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Editor Work2006 Vol. 14, No. 1
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Abstract
Most of dynamic processes occurred in geo-sphere under interaction between lithosphere and hydrosphere,atmosphere and biosphere,can be described as multiple connective processes.Its activity involves the integration and evolution of the thermal,fluidal,solid,chemical and biological movements,which follow the universal basic low of material movement.The interaction between them may cause energy transition and parameter variation in the geo-sphere process.To make a systematic and synthetic evaluation and prediction of geo-sphere dynamic process,a definition of multiple connective THMCB processes is to be established,and a connectivity analysis approach is to be used,as suggested in this paper.A numerical methodology and relevant experimental studies are also presented and discussed.
Most of dynamic processes occurred in geo-sphere under interaction between lithosphere and hydrosphere,atmosphere and biosphere,can be described as multiple connective processes.Its activity involves the integration and evolution of the thermal,fluidal,solid,chemical and biological movements,which follow the universal basic low of material movement.The interaction between them may cause energy transition and parameter variation in the geo-sphere process.To make a systematic and synthetic evaluation and prediction of geo-sphere dynamic process,a definition of multiple connective THMCB processes is to be established,and a connectivity analysis approach is to be used,as suggested in this paper.A numerical methodology and relevant experimental studies are also presented and discussed.
2006, 14(1): 5-12.
The active tectonics is closely related to environmental disaster.The geological disaster can be directly provoked by active tectonics, while earthquakes generated by activity of constitutions may derive a series of geological disasters.In addition,inappropriate activities of mankind can deteriorate the geological tectonic environment and aggravate the geological disasters.As for the study on the relations between active tectonics and the environmental disaster,the following four scientific problems should be addressed immediately: the zoning evaluation on the stability of China regional crust based on the modern continental dynamics;the uplift of Qinghai-Xizang Plateau and geological disasters;the engineering hazard of active tectonics and its prevention;and genetic mechanics of geological disasters by coupling the inherent and external dynamics.
The active tectonics is closely related to environmental disaster.The geological disaster can be directly provoked by active tectonics, while earthquakes generated by activity of constitutions may derive a series of geological disasters.In addition,inappropriate activities of mankind can deteriorate the geological tectonic environment and aggravate the geological disasters.As for the study on the relations between active tectonics and the environmental disaster,the following four scientific problems should be addressed immediately: the zoning evaluation on the stability of China regional crust based on the modern continental dynamics;the uplift of Qinghai-Xizang Plateau and geological disasters;the engineering hazard of active tectonics and its prevention;and genetic mechanics of geological disasters by coupling the inherent and external dynamics.
2006, 14(1): 13-17.
A fault lies across in a hydropower reservoir region only 3 km upstream of Majiahe dam on the Jinsha River Its structure patterns and deformation features vary greatly between different classes of fracture surfaces and even different parts of the primary fracture surfaces.Therefore,characterization of the fault is the key to stability assessment of the dam as well,which has been a hot topic for debating.Based on new data collected by large-scale geological mapping,surveying adits and structure analysis,the authors conclude that that fault is a small thrust in the interior area of a plateform.It is the first time that the geometry and kinematics features as well as influence region are determined.The dynamics of the fault formation is also analyzed.The research results provide information needed for construction and safe operation of the dam.
A fault lies across in a hydropower reservoir region only 3 km upstream of Majiahe dam on the Jinsha River Its structure patterns and deformation features vary greatly between different classes of fracture surfaces and even different parts of the primary fracture surfaces.Therefore,characterization of the fault is the key to stability assessment of the dam as well,which has been a hot topic for debating.Based on new data collected by large-scale geological mapping,surveying adits and structure analysis,the authors conclude that that fault is a small thrust in the interior area of a plateform.It is the first time that the geometry and kinematics features as well as influence region are determined.The dynamics of the fault formation is also analyzed.The research results provide information needed for construction and safe operation of the dam.
2006, 14(1): 18-22.
