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Editor Work2008 Vol. 16, No. 1
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2008, 16(1): 1-5.
Abstract
With the information disclosed by the riverbed bores and field investigation, the exact place of covered Longpan fault was identified in the adolescent valley of Jinsha River. Then the formation mechanism of the old Longpan ramp valley was figured out. In fact, Longpan fault was a reverse slip fault and the Baihanchang fault was a normal left-rotation fault. Due to the different vertical motions of the zones of fracture, the old ramp valley came into being. In the evolutionary period, thick deposits developed in the valley. Through the drill cores, an important phenomenon was revealed that the deposits had a well-regulated layered fabric and multi-type components. The regional geology shows that the layered deposits was a result of different sedimentary environments and the disparate components accorded very well with the corresponding new tectonic movements such as periodic mountain raising and glaciations in middle Pleistocene in this region.
With the information disclosed by the riverbed bores and field investigation, the exact place of covered Longpan fault was identified in the adolescent valley of Jinsha River. Then the formation mechanism of the old Longpan ramp valley was figured out. In fact, Longpan fault was a reverse slip fault and the Baihanchang fault was a normal left-rotation fault. Due to the different vertical motions of the zones of fracture, the old ramp valley came into being. In the evolutionary period, thick deposits developed in the valley. Through the drill cores, an important phenomenon was revealed that the deposits had a well-regulated layered fabric and multi-type components. The regional geology shows that the layered deposits was a result of different sedimentary environments and the disparate components accorded very well with the corresponding new tectonic movements such as periodic mountain raising and glaciations in middle Pleistocene in this region.
2008, 16(1): 6-10.
There is a bank slope of non-matrix structure at some planning Hydroelectric Power Station on the middle of the Jinsha River. The spread of the bank slope is extraordinary thick, which mainly composed with dolomatic brecciated accumulation body. The slope induced a massive block event in the middle of Jin-sha river. Based on the analysis of sample,it happened 19,000 years ago. The landslide investigation has shown that the ancient accumulation body slope is stable. There is no deformation indication and condition of destabilization of the whole slope.
There is a bank slope of non-matrix structure at some planning Hydroelectric Power Station on the middle of the Jinsha River. The spread of the bank slope is extraordinary thick, which mainly composed with dolomatic brecciated accumulation body. The slope induced a massive block event in the middle of Jin-sha river. Based on the analysis of sample,it happened 19,000 years ago. The landslide investigation has shown that the ancient accumulation body slope is stable. There is no deformation indication and condition of destabilization of the whole slope.
2008, 16(1): 11-16.
The landslide examined in this paper is located in a hydropower station reservoir in Mingjiang River. It is 0.5 km away from dam foundation. The bottom of Baishuizhai older landslide deposit was affected by Diexi Earthquake in 1933 and formed an old landslide (i.e., the examined landslide). The landslide had great deformation after water storage in 2001 at the normal level of 1475 m above sea level. Early in 2003, the water level of reservoir declined to 1470 m and the deformation had slowed down. The terrain and geology conditions were examined and combined with field investigation and analysis of the monitoring data. The increase of core pressure caused by water storage was considered as the major reason of the recovery of this old landslide. A 2D FLAC numerical modeling showed that when the water level changed from 1450m(before water storage)to 1475 m and then to 1470 m, the deformation of landslide had changes of relative smooth to increase dramatically, then to increase slowly down, respectively. Calculation of stability showed that, in the condition of 1475 m water level or earthquake, the coefficient of landslide stability is 0.9~0.99. It means the landslide would occur. In order to make the water level to normal, the landslide needs some remedial measures . The sliding-block with drainage is suggested to be the main method.
