Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,t...Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.展开更多
An analytical method for determining the stresses and deformations of landfills contained by retaining walls is proposed in this paper.In the proposedmethod,the sliding resisting normal and tangential stresses of the ...An analytical method for determining the stresses and deformations of landfills contained by retaining walls is proposed in this paper.In the proposedmethod,the sliding resisting normal and tangential stresses of the retaining wall and the stress field of the sliding body are obtained considering the differential stress equilibrium equations,boundary conditions,and macroscopic forces and moments applied to the system,assuming continuous stresses at the interface between the sliding body and the retaining wall.The solutions to determine stresses and deformations of landfills contained by retaining walls are obtained using the Duncan-Chang and Hooke constitutive models.A case study of a landfill in the Hubei Province in China is used to validate the proposed method.The theoretical stress results for a slope with a retaining wall are compared with FEMresults,and the proposed theoreticalmethod is found appropriate for calculating the stress field of a slope with a retaining wall.展开更多
Soils are not necessarily uniform and may present linearly varied or layered characteristics,for example the backfilled soils behind rigid retaining walls.In the presence of large lateral thrust imposed by arch bridge...Soils are not necessarily uniform and may present linearly varied or layered characteristics,for example the backfilled soils behind rigid retaining walls.In the presence of large lateral thrust imposed by arch bridge,passive soil failure is possible.A reliable prediction of passive earth pressure for the design of such wall is challenging in complicated soil strata,when adopting the conventional limit analysis method.In order to overcome the challenge for generating a kinematically admissible velocity field and a statically allowable stress field,finite element method is incorporated into limit analysis,forming finiteelement upper-bound(FEUB)and finite-element lower-bound(FELB)methods.Pseudo-static,original and modified pseudo-dynamic approaches are adopted to represent seismic acceleration inputs.After generating feasible velocity and stress fields within discretized elements based on specific criteria,FEUB and FELB formulations of seismic passive earth pressure(coefficient K_(P))can be derived from work rate balance equation and stress equilibrium.Resorting to an interior point algorithm,optimal upper and lower bound solutions are obtained.The proposed FEUB and FELB procedures are well validated by limit equilibrium as well as lower-bound and kinematic analyses.Parametric studies are carried out to investigate the effects of influential factors on seismic K_(P).Notably,true solution of K_(P) is well estimated based on less than 5%difference between FEUB and FELB solutions under such complex scenarios.展开更多
Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause.However,barrier structures constructed along the path of a rock avalanche can partia...Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause.However,barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic events.We selected a rock avalanche in Nayong County,Guizhou Province,China as a case to study the effect of the location and height of a retaining wall on the dynamic characteristics of rock avalanche by using both actual terrain-based laboratory-model tests and coupled PFC3D-FLAC3D numerical simulations.Our findings demonstrate that a retaining wall can largely block a rock avalanche and its protective efficacy is significantly influenced by the integrity of the retaining wall.Coupled numerical simulation can serve as a powerful tool for analyzing the interaction between a rock avalanche and a retaining wall,facilitating precise observations of its deformation and destruction.The impact-curve characteristics of the retaining wall depend upon whether or not the rock avalanche-induced destruction is taken into account.The location of the retaining wall exerts a greater influence on the outcome compared to the height and materials of the retaining wall,while implementing a stepped retaining-wall pattern in accordance with the terrain demonstrates optimal efficacy in controlling rock avalanche.展开更多
In order to reduce the errors of the reliability of the retaining wall structure in the establishment of function, in the estimation of parameter and algorithm, firstly, two new reliability and stability models of ant...In order to reduce the errors of the reliability of the retaining wall structure in the establishment of function, in the estimation of parameter and algorithm, firstly, two new reliability and stability models of anti-slipping and anti-overturning based on the upper-bound theory of limit analysis were established, and two kinds of failure modes were regarded as a series of systems with multiple correlated failure modes. Then, statistical characteristics of parameters of the retaining wall structure were inferred by maximal entropy principle. At last, the structural reliabilities of single failure mode and multiple failure modes were calculated by Monte Carlo method in MATLAB and the results were compared and analyzed on the sensitivity. It indicates that this method, with a high precision, is not only easy to program and quick in calculation, but also without the limit of nonlinear functions and non-normal random variables. And the results calculated by this method which applies both the limit analysis theory, maximal entropy principle and Monte Carlo method into analyzing the reliability of the retaining wall structures is more scientific, accurate and reliable, in comparison with those calculated by traditional method.展开更多