This paper focuses on contributing ratios of the slope shape towards the landslide development.The slope shape data of landslides from the Yunyang to Wushan segment of the Three Gorges Reservoir area is analyzed with GIS information statistical methodologies.Five slope shape models were obtained.The contributing ratio is computed by dividing the contributing index of slope shape with the total contributing index of slope shape.It was concluded that the model IV contributes most to landslide development;models III and V contribute moderately;and models I II contribute little to landslide development.
This paper focuses on contributing ratios of the slope shape towards the landslide development.The slope shape data of landslides from the Yunyang to Wushan segment of the Three Gorges Reservoir area is analyzed with GIS information statistical methodologies.Five slope shape models were obtained.The contributing ratio is computed by dividing the contributing index of slope shape with the total contributing index of slope shape.It was concluded that the model IV contributes most to landslide development;models III and V contribute moderately;and models I II contribute little to landslide development.
2006, 14(1): 23-27.
Through analysis of engineering geology conditions of the landslide and its development in the south of Science and Technology Center at Southwest University of Science and Technology,the authors gained a a better understanding of its mechanism.The results obtained from the computation using the partition transfer coefficient indicate that the landslide is currently in unstable or temporarily stable condition.In order to ensure the safety of the road and the proposed Science and Technology Center,the authors recommend a comprehensive control program,which combines glide-resisting stake and earth-retaining walls.
Through analysis of engineering geology conditions of the landslide and its development in the south of Science and Technology Center at Southwest University of Science and Technology,the authors gained a a better understanding of its mechanism.The results obtained from the computation using the partition transfer coefficient indicate that the landslide is currently in unstable or temporarily stable condition.In order to ensure the safety of the road and the proposed Science and Technology Center,the authors recommend a comprehensive control program,which combines glide-resisting stake and earth-retaining walls.
2006, 14(1): 28-34.
Quasi-soft soil is one special kind of soft clay with different characteristics in its formation,distribution,physical composition from other common sediments.Therefore,landslide occurred in the quasi-soft soil should have its own characteristics.The strata lithology,geologic structure and hydrogeologic features of the landslide are demonstrated by a case study at the K108 quasi-soft soil landslide along the Beijing-Zhuhai highway.Five slip surfaces and shape of slip bed of the landslide are identified by displacement monitoring.It was concluded that rainfall and slope excavation are two primary causes for landslide.
Quasi-soft soil is one special kind of soft clay with different characteristics in its formation,distribution,physical composition from other common sediments.Therefore,landslide occurred in the quasi-soft soil should have its own characteristics.The strata lithology,geologic structure and hydrogeologic features of the landslide are demonstrated by a case study at the K108 quasi-soft soil landslide along the Beijing-Zhuhai highway.Five slip surfaces and shape of slip bed of the landslide are identified by displacement monitoring.It was concluded that rainfall and slope excavation are two primary causes for landslide.
2006, 14(1): 35-40.
The soft rock widely distributed in the engineering slope can be classified into four kinds: argillized seams,coal,carbonaceous shale, and pelitic siltstone.Its origination,spatial distribution and orientation,as well as slaking characteristics directly affect the stability of the slope and design of anchoring and other supports.A careful study of the slaking characteristics of several kinds of soft rock formations in soft zones such as faults F3,L9,L10,Lc,L11 etc.,uncover that the soft rock highly absorbs water,which facilitates argillization,softening,and slaking.A circulated slaking experiment shows that the degree of slaking is highly related to the ratio of clay in the soft rock and times of the slaking.According to the degree of the slaking and shape of the slaking substance,the slaking process can be divided into five types of slaking rock and 5 kinds of failure patterns.The paper further discusses the slaking mechanisms.