The landslide examined in this paper is located in a hydropower station reservoir in Mingjiang River. It is 0.5 km away from dam foundation. The bottom of Baishuizhai older landslide deposit was affected by Diexi Earthquake in 1933 and formed an old landslide (i.e., the examined landslide). The landslide had great deformation after water storage in 2001 at the normal level of 1475 m above sea level. Early in 2003, the water level of reservoir declined to 1470 m and the deformation had slowed down. The terrain and geology conditions were examined and combined with field investigation and analysis of the monitoring data. The increase of core pressure caused by water storage was considered as the major reason of the recovery of this old landslide. A 2D FLAC numerical modeling showed that when the water level changed from 1450m(before water storage)to 1475 m and then to 1470 m, the deformation of landslide had changes of relative smooth to increase dramatically, then to increase slowly down, respectively. Calculation of stability showed that, in the condition of 1475 m water level or earthquake, the coefficient of landslide stability is 0.9~0.99. It means the landslide would occur. In order to make the water level to normal, the landslide needs some remedial measures . The sliding-block with drainage is suggested to be the main method.
2008, 16(1): 17-21.
Cataclastic rock mass has dominant discontinuous medium features. There are a special rock mass along with reconnaissance and building of Hydropower in the west. The rock mass should be cataclastic rock mass because of small space between discontinuities. But the rock mass differs from the common cataclastic rock masses because it has high mechanical characteristics and likely continuous medium features. The rock mass has high modulus of deformation, high shear strength and high sound degree coefficient. It is hoped to have reference to other projects. Two examples are analyzed. A new method of available rock mass in hydropower project is obtained.
Cataclastic rock mass has dominant discontinuous medium features. There are a special rock mass along with reconnaissance and building of Hydropower in the west. The rock mass should be cataclastic rock mass because of small space between discontinuities. But the rock mass differs from the common cataclastic rock masses because it has high mechanical characteristics and likely continuous medium features. The rock mass has high modulus of deformation, high shear strength and high sound degree coefficient. It is hoped to have reference to other projects. Two examples are analyzed. A new method of available rock mass in hydropower project is obtained.
2008, 16(1): 22-26.
The red bed is a clastic sedimentary rock mainly deposit by red continental sedimentation, the rock property is mainly composed by sandstone, mudstone, siltstone and arenaceous shale.It is alternate for the soft rock and hard rock, in existence by alternating layers, the layer combines weak.had influenced by the regional structure,the layer has great torsion , fold and high angle fault. The mud stone in the red bed has the character of weak water permeability, stick up to airslake is weak,has obvious differential airslake and the speed of disaggregation is quickly. the red beds slope influenced by the interaction between rock with water will lead wedge instability,slope creep deformation and disintegration ect.
The red bed is a clastic sedimentary rock mainly deposit by red continental sedimentation, the rock property is mainly composed by sandstone, mudstone, siltstone and arenaceous shale.It is alternate for the soft rock and hard rock, in existence by alternating layers, the layer combines weak.had influenced by the regional structure,the layer has great torsion , fold and high angle fault. The mud stone in the red bed has the character of weak water permeability, stick up to airslake is weak,has obvious differential airslake and the speed of disaggregation is quickly. the red beds slope influenced by the interaction between rock with water will lead wedge instability,slope creep deformation and disintegration ect.
2008, 16(1): 27-31.
This paper is based on a hydro-power project. Many uniaxial compressive rheology test are conducted on rotten rock using an in-house made test apparatus. The creep model for the rotten rock is obtained. The rheological properties of the rock are analyzed from the test data. The test data were used for the project design.
This paper is based on a hydro-power project. Many uniaxial compressive rheology test are conducted on rotten rock using an in-house made test apparatus. The creep model for the rotten rock is obtained. The rheological properties of the rock are analyzed from the test data. The test data were used for the project design.
2008, 16(1): 32-36.
The resilience of subgrade soil is an important mechanical parameter in pavement design. The design value of subgrade soil intensity often adopts the modulus of resilience testing under the most disadvantageous season. The influence of the changes of water contents to subgrade soil intensity are not taken into account. This paper analyzes the law governing the variation of the subgrade soil resilient modulus with the season water contents. Lessons were drawn from pavement relative damage thought that different season create in design method of AASHTO. An equivalent subgrade soil resilient modulus formula is deduced. It is proposed that the design value of subgrade soil intensity replaces the most disadvantage season module with the equivalent subgrade soil modulus of resilience. The proposed method can advance non-deformability of soil base and integer design strength of asphalt pavement.