This study investigated the influence factors on the seismic response and deformation modes of retaining walls using large-scale model shaking table tests. Experimental results showed that the distribution of peak sei...This study investigated the influence factors on the seismic response and deformation modes of retaining walls using large-scale model shaking table tests. Experimental results showed that the distribution of peak seismic earth pressures along the height of a wall was a single peak value curve. The seismic earth pressures on a gravel soil retaining wall were larger than the pressures on the weathered granite and quartz retaining walls. Also, the peak seismic earth pressure increased with increases in the peak ground acceleration and the wall height. The measured seismic active earth pressures on a rock foundation retaining wall were larger than the calculated values, and the action position of resultant seismic pressure was higher than 0.33 H. In the soil foundation retaining wall, the measured seismic earth pressures were much smaller than the calculated values, while the action position was slightly higher than 0.33 H. The soil foundation retaining wall suffered base sliding and overturning under earthquake conditions, while overturning was the main failure mode for the rock foundation retaining walls.展开更多
Dynamic earth pressure induced by machine foundations on a neighboring retaining wall is analyzed with emphasis on factors which control the intensity and location of the design forces. The meshless local Petrov-Galer...Dynamic earth pressure induced by machine foundations on a neighboring retaining wall is analyzed with emphasis on factors which control the intensity and location of the design forces. The meshless local Petrov-Galerkin (MLPG) method is used to analyze the problem for a variety of retaining wall and machine foundation geometries. The soil medium is assumed to be homogeneous and visco-elastic. The machine foundation is idealized as a harmonic sinusoidal dynamic force often encountered in practice. A number of analyses have been made to reveal the effect of the loading frequency, the location and size of the foundation and the soil shear wave velocity on the distribution and magnitude of the dynamic earth pressure. Results indicate that there is a critical frequency and a critical location for which the passive pressure takes the maxima in the entire duration of the dynamic load.展开更多
Hong Kong has a long history of applying masonry retaining walls to provide horizontal platforms and stabilize man-made slopes.Due to the sub-tropical climate,some masonry retaining walls are colonized by trees.Extrem...Hong Kong has a long history of applying masonry retaining walls to provide horizontal platforms and stabilize man-made slopes.Due to the sub-tropical climate,some masonry retaining walls are colonized by trees.Extreme weather,such as typhoons and heavy rains,may cause rupture or root failure of those trees,thus resulting in instability of the retaining walls.A monitoring and warning system for the movement of masonry retaining walls and sway of trees has been designed with the application of fiber Bragg grating(FBG)sensing technology.The monitoring system is also equipped with a solar power system and 4G data transmission devices.The key functions of the proposed monitoring system include remote sensing and data access,early warning,and real-time data visualization.The setups and working principles of the monitoring systems and related transducers are introduced.The feasibility,accuracy,serviceability and reliability of this monitoring system have been checked by in-site calibration tests and four-month monitoring.Besides,a two-level interface has been developed for data visualization.The monitoring results show that the monitored masonry retaining wall had a reversible movement up to 2.5 mm during the monitoring period.Besides,it is found that the locations of the maximum strain on trees depend on the crown spread of trees.展开更多