The soft rock widely distributed in the engineering slope can be classified into four kinds: argillized seams,coal,carbonaceous shale, and pelitic siltstone.Its origination,spatial distribution and orientation,as well as slaking characteristics directly affect the stability of the slope and design of anchoring and other supports.A careful study of the slaking characteristics of several kinds of soft rock formations in soft zones such as faults F3,L9,L10,Lc,L11 etc.,uncover that the soft rock highly absorbs water,which facilitates argillization,softening,and slaking.A circulated slaking experiment shows that the degree of slaking is highly related to the ratio of clay in the soft rock and times of the slaking.According to the degree of the slaking and shape of the slaking substance,the slaking process can be divided into five types of slaking rock and 5 kinds of failure patterns.The paper further discusses the slaking mechanisms.
2006, 14(1): 41-44.
A gypsum layer of 2 meters thickness lies beneath the riverbed at a hydropower plant on the upstream of the Yellow River.Gypsum is easy to collapse when encountering water.It is the least favorable rockmass for construction of the hydropower plant because of its weak engineering geological properties and low mechanical strength.This paper assesses impacts of dissolution of the gypsum layer on the stability of dam base and provides guidelines for minimizing or preventing such impacts.
A gypsum layer of 2 meters thickness lies beneath the riverbed at a hydropower plant on the upstream of the Yellow River.Gypsum is easy to collapse when encountering water.It is the least favorable rockmass for construction of the hydropower plant because of its weak engineering geological properties and low mechanical strength.This paper assesses impacts of dissolution of the gypsum layer on the stability of dam base and provides guidelines for minimizing or preventing such impacts.
2006, 14(1): 45-51.
Dynamic consolidation with drainage was a new technique for treatment of soft soil foundation developed by integrating some drainage systems with the traditional compacting technique.This paper first presents research needs and fundamental mechanics of this technique by reviewing recent case studies around world and associated difficulties in those studies.At the end of the paper,the author recommends several research topics related to the mechanism of dynamic consolidation with drainage.
Dynamic consolidation with drainage was a new technique for treatment of soft soil foundation developed by integrating some drainage systems with the traditional compacting technique.This paper first presents research needs and fundamental mechanics of this technique by reviewing recent case studies around world and associated difficulties in those studies.At the end of the paper,the author recommends several research topics related to the mechanism of dynamic consolidation with drainage.
2006, 14(1): 52-59.
The primary sediment in the Yellow River delta is silt. It is not clear how the permeable and impermeable interlayers impact on the accumulation of the pore water pressure?dissipation and liquefaction of sediments under the cyclic loading.This paper presents results of in-situ vibration test and lab tests for four kinds of interlayers.The results show that physical and mechanical properties of the silt,such as the pore water pressure,grain size composition,density,water contents etc.vary with the type of interlayer?A permeable layer improves its resistance against liquefaction,while an impermeable interlayer is opposite.
The primary sediment in the Yellow River delta is silt. It is not clear how the permeable and impermeable interlayers impact on the accumulation of the pore water pressure?dissipation and liquefaction of sediments under the cyclic loading.This paper presents results of in-situ vibration test and lab tests for four kinds of interlayers.The results show that physical and mechanical properties of the silt,such as the pore water pressure,grain size composition,density,water contents etc.vary with the type of interlayer?A permeable layer improves its resistance against liquefaction,while an impermeable interlayer is opposite.
2006, 14(1): 60-64.
Residual soil is one of special soils,of which engineering geological property is usually different because of its difference in origin of rock,geological environment and weathering condition.With field exploration,laboratory tests and in-situ tests,the physical and mechanical properties of the residual diorite in Jinan were studied thoroughly.The stratigraphic section of the soil can be classified as two layers on the perpendicular direction.Considering inhomogeneity of the residual soil mass and wide divergence of the value of mechanical properties,the authors suggest values of c,,a,Es,fak as a guideline for engineering practice.It was also pointed out that the interlayer and inhomogeneity of the weathering layers should be emphasized in design and construction when the residual diorite or one of the geologic layers is used for foundation of a structure.