The resilience of subgrade soil is an important mechanical parameter in pavement design. The design value of subgrade soil intensity often adopts the modulus of resilience testing under the most disadvantageous season. The influence of the changes of water contents to subgrade soil intensity are not taken into account. This paper analyzes the law governing the variation of the subgrade soil resilient modulus with the season water contents. Lessons were drawn from pavement relative damage thought that different season create in design method of AASHTO. An equivalent subgrade soil resilient modulus formula is deduced. It is proposed that the design value of subgrade soil intensity replaces the most disadvantage season module with the equivalent subgrade soil modulus of resilience. The proposed method can advance non-deformability of soil base and integer design strength of asphalt pavement.
2008, 16(1): 37-41.
It is one of the key problems to identify strength parameters C and of structural planes controlling the stability of rock block in rock slope stability analysis. At present, the parameters are calculated with the linear weight method by linking length and non-linking length. It can cause an error about 40% with the actual strength values. This paper uses 11 sets of the linking ratio: 10%, 30%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% and 90%. Blocky samples with dimension of 20 cm10 cm5 cm are made using M15 mortar. Further, shear strength testing is carried out in laboratory. The non-linear testing curves between C and are obtained for eac of the control structural plane and the linking ratios. According to testing results, a method to calculate C and for the control structural plane is established, where the linking ratio and the safety grade of control engineering are also considered. It is named as the linking ratio method. In use of the method, the linking ratio of the control structural plane is to be measureed in-situ. The axial compressive strength and frictional angle of the intact rock can be obtained from conventional laboratory rock test. The linking ratio method can be used with ease. Calculated results are compared well with actual strength values.
It is one of the key problems to identify strength parameters C and of structural planes controlling the stability of rock block in rock slope stability analysis. At present, the parameters are calculated with the linear weight method by linking length and non-linking length. It can cause an error about 40% with the actual strength values. This paper uses 11 sets of the linking ratio: 10%, 30%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% and 90%. Blocky samples with dimension of 20 cm10 cm5 cm are made using M15 mortar. Further, shear strength testing is carried out in laboratory. The non-linear testing curves between C and are obtained for eac of the control structural plane and the linking ratios. According to testing results, a method to calculate C and for the control structural plane is established, where the linking ratio and the safety grade of control engineering are also considered. It is named as the linking ratio method. In use of the method, the linking ratio of the control structural plane is to be measureed in-situ. The axial compressive strength and frictional angle of the intact rock can be obtained from conventional laboratory rock test. The linking ratio method can be used with ease. Calculated results are compared well with actual strength values.
2008, 16(1): 42-46.
The rock structure planes with low to middle inclination angles at some dam regions in the southwest of china have the spatial orientation rule of tendency toward either upstream or downstream. According to the structure of the surface contact, the planes are first divided into two big kinds: the rigid structure and the weak structure. Among them, the rigid structure belongs to the crevasse. The weak structure surface, according to its material composition and the structure characteristic, may be subdivided into 3 sub-groups including the clod rock debris, the rock debris clamps mud, the mud clamps the rock debris. Along the direction perpendicular to the fault strikes and from high elevation to low elevation, the fault structural planes have a development pattern gradually changing from the mud clamps rock debris, to the rock debris clamps mud, to the clod rock debris and to? crevasse . Finally based on the analyzing of shear test data, classification and development pattern, this paper puts forward an index value of shearing strength.
The rock structure planes with low to middle inclination angles at some dam regions in the southwest of china have the spatial orientation rule of tendency toward either upstream or downstream. According to the structure of the surface contact, the planes are first divided into two big kinds: the rigid structure and the weak structure. Among them, the rigid structure belongs to the crevasse. The weak structure surface, according to its material composition and the structure characteristic, may be subdivided into 3 sub-groups including the clod rock debris, the rock debris clamps mud, the mud clamps the rock debris. Along the direction perpendicular to the fault strikes and from high elevation to low elevation, the fault structural planes have a development pattern gradually changing from the mud clamps rock debris, to the rock debris clamps mud, to the clod rock debris and to? crevasse . Finally based on the analyzing of shear test data, classification and development pattern, this paper puts forward an index value of shearing strength.
2008, 16(1): 47-52.
