resistivity characteristics between the slipped loess mass and the sliding loess bed of a landslide, the multi-purpose numerical direct-current electricity meter modeled WDJD-1 and the improved exploring electrode installment are used to measure the electrical resistivity values of losses masses above and below the sliding surface respectively. The tests are carried out in trenches and drill holes in theoriginal condition of loess stratum where landslide occurred. The test results show that the electronic resistivity test curves appear the phenomenon of exceptional jumping crossing the sliding zone. On the other hand, the change difference of the curves is not evident in the undisturbed loess stratum. This exceptionally change characteristic can be a characteristic signature to identify the sliding surface position in loess slopes. This survey method fully uses existing exploration engineering condition, it is simple in operation and can directly-observe test results. It has the potential for landslide investigation in loess slopes.
Based on the different electrical resistivity characteristics between the slipped loess mass and the sliding loess bed of a landslide, the multi-purpose numerical direct-current electricity meter modeled WDJD-1 and the improved exploring electrode installment are used to measure the electrical resistivity values of losses masses above and below the sliding surface respectively. The tests are carried out in trenches and drill holes in theoriginal condition of loess stratum where landslide occurred. The test results show that the electronic resistivity test curves appear the phenomenon of exceptional jumping crossing the sliding zone. On the other hand, the change difference of the curves is not evident in the undisturbed loess stratum. This exceptionally change characteristic can be a characteristic signature to identify the sliding surface position in loess slopes. This survey method fully uses existing exploration engineering condition, it is simple in operation and can directly-observe test results. It has the potential for landslide investigation in loess slopes.
2007, 15(2): 273-278.
The safety reliability of railway embankments in permafrost area largely depends on the thermal field and the erosion resistant of the embankment. The umbrellas such as awning above the embankment or shading plate on the embankment slope not only block the solar radiation directly onto the embankment and slope, but also prevent the embankment and slope from rain infiltration and snow accumulation, which can change the ground temperature and reduce the variation of the ground temperature and moisture contents. Such umbrella method can be effective and operational to prevent the embankment from permafrost degradation. In order to determine to the upper limit lift and the roadbed stability, this special embankment is modelled by applying one-dimension heat conduction equation in the paper. The modeling includes phase change, combines with temperature information and meteorologic report of the shading embankment. The field observation and modeled result have shown that the umbrella method is reliable and safe. This umbrella protection approach would be an effective measure to prevent the railway disease during operation.
The safety reliability of railway embankments in permafrost area largely depends on the thermal field and the erosion resistant of the embankment. The umbrellas such as awning above the embankment or shading plate on the embankment slope not only block the solar radiation directly onto the embankment and slope, but also prevent the embankment and slope from rain infiltration and snow accumulation, which can change the ground temperature and reduce the variation of the ground temperature and moisture contents. Such umbrella method can be effective and operational to prevent the embankment from permafrost degradation. In order to determine to the upper limit lift and the roadbed stability, this special embankment is modelled by applying one-dimension heat conduction equation in the paper. The modeling includes phase change, combines with temperature information and meteorologic report of the shading embankment. The field observation and modeled result have shown that the umbrella method is reliable and safe. This umbrella protection approach would be an effective measure to prevent the railway disease during operation.
2007, 15(2): 279-283.
How to build the three dimensional model of the geologic body quickly and truly is a difficult problem which lies in the front of the numerical simulation operators. Although the three-dimensional (3D) geoscience simulation software has good 3D geological modelling ability, it can be difficult to join the corresponding geological model established by 3D study simulation software with numerical simulation software because of the difference in data structures. A majority of CAD software have good data connection with the present numerical analysis software. This paper presents a study on how to use CAD software to establish 3D geological model for 3D visualization and numerical simulation purposes. The 3D modeling of some highway slopes in Yunnan is used an examples to illustrate this approach is convenient, accurate and reasonable.
How to build the three dimensional model of the geologic body quickly and truly is a difficult problem which lies in the front of the numerical simulation operators. Although the three-dimensional (3D) geoscience simulation software has good 3D geological modelling ability, it can be difficult to join the corresponding geological model established by 3D study simulation software with numerical simulation software because of the difference in data structures. A majority of CAD software have good data connection with the present numerical analysis software. This paper presents a study on how to use CAD software to establish 3D geological model for 3D visualization and numerical simulation purposes. The 3D modeling of some highway slopes in Yunnan is used an examples to illustrate this approach is convenient, accurate and reasonable.
2007, 15(2): 284-287.
As particular geological bodies, many paleo-sinkholes extensively develop and distribute in North-China-Type coalfields, This paper studies the model of water inrush for thick wall cylinder at side face of paleo-sinkholes in north-China-Type coalfields, This has great significance to the safety production of coalmines.
As particular geological bodies, many paleo-sinkholes extensively develop and distribute in North-China-Type coalfields, This paper studies the model of water inrush for thick wall cylinder at side face of paleo-sinkholes in north-China-Type coalfields, This has great significance to the safety production of coalmines.
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