Residual soil is one of special soils,of which engineering geological property is usually different because of its difference in origin of rock,geological environment and weathering condition.With field exploration,laboratory tests and in-situ tests,the physical and mechanical properties of the residual diorite in Jinan were studied thoroughly.The stratigraphic section of the soil can be classified as two layers on the perpendicular direction.Considering inhomogeneity of the residual soil mass and wide divergence of the value of mechanical properties,the authors suggest values of c,,a,Es,fak as a guideline for engineering practice.It was also pointed out that the interlayer and inhomogeneity of the weathering layers should be emphasized in design and construction when the residual diorite or one of the geologic layers is used for foundation of a structure.
2006, 14(1): 65-67.
Based on the analysis of the water levels of hot water wells and seismic activities in Xi'an and its neighboring area,the authors concluded that the geothermal water exploitation in Xi'an is closely related to the seismic activities in Xi'an and its neighboring area.The seismic activities have been intensified by geothermal water exploitation so that earthquake epicenters migrate from the urban area of Xi'an to its adjacent areas.
Based on the analysis of the water levels of hot water wells and seismic activities in Xi'an and its neighboring area,the authors concluded that the geothermal water exploitation in Xi'an is closely related to the seismic activities in Xi'an and its neighboring area.The seismic activities have been intensified by geothermal water exploitation so that earthquake epicenters migrate from the urban area of Xi'an to its adjacent areas.
2006, 14(1): 68-71.
The water intrusion is a common problem in tunnels,especially in southern karst area.It affects the whole process of tunnel construction and operation.According to the survey data,1525-meter long(62% of total length of Zoumaling tunnel) karst sector(including fault fracture zone) is prone to water intrusion.This paper presented a preliminary prediction of water discharge,which may be caused by continued tunnel excavation,based on real-time discharge monitoring data of excavated tunnel and project surveys.The results provide guidelines for control of potential water intrusion.
The water intrusion is a common problem in tunnels,especially in southern karst area.It affects the whole process of tunnel construction and operation.According to the survey data,1525-meter long(62% of total length of Zoumaling tunnel) karst sector(including fault fracture zone) is prone to water intrusion.This paper presented a preliminary prediction of water discharge,which may be caused by continued tunnel excavation,based on real-time discharge monitoring data of excavated tunnel and project surveys.The results provide guidelines for control of potential water intrusion.
Multi-layer loose and thick Quaternary sediments in the Yangtzi River delta create a complex aquifer system.Partial pumping wells used in dewatering project and the diaphragm wall not attached to the bottom of layer around pits result in a very complex characteristic of three-dimensional groundwater seepage in the foundation pit.In this paper authors use the dewatering of the foundation pit at Shanghai Finance Center as a case study to demonstrate how the three-dimensional finite-difference numerical method can be used to characterize the groundwater seepage in the foundation pit.It is a multi-layer aquifer system with a confining layer at a depth of 149 m,a pits diaphragm wall at a depth of 34 m and an anticipated water level drop of 26 m within the pit.An optimized method for dewatering of the foundation pit is eventually derived.
Multi-layer loose and thick Quaternary sediments in the Yangtzi River delta create a complex aquifer system.Partial pumping wells used in dewatering project and the diaphragm wall not attached to the bottom of layer around pits result in a very complex characteristic of three-dimensional groundwater seepage in the foundation pit.In this paper authors use the dewatering of the foundation pit at Shanghai Finance Center as a case study to demonstrate how the three-dimensional finite-difference numerical method can be used to characterize the groundwater seepage in the foundation pit.It is a multi-layer aquifer system with a confining layer at a depth of 149 m,a pits diaphragm wall at a depth of 34 m and an anticipated water level drop of 26 m within the pit.An optimized method for dewatering of the foundation pit is eventually derived.
2006, 14(1): 83-89.
Rock burst is a type of instability of hard intact surrounding rock in the condition of high field stress.The relations between rock burst intensity and surrounding rock rating are not known clearly.It is very important to find the relations between rock burst and surrounding rock classification in the high field stress.In this paper,some problems such as the relations between rock burst intensity and surrounding rock rating,the choice of the criteria of rock burst for water resources and hydroelectric underground excavation in China are discussed.An example for surrounding rock mass classification of a deep-buried tunnel in China is given.A suggestion that the relations between rock burst intensity and surrounding rock rating should be increased in national correlation criterion is proposed.