Saturated sand was looked as a soil-water two-phase medium. A fully coupled three-dimension effective-stress dynamic analysis software was developed on the basis of Biot's consolidation theory. Stone columns composite foundation was analyzed using software. The research shows that the reduced vibration effectiveness of stone columns is very remarkable, and the surface maximum horizontal vibration acceleration of stone columns composite foundation is bigger than that of natural foundation. Moreover, the stone columns can restrain settlement of foundation. The drainage effectiveness of stone columns is very remarkable. With decreasing of input earthquake acceleration, the dissipation of pore water pressure starts after the peak value has reached. The effective influence domain of stone columns is a circling platform with narrow upside and wide underside. The densification effectiveness of stone columns is remarkable. The excess pore water pressure ratio considering coupling effectiveness is smaller than that only considering some effectiveness or other. So the coupling effectiveness of stone columns should be considered when judging of anti-liquefaction capability of stone columns composite foundation.
Saturated sand was looked as a soil-water two-phase medium. A fully coupled three-dimension effective-stress dynamic analysis software was developed on the basis of Biot's consolidation theory. Stone columns composite foundation was analyzed using software. The research shows that the reduced vibration effectiveness of stone columns is very remarkable, and the surface maximum horizontal vibration acceleration of stone columns composite foundation is bigger than that of natural foundation. Moreover, the stone columns can restrain settlement of foundation. The drainage effectiveness of stone columns is very remarkable. With decreasing of input earthquake acceleration, the dissipation of pore water pressure starts after the peak value has reached. The effective influence domain of stone columns is a circling platform with narrow upside and wide underside. The densification effectiveness of stone columns is remarkable. The excess pore water pressure ratio considering coupling effectiveness is smaller than that only considering some effectiveness or other. So the coupling effectiveness of stone columns should be considered when judging of anti-liquefaction capability of stone columns composite foundation.
2008, 16(1): 53-58.
In order to perfectly consider the role of crack seepage in rock slope failure, on basis of numerical manifold method program with the function of crack propagation, the coupling mechanism of seepage and deformation is illustrated and the corresponding coupling equations are deduced from the viewpoint of minimum potential energy principle. The simulation of seepage and fracture is implemented in the program. This program is used to simulate the failure of rock slope with an initial crack under seepage load. The results show that the crack begins to propagate under the initial water pressure, and gradually runs through the rockmass to form the block. Therefore, the block breaks away the original rockmass under the action of gravity. Meanwhile, from the calculation of the stress intensity factor (SIF) in the crack propagation, it can be seen that the first SIF value is always larger than the second one. With calculation time going on, the difference between them becomes larger. Hence, the crack propagation is mainly the type Ⅰ mode.
In order to perfectly consider the role of crack seepage in rock slope failure, on basis of numerical manifold method program with the function of crack propagation, the coupling mechanism of seepage and deformation is illustrated and the corresponding coupling equations are deduced from the viewpoint of minimum potential energy principle. The simulation of seepage and fracture is implemented in the program. This program is used to simulate the failure of rock slope with an initial crack under seepage load. The results show that the crack begins to propagate under the initial water pressure, and gradually runs through the rockmass to form the block. Therefore, the block breaks away the original rockmass under the action of gravity. Meanwhile, from the calculation of the stress intensity factor (SIF) in the crack propagation, it can be seen that the first SIF value is always larger than the second one. With calculation time going on, the difference between them becomes larger. Hence, the crack propagation is mainly the type Ⅰ mode.
2008, 16(1): 59-62.
Blasting vibration is one of the most important factors affecting slope stability. Based on actual engineering project, this paper uses the FDM software-FLAC to simulate the effects of blasting vibration on slope stability. The problems about boundary conditions,dynamic time series,and rational damping for the geological body are discussed. Through in-depth dynamical analysis of velocity and displacement, the paper shows the vibration characteristic of the slope and its displacement and velocity varying laws. The results present in this paper can be used to guide the productive practice to ensure slope stability.