In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wallmodels retaining composite backfill made of a deformable geofoam inclusion and granular cohesionlessmaterial were ...In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wallmodels retaining composite backfill made of a deformable geofoam inclusion and granular cohesionlessmaterial were presented. Two different polystyrene materials were utilized as deformable inclusions.Lateral dynamic earth pressures and wall displacements at different elevations of the retaining wallmodel were monitored during the tests. The earth pressures and displacements of the retaining wallswith deformable inclusions were compared with those of the models without geofoam inclusions.Comparisons indicated that geofoam panels of low stiffness installed against the retaining wall modelaffect displacement and dynamic lateral pressure profile along the wall height. Depending on the inclusioncharacteristics and the wall flexibility, up to 50% reduction in dynamic earth pressures wasobserved. The efficiency of load and displacement reduction decreased as the flexibility ratio of the wallmodel increased. On the other hand, dynamic load reduction efficiency of the deformable inclusionincreased as the amplitude and frequency ratio of the seismic excitation increased. Relative flexibility ofthe deformable layer (the thickness and the elastic stiffness of the polystyrene material) played animportant role in the amount of load reduction. Dynamic earth pressure coefficients were compared withthose calculated with an analytical approach. Pressure coefficients calculated with this method werefound to be in good agreement with the results of the tests performed on the wall model having lowflexibility ratio. It was observed that deformable inclusions reduce residual wall stresses observed at theend of seismic excitation thus contributing to the post-earthquake stability of the retaining wall. Thegraphs presented within this paper regarding the dynamic earth pressure coefficients versus the wallflexibility and inclusion characteristics may serve for the seismic design of full-scale retaining walls withdeformable polystyrene inclusions. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
Stability analysis of gravity retaining wall was currently based on the assumption that the wall had no embedment depth. The effect of earth berm was usually neglected. The present work highlighted the importance of e...Stability analysis of gravity retaining wall was currently based on the assumption that the wall had no embedment depth. The effect of earth berm was usually neglected. The present work highlighted the importance of embedment depth when assessing the seismic stability of gravity retaining walls with the pattern of pure rotation. In the framework of upper bound theorem of limit analysis, pseudo-static method was applied into two groups of parallel rigid soil slices methods in order to account for the effect of embedment depth on evaluating the critical acceleration of wall-soil system. The present analytical solution is identical to the results obtained from using limit equilibrium method, and the two methods are based on different theory backgrounds. Parameter analysis indicates that the critical acceleration increases slowly when the ratio of the embedment depth to the total height of the wall is from 0 to 0.15 and increases drastically when the ratio exceeds 0.15.展开更多
Because of its excellent seismic performance, reinforced soil retaining walls are increasingly used in civil engineering. Although many countries have published corresponding design codes, the differences between them...Because of its excellent seismic performance, reinforced soil retaining walls are increasingly used in civil engineering. Although many countries have published corresponding design codes, the differences between them are still relatively large. Using the FHWA Code and the Code for Seismic Design of Railway Engineering(CSDRE), stability calculations of reinforced soil retaining walls were carried out and the similarities and differences between these two design codes were analyzed. According to the comparative analysis, the following conclusions are drawn: the inertia force, the earth pressure and the tensile force of reinforcements calculated from the CSDRE are less than those from the FHWA Code, and the safety factor calculated from the former is larger. Although the M-O method is recommended to calculate the dynamic earth pressure, the FHWA Code suggests a higher action point as compared to the CSDRE.展开更多
The retaining walls in coral sand sites are inevitably threatened by earthquakes. A series of shaking table tests were carried out to study the seismic stability of gravity retaining walls with coral sand backfill. Pa...The retaining walls in coral sand sites are inevitably threatened by earthquakes. A series of shaking table tests were carried out to study the seismic stability of gravity retaining walls with coral sand backfill. Parallel tests with quartz sand were performed to compare and discuss the special dynamic properties of coral sand sites. The results show that the acceleration difference between the retaining wall and the coral sand backfill is 76%-92% that of the quartz sand,which corresponds to the larger liquefaction resistance of coral sand compared with the quartz sand. However, the horizontal displacement of the retaining walls with coral sand backfill reaches 79% of its own width under 0.4g vibration intensity. The risk of instability and damage of the retaining walls with coral sand backfill under strong earthquakes needs attention.展开更多