Rock burst is a type of instability of hard intact surrounding rock in the condition of high field stress.The relations between rock burst intensity and surrounding rock rating are not known clearly.It is very important to find the relations between rock burst and surrounding rock classification in the high field stress.In this paper,some problems such as the relations between rock burst intensity and surrounding rock rating,the choice of the criteria of rock burst for water resources and hydroelectric underground excavation in China are discussed.An example for surrounding rock mass classification of a deep-buried tunnel in China is given.A suggestion that the relations between rock burst intensity and surrounding rock rating should be increased in national correlation criterion is proposed.
2006, 14(1): 96-100.
The survey and assessment were conducted at an area where a long tunnel was planned to construct.The work aimed at gaining radioactive geology information needed for the selection of the tunnel site and feasibility study.Radioactivity was measured in-situ over 392 rock and soil samples.A total of 111 groups of rock and soil samples and 5 groups of water samples were collected for radioactive nuclide analysis(Ra,Tu and ~(40)K).The results show that specific activity of ~(226)Ra is anomalously higher at the connective belts of coal seams and sandstone of Jurassic age at a coal mine and their internal and external exposure indices exceed the national standard.The enrichment of ~(226)Ra may be resulted from the organismal adsorption/desorption of radioactive nuclides at the coal seams.Therefore,it is recommended that tunnel should be rerouted to avoid those sites,and the environmental terrestrial radiation and radon emanation should be monitored during the tunnel's construction.
The survey and assessment were conducted at an area where a long tunnel was planned to construct.The work aimed at gaining radioactive geology information needed for the selection of the tunnel site and feasibility study.Radioactivity was measured in-situ over 392 rock and soil samples.A total of 111 groups of rock and soil samples and 5 groups of water samples were collected for radioactive nuclide analysis(Ra,Tu and ~(40)K).The results show that specific activity of ~(226)Ra is anomalously higher at the connective belts of coal seams and sandstone of Jurassic age at a coal mine and their internal and external exposure indices exceed the national standard.The enrichment of ~(226)Ra may be resulted from the organismal adsorption/desorption of radioactive nuclides at the coal seams.Therefore,it is recommended that tunnel should be rerouted to avoid those sites,and the environmental terrestrial radiation and radon emanation should be monitored during the tunnel's construction.
2006, 14(1): 101-106.
At present,the level of mechanization and automation of tunnel boring machines(TBM) has been improved significantly,and TBMs can be designed to excavate tunnels with different shapes under different geological conditions.The types of TBMs are becoming more versatile.In order to facilitate selection of TBMs in a project based on engineering geology and hydrogeology conditions,project characteristics and environmental constraints,it is necessary to understand the operation mechanisms of different TBMs and classify them accordingly.In this paper,the authors describe the operation mechanisms of each type of full-face TBM,and classify full-face TBMs by their final excavated tunnel section,immediate support mechanism and cutting mechanism.Based on applicability of each type of TBM,users can select appropriate TBMs to meet their needs and geological conditions.
At present,the level of mechanization and automation of tunnel boring machines(TBM) has been improved significantly,and TBMs can be designed to excavate tunnels with different shapes under different geological conditions.The types of TBMs are becoming more versatile.In order to facilitate selection of TBMs in a project based on engineering geology and hydrogeology conditions,project characteristics and environmental constraints,it is necessary to understand the operation mechanisms of different TBMs and classify them accordingly.In this paper,the authors describe the operation mechanisms of each type of full-face TBM,and classify full-face TBMs by their final excavated tunnel section,immediate support mechanism and cutting mechanism.Based on applicability of each type of TBM,users can select appropriate TBMs to meet their needs and geological conditions.
2006, 14(1): 107-110.