Blasting vibration is one of the most important factors affecting slope stability. Based on actual engineering project, this paper uses the FDM software-FLAC to simulate the effects of blasting vibration on slope stability. The problems about boundary conditions,dynamic time series,and rational damping for the geological body are discussed. Through in-depth dynamical analysis of velocity and displacement, the paper shows the vibration characteristic of the slope and its displacement and velocity varying laws. The results present in this paper can be used to guide the productive practice to ensure slope stability.
FIELD HORIZONTAL PUSH SHEAR TEST FOR MECHANICAL PROPERTY OF SOIL -ROCK MIXTURES UNDER CYCLIC LOADING
2008, 16(1): 63-69.
Soil-Rock mixture(S-RM) is a kind of inhomogeneous geomaterial. Taking a Yunnan highway S-RM slope as an example, horizontal push-shear tests under loading and unloading conditions were preformed to three selected samples. Then the curves of shearing strength versus displacement of these three samples were received. Studies were performed to the characteristics of these curves. Through the analysis of the samples' sliding surface under three-dimension, it seems that it is inaccurately to calculate the strength parameters of S-RM for the scrambling of the three-dimension sliding surface. Based on the three limit-equilibrium theory, the method of calculating the strength parameters of S-RM under three-dimension condition were put forward. Using this method, the strength parameters and the residual strength parameters of S-RM in the study area were received. These parameters can be very important to evaluate slopes.
Soil-Rock mixture(S-RM) is a kind of inhomogeneous geomaterial. Taking a Yunnan highway S-RM slope as an example, horizontal push-shear tests under loading and unloading conditions were preformed to three selected samples. Then the curves of shearing strength versus displacement of these three samples were received. Studies were performed to the characteristics of these curves. Through the analysis of the samples' sliding surface under three-dimension, it seems that it is inaccurately to calculate the strength parameters of S-RM for the scrambling of the three-dimension sliding surface. Based on the three limit-equilibrium theory, the method of calculating the strength parameters of S-RM under three-dimension condition were put forward. Using this method, the strength parameters and the residual strength parameters of S-RM in the study area were received. These parameters can be very important to evaluate slopes.
2008, 16(1): 70-75.
In this paper, a generalized equation of three dimensional limit equilibrium methods for slope stability analysis is developed under the four assumptions. They are: (1) The safety factor is defined as the strength reduction factor of materials; (2) The soil is looked as rigid body, and the sliding surface obeys the Mohr-Columb strength broken criterion; (3) The action position of dNz locates at the middle of the bottom of a column; (4) The angle q is the angle between the shearing force of the sliding surface and the intersection of the sliding surface and the xoz plane. This equation can give the equations associated with the general three dimensional limit equilibrium, the simplified Bishop three dimensional limit equilibrium, the simplified Janbu three dimensional limit equilibrium, or the Spencer three dimensional limit equilibrium on the basis of the confined conditions for each specific method.
In this paper, a generalized equation of three dimensional limit equilibrium methods for slope stability analysis is developed under the four assumptions. They are: (1) The safety factor is defined as the strength reduction factor of materials; (2) The soil is looked as rigid body, and the sliding surface obeys the Mohr-Columb strength broken criterion; (3) The action position of dNz locates at the middle of the bottom of a column; (4) The angle q is the angle between the shearing force of the sliding surface and the intersection of the sliding surface and the xoz plane. This equation can give the equations associated with the general three dimensional limit equilibrium, the simplified Bishop three dimensional limit equilibrium, the simplified Janbu three dimensional limit equilibrium, or the Spencer three dimensional limit equilibrium on the basis of the confined conditions for each specific method.
2008, 16(1): 76-83.
An improved immune genetic algorithm has been put forward in this paper. It is based onthe thoughts of vaccine selection, vaccination, immune memory, gene affinity mutation, gene recombination. On the basis of the algorithm, a search method for the most dangerous slip surface of soil slopes has been studied. The method is further combined with Monte-carlo stochastic simulated technique. The method has been used in the soil slope reliability analysis. An actual case study is given. The calculating result for the actual case is in accordance with the fact. The study verifies the validity of the algorithm and the correctness of the method.