In engineering practice simplified methods are essential to the seismic design of embedded earth retaining walls,as fullydynamic numerical analyses are costly,time-consuming and require specific expertise.Recently dev...In engineering practice simplified methods are essential to the seismic design of embedded earth retaining walls,as fullydynamic numerical analyses are costly,time-consuming and require specific expertise.Recently developed pseudostatic methods provide earth stresses and internal forces,even in those cases in which the strength of the soil surrounding the structure is not entirely mobilised.Semiempirical correlations or Newmark sliding block method provide an estimate of earthquake-induced permanent displacements.However,the use of these methods is hindered by uncertainties in the evaluation of a few input parameters,affecting the reliability of the methods.This study uses 1 D site response analyses and 2 D fully-dynamic finite element analyses to show that simplified methods can provide a reasonable estimate of the maximum bending moment and permanent displacements for stiff cantilever walls embedded in uniform sand,providing that a few input parameters are evaluated through semiempirical correlations and a simple 1 D site response analysis.展开更多
According the Coulomb earth pressure theory,it is obtained that,for normally consolidated soils,the lateral pressure coefficient of a soil at rest is equal to 1,and it is independent of the soil type,either granular o...According the Coulomb earth pressure theory,it is obtained that,for normally consolidated soils,the lateral pressure coefficient of a soil at rest is equal to 1,and it is independent of the soil type,either granular or cohesive;or that the material is in a loose or compact state;hard or a soft cohesive soil.Also,a methodology to calculate the earth pressure for intermediate states between at rest condition and the active pressure is presented.In addition,a methodology to calculate the earth pressure for intermediate states between at rest condition and the passive pressure is presented.Two practical examples are presented:one for a frictionless wall;and another for a coarse wall.Practical recommendations are given for the use of the lateral earth pressure coefficient for different applications.展开更多
基金funding support from National Natural Science Foundation of China(Grant No.52179109)Jiangsu Provincial Natural Science Foundation(Grant No.BK20230967)Open Research Fund of State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(Grant No.KF2022-02).
文摘Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests.
基金supported by the National Key R&D Program(No.2018YFC1504901)and by the Natural Science Foundation of China(Grant No.42071264)supported by the Geological Hazard Prevention Project in The Three Gorges Reservoirs(Grant No.0001212015CC60005).
文摘An analytical method for determining the stresses and deformations of landfills contained by retaining walls is proposed in this paper.In the proposedmethod,the sliding resisting normal and tangential stresses of the retaining wall and the stress field of the sliding body are obtained considering the differential stress equilibrium equations,boundary conditions,and macroscopic forces and moments applied to the system,assuming continuous stresses at the interface between the sliding body and the retaining wall.The solutions to determine stresses and deformations of landfills contained by retaining walls are obtained using the Duncan-Chang and Hooke constitutive models.A case study of a landfill in the Hubei Province in China is used to validate the proposed method.The theoretical stress results for a slope with a retaining wall are compared with FEMresults,and the proposed theoreticalmethod is found appropriate for calculating the stress field of a slope with a retaining wall.
基金The research was financially supported by National Natural Science Foundation of China(Grant Nos.52108302 and 52009046)Fundamental Research Funds for the Central Universities of Hua-qiao University(Grant No.ZQN-914).
文摘Soils are not necessarily uniform and may present linearly varied or layered characteristics,for example the backfilled soils behind rigid retaining walls.In the presence of large lateral thrust imposed by arch bridge,passive soil failure is possible.A reliable prediction of passive earth pressure for the design of such wall is challenging in complicated soil strata,when adopting the conventional limit analysis method.In order to overcome the challenge for generating a kinematically admissible velocity field and a statically allowable stress field,finite element method is incorporated into limit analysis,forming finiteelement upper-bound(FEUB)and finite-element lower-bound(FELB)methods.Pseudo-static,original and modified pseudo-dynamic approaches are adopted to represent seismic acceleration inputs.After generating feasible velocity and stress fields within discretized elements based on specific criteria,FEUB and FELB formulations of seismic passive earth pressure(coefficient K_(P))can be derived from work rate balance equation and stress equilibrium.Resorting to an interior point algorithm,optimal upper and lower bound solutions are obtained.The proposed FEUB and FELB procedures are well validated by limit equilibrium as well as lower-bound and kinematic analyses.Parametric studies are carried out to investigate the effects of influential factors on seismic K_(P).Notably,true solution of K_(P) is well estimated based on less than 5%difference between FEUB and FELB solutions under such complex scenarios.
基金Hunan Provincial key Laboratory of key Technology on Hydropower Development Open Research Fund (PKLHD202203)
文摘Rock avalanches are generally difficult to prevent and control