DJM is a soil improvement technology which pneumatically delivers powdered reagent into ground and mixes it with soils to form a soil-reagent column.It is an efficient method for reinforcement of a soft foundation.Bearing capacity of the dry jet mixed piles is an important parameter for the composite foundation,which is difficulty to determine because of the complexity between the pile and soil.In this paper authors compare different methods,and suggest guidelines for using different methods in determination of bearing capacity.
DJM is a soil improvement technology which pneumatically delivers powdered reagent into ground and mixes it with soils to form a soil-reagent column.It is an efficient method for reinforcement of a soft foundation.Bearing capacity of the dry jet mixed piles is an important parameter for the composite foundation,which is difficulty to determine because of the complexity between the pile and soil.In this paper authors compare different methods,and suggest guidelines for using different methods in determination of bearing capacity.
2006, 14(1): 111-116.
Few studies have been conducted on the mechanism and behavior of soil arching surrounding passive piles.In this paper a plane FEM is applied to assess four key factors of soil arching,such as its shape,the vertical displacement contour,plastic or tensile area of soil surrounding piles and residual stress post piling.Changes in cohesion,internal friction angle,elastic modulus,Poisson ratio,dilatancy angle,and interface conditions are evaluated respectively.The results indicate that the yield mechanisms of cohesive and non-cohesive soils around piles are different when forming the soil arching.Poisson ratio,dilatancy angle,and interface conditions play very important roles in soil arching effects.The results also demonstrate effects of interaction of pile and lateral soil movements,relationship between bypassed earth pressure around piles and soil parameters,and the discrepancy of Tomio Itos earth pressure formula.
Few studies have been conducted on the mechanism and behavior of soil arching surrounding passive piles.In this paper a plane FEM is applied to assess four key factors of soil arching,such as its shape,the vertical displacement contour,plastic or tensile area of soil surrounding piles and residual stress post piling.Changes in cohesion,internal friction angle,elastic modulus,Poisson ratio,dilatancy angle,and interface conditions are evaluated respectively.The results indicate that the yield mechanisms of cohesive and non-cohesive soils around piles are different when forming the soil arching.Poisson ratio,dilatancy angle,and interface conditions play very important roles in soil arching effects.The results also demonstrate effects of interaction of pile and lateral soil movements,relationship between bypassed earth pressure around piles and soil parameters,and the discrepancy of Tomio Itos earth pressure formula.
2006, 14(1): 117-121.
Traditional disposal of the high water content slime from the beneficiating and washing of the bauxite mine takes a long time to consolidate and causes environment contamination.Experimental results presented in this paper show that compound curing agent made up of 72% cement,20% gypsum,5% lime and 3% sodium sulfate or made up of 72% lime,20% gypsum,5% flyash and 3% sodium sulfate could improve solidification intensity and durability if they were used at a ratio of 1:10(curing agent : slime).Its low cost and environment-friendly merits create a great potential for future application.
Traditional disposal of the high water content slime from the beneficiating and washing of the bauxite mine takes a long time to consolidate and causes environment contamination.Experimental results presented in this paper show that compound curing agent made up of 72% cement,20% gypsum,5% lime and 3% sodium sulfate or made up of 72% lime,20% gypsum,5% flyash and 3% sodium sulfate could improve solidification intensity and durability if they were used at a ratio of 1:10(curing agent : slime).Its low cost and environment-friendly merits create a great potential for future application.
2006, 14(1): 122-126.
The drain and dry jet mixing column method is a new method for soft soil improvement.This method was used to treat the soft soil encountered in the Huaiyan highway.The results after the treatment show that this new method is effective.However,the change in properties of surrounding soils was not well understood.In this project,a number of field testing method including CPT and vane shear tests were used to evaluate the strength changes due to the installations of cement-mixed columns.The field test results have shown that the strength of the soft soils surrounding the piles reduced at the initial stage and then increased with the elapsed time.