An improved immune genetic algorithm has been put forward in this paper. It is based onthe thoughts of vaccine selection, vaccination, immune memory, gene affinity mutation, gene recombination. On the basis of the algorithm, a search method for the most dangerous slip surface of soil slopes has been studied. The method is further combined with Monte-carlo stochastic simulated technique. The method has been used in the soil slope reliability analysis. An actual case study is given. The calculating result for the actual case is in accordance with the fact. The study verifies the validity of the algorithm and the correctness of the method.
2008, 16(1): 84-88.
Based on the investigation and geologic exploration information of a hydroelectric power station, the authors set up a computational model which reflects project area steep topography, soft fracture, elaborate underground powerhouse, high earth stress and environmental condition as well. According to earth stress actual measurement results, the initial stress field is played back by linear-elasticity method. To simplify the numerical model, the author adopts an adding stress program and analyses the large-scale caverns in three-dimensional modeling by elastic-plasticity method. The results show clearly that the wall rock between the neighbor cavities,in especial between main power house and tail water houses, the rock wall local plastic failure and destroy region mostly at cavity waist and top angle region, while the stress concentration mostly at top angle region. Both the modeling method and analytic result have a reference sense toward analogy engineering.
Based on the investigation and geologic exploration information of a hydroelectric power station, the authors set up a computational model which reflects project area steep topography, soft fracture, elaborate underground powerhouse, high earth stress and environmental condition as well. According to earth stress actual measurement results, the initial stress field is played back by linear-elasticity method. To simplify the numerical model, the author adopts an adding stress program and analyses the large-scale caverns in three-dimensional modeling by elastic-plasticity method. The results show clearly that the wall rock between the neighbor cavities,in especial between main power house and tail water houses, the rock wall local plastic failure and destroy region mostly at cavity waist and top angle region, while the stress concentration mostly at top angle region. Both the modeling method and analytic result have a reference sense toward analogy engineering.
2008, 16(1): 89-97.
This paper presents a comprehensive experimental evaluation of rock joint shear strength. The test specimens are natural rock joints and have differential anastomotic degrees. The paper presents the tests for the JRC-JCS model and the JRC-JMS model in drying and saturated conditions. The test results show that the comprehensive evaluation of rock joint shear strength by the JRC-JCS model has a good reliability on the bases of the directional statistical measurement, the analysis of JRC scale effect, as well as the consideration of reduced JRC during shearing. The JRC-JMC model considering anastomotic degree can better predict the rock joint shear strength than the JRC-JCS model.
This paper presents a comprehensive experimental evaluation of rock joint shear strength. The test specimens are natural rock joints and have differential anastomotic degrees. The paper presents the tests for the JRC-JCS model and the JRC-JMS model in drying and saturated conditions. The test results show that the comprehensive evaluation of rock joint shear strength by the JRC-JCS model has a good reliability on the bases of the directional statistical measurement, the analysis of JRC scale effect, as well as the consideration of reduced JRC during shearing. The JRC-JMC model considering anastomotic degree can better predict the rock joint shear strength than the JRC-JCS model.
2008, 16(1): 98-103.
This paper analyses the characteristics of geology and deformation, filling at sliding zone, mechanical parameters of the fracture plan and slip surface of the fracture in the creep rock mass zone B at Longtan hydropower station in Guang-xi province. The analysis is combined with monitoring data, rock weathering, structural feature of slope and slide-tow of slope surface rock mass. The paper draws the conclusion that the cause of fracture plane and slide surface of the fracture was due to a combined effect of the slope lithologic, the erosion by water, and the different weathering characteristic of different rock masses. The analysis of monitoring data also shows that the slope deformation value was little, the deformation trend was not obviously and the slope was stable.
This paper analyses the characteristics of geology and deformation, filling at sliding zone, mechanical parameters of the fracture plan and slip surface of the fracture in the creep rock mass zone B at Longtan hydropower station in Guang-xi province. The analysis is combined with monitoring data, rock weathering, structural feature of slope and slide-tow of slope surface rock mass. The paper draws the conclusion that the cause of fracture plane and slide surface of the fracture was due to a combined effect of the slope lithologic, the erosion by water, and the different weathering characteristic of different rock masses. The analysis of monitoring data also shows that the slope deformation value was little, the deformation trend was not obviously and the slope was stable.
2008, 16(1): 104-108.
It is very difficult to calculate the disturbed thickness of slide zone in rock slopes with two-layer structure, although stability analysis of the rock slopes can be easily carried out. According to the theory of energy method, the formula of safety factor with meaning of upper bound solution is deduced in the paper. Furthermore, the formula of disturbed thickness is also derived when both the external work done by self weight of the slope and internal energy dissipation caused by slide zone are all taken into consideration. On the basis of analyzing a typical case, the paper puts forward a new concept of disturbed zonage about slide zone, and divides the disturbed thickness into five zones according to the degree of disturbance. They are the intensely, strongly, moderately , weakly and slightly disturbed zones. The depth range of reinforcing treatment for a two-layered rock slope should exceed the bottom of the slightly disturbed zone.
It is very difficult to calculate the disturbed thickness of slide zone in rock slopes with two-layer structure, although stability analysis of the rock slopes can be easily carried out. According to the theory of energy method, the formula of safety factor with meaning of upper bound solution is deduced in the paper. Furthermore, the formula of disturbed thickness is also derived when both the external work done by self weight of the slope and internal energy dissipation caused by slide zone are all taken into consideration. On the basis of analyzing a typical case, the paper puts forward a new concept of disturbed zonage about slide zone, and divides the disturbed thickness into five zones according to the degree of disturbance. They are the intensely, strongly, moderately , weakly and slightly disturbed zones. The depth range of reinforcing treatment for a two-layered rock slope should exceed the bottom of the slightly disturbed zone.
2008, 16(1): 109-115.
This paper is based on Swedish circle method and Bishop Slices Method to analyze the stability of complete slope. The X coordinates of two points where the circular failure surface intersected the slope and the Y coordinate of the centre of circular are chosen to be the optimization variables. The variables are optimized with a kind of improved decimal strings genetic algorithm (IDSGA). On the basis of simple decimal strings genetic algorithm, the IDSGA with the best chromosome clone operation, younger generation chromosomes prepotency operation and multi-generations adjusting environment operation is put forward. It is shown from calculating ACADS test problems that the algorithm has several main functions such as better adaptive ability, expediting constringency, avoiding earliness, and improving precision.
This paper is based on Swedish circle method and Bishop Slices Method to analyze the stability of complete slope. The X coordinates of two points where the circular failure surface intersected the slope and the Y coordinate of the centre of circular are chosen to be the optimization variables. The variables are optimized with a kind of improved decimal strings genetic algorithm (IDSGA). On the basis of simple decimal strings genetic algorithm, the IDSGA with the best chromosome clone operation, younger generation chromosomes prepotency operation and multi-generations adjusting environment operation is put forward. It is shown from calculating ACADS test problems that the algorithm has several main functions such as better adaptive ability, expediting constringency, avoiding earliness, and improving precision.
2008, 16(1): 116-123.
Artificial neural networks (ANNs) can be used for the ground surface movement prediction in the cases that traditional theories of subsidence and forecasting methods are not suitable, because they are based on the nonmetal mine underground mining. New methods are needed to deal with the ground surface movement problems in metal mine area such as Jinchuan Nickel mine with high dip angle. It is known that the Elman neural network can well approach any nonlinear continuous function and has ability to reflect dynamic features of the systems. Therefore, a time-series forecasting model of ground surface movement based on Elman neural network is presented. The datum of ground surface deformation got form GPS monitoring in Jinchuan Mine area were used to verify this model. Through comparing the forecasting result from the Elman model with the monitoring datum from GPS, it shows that the ANN prediction model is a useful method with good precision, especially under short time step prediction. The proposed method can offer a solution to the shortage of method in practice to a certain extent.
Artificial neural networks (ANNs) can be used for the ground surface movement prediction in the cases that traditional theories of subsidence and forecasting methods are not suitable, because they are based on the nonmetal mine underground mining. New methods are needed to deal with the ground surface movement problems in metal mine area such as Jinchuan Nickel mine with high dip angle. It is known that the Elman neural network can well approach any nonlinear continuous function and has ability to reflect dynamic features of the systems. Therefore, a time-series forecasting model of ground surface movement based on Elman neural network is presented. The datum of ground surface deformation got form GPS monitoring in Jinchuan Mine area were used to verify this model. Through comparing the forecasting result from the Elman model with the monitoring datum from GPS, it shows that the ANN prediction model is a useful method with good precision, especially under short time step prediction. The proposed method can offer a solution to the shortage of method in practice to a certain extent.