The drain and dry jet mixing column method is a new method for soft soil improvement.This method was used to treat the soft soil encountered in the Huaiyan highway.The results after the treatment show that this new method is effective.However,the change in properties of surrounding soils was not well understood.In this project,a number of field testing method including CPT and vane shear tests were used to evaluate the strength changes due to the installations of cement-mixed columns.The field test results have shown that the strength of the soft soils surrounding the piles reduced at the initial stage and then increased with the elapsed time.
2006, 14(1): 127-130.
The support for porous and broken wall rock has been a major technical challenge in construction of highway tunnels.By combining geological engineering conditions and parameters of the cross section layout of Sanlichong highway tunnel,the authors simulated two cased using FLAC: support with Steel Fiber Reinforced Concrete(SFRC) and support with Polypropylene Fiber Reinforced Concrete(PFRC).The stability of the highway tunnel was analyzed for the stresses,displacements and plastic zones.The numerical simulation show that the PFRC structure could work well utilizing the utmost self-bearing capacity of the rock mass and effectively reduce thickness of the 2~(nd) support.
The support for porous and broken wall rock has been a major technical challenge in construction of highway tunnels.By combining geological engineering conditions and parameters of the cross section layout of Sanlichong highway tunnel,the authors simulated two cased using FLAC: support with Steel Fiber Reinforced Concrete(SFRC) and support with Polypropylene Fiber Reinforced Concrete(PFRC).The stability of the highway tunnel was analyzed for the stresses,displacements and plastic zones.The numerical simulation show that the PFRC structure could work well utilizing the utmost self-bearing capacity of the rock mass and effectively reduce thickness of the 2~(nd) support.
2006, 14(1): 131-137.
Geogirds,a new type of geosynthetics,are used to reduce settlement and lateral displacement of embankment because of their high strength and low elongation.In this paper,a general-purpose non-linear finite element program,ABAQUS,was used to evaluate vertical displacement at the bottom of embankment,horizontal displacements at the embankment toe at depth and ground surface.In the analysis Drucker-Prager model and Clay plasticity model were used to characterize the non-linearity of soil,while one-dimension truss element was used to represent the geogrid.Sensitivity analysis were conducted for factors such as the layer-number of reinforcements,the modulus of geogrids,the modulus of soft clay foundation,the thickness of soft clay foundation and embankment height.The results showed that geogrid reinforcement greatly reduced lateral displacement,but it has less effect on the vertical displacements.Reinforcement can also.improve the embankment stability.The analysis results matched well with observed displacement data.
Geogirds,a new type of geosynthetics,are used to reduce settlement and lateral displacement of embankment because of their high strength and low elongation.In this paper,a general-purpose non-linear finite element program,ABAQUS,was used to evaluate vertical displacement at the bottom of embankment,horizontal displacements at the embankment toe at depth and ground surface.In the analysis Drucker-Prager model and Clay plasticity model were used to characterize the non-linearity of soil,while one-dimension truss element was used to represent the geogrid.Sensitivity analysis were conducted for factors such as the layer-number of reinforcements,the modulus of geogrids,the modulus of soft clay foundation,the thickness of soft clay foundation and embankment height.The results showed that geogrid reinforcement greatly reduced lateral displacement,but it has less effect on the vertical displacements.Reinforcement can also.improve the embankment stability.The analysis results matched well with observed displacement data.
2006, 14(1): 138-142.
Slipping,turnover,dehiscence etc.are primary failure modes of retaining walls.Usually,only one or single stage retaining wall failure was considered.This paper presents a failure by groundwater piping through overlapping compound retaining walls besides those damages mentioned above at a power generation plant in the south of Dongguan city.Authors analyze quantitatively and qualitatively the instability of retaining walls and recommend appropriate measures for treatment of failure of retaining walls.
Slipping,turnover,dehiscence etc.are primary failure modes of retaining walls.Usually,only one or single stage retaining wall failure was considered.This paper presents a failure by groundwater piping through overlapping compound retaining walls besides those damages mentioned above at a power generation plant in the south of Dongguan city.Authors analyze quantitatively and qualitatively the instability of retaining walls and recommend appropriate measures for treatment of failure of retaining walls.
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