2008, 16(1): 124-129.
Expansive soil is a kind of special soils and can do huge harm to engineering project. This paper proposes a PAS chemistry treatment to expansive soil embankment. The modified principle and special construction craft of this new method is presented. The results of experimental study show that the swelling characteristics and strength parameters of modified expansive soil are changed obviously. The results indicate that PAS chemical treatment is an effective method for expansive embankment. Through the PAS treatment, the swelling and shrinking deformation can be reduced remarkably. The strength and the water stability can also be significantly improved. On the other hand, the PAS does not change the cultivate capacity of the soil. Plant fixed slope method can be adopted as ecology protection for the treated embankment slope. Comparing with long-distance replacements, specially in the area massively distributed with high plastic expansive soils, the PAS treatment has a very greatly economical superiority to be used.
Expansive soil is a kind of special soils and can do huge harm to engineering project. This paper proposes a PAS chemistry treatment to expansive soil embankment. The modified principle and special construction craft of this new method is presented. The results of experimental study show that the swelling characteristics and strength parameters of modified expansive soil are changed obviously. The results indicate that PAS chemical treatment is an effective method for expansive embankment. Through the PAS treatment, the swelling and shrinking deformation can be reduced remarkably. The strength and the water stability can also be significantly improved. On the other hand, the PAS does not change the cultivate capacity of the soil. Plant fixed slope method can be adopted as ecology protection for the treated embankment slope. Comparing with long-distance replacements, specially in the area massively distributed with high plastic expansive soils, the PAS treatment has a very greatly economical superiority to be used.
2008, 16(1): 130-134.
The fuzzy information analytic method is used in the stability analysis of landslide on expressway in Yun-Nan province. This paper applies the fuzzy information analytic method such as information distribution and information concentration to the 50 sets of data of landslides. These landslides are located on the Yuanjiang-Mohei expressway in Yunnan Province. The fuzzy relationships are developed for the landslide stability with respect to the height, angle of slope, cohesion, and internal friction angle of landslide. These parameters are the important influence factors. The corresponding model of landslide stability analysis is established. The developed model is verified with other landslide in the area. It is indicated that the model has low error and good effect.
The fuzzy information analytic method is used in the stability analysis of landslide on expressway in Yun-Nan province. This paper applies the fuzzy information analytic method such as information distribution and information concentration to the 50 sets of data of landslides. These landslides are located on the Yuanjiang-Mohei expressway in Yunnan Province. The fuzzy relationships are developed for the landslide stability with respect to the height, angle of slope, cohesion, and internal friction angle of landslide. These parameters are the important influence factors. The corresponding model of landslide stability analysis is established. The developed model is verified with other landslide in the area. It is indicated that the model has low error and good effect.
REVIEW ON FIBER OPTIC SENSOR-BASED MONITORING TECHNIQUES FOR GEOLOGICAL AND GEOTECHNICAL ENGINEERING
2008, 16(1): 135-143.
In comparison with the conventional sensors, fiber optic sensor offers a number of attractive features and has become one of the popular research subjects in the field of geology and geotechnical engineering monitoring. This paper introduces the classification, basic measuring principle and current research achievements and development status of fiber optic sensing system in China and overseas. A comprehensive comparison of their performance and characteristic is made. Some relevant research topics in the application of fiber optic sensor-based monitoring technique to geology and geotechnical engineering are also put forward.
In comparison with the conventional sensors, fiber optic sensor offers a number of attractive features and has become one of the popular research subjects in the field of geology and geotechnical engineering monitoring. This paper introduces the classification, basic measuring principle and current research achievements and development status of fiber optic sensing system in China and overseas. A comprehensive comparison of their performance and characteristic is made. Some relevant research topics in the application of fiber optic sensor-based monitoring technique to geology and geotechnical engineering are also put forward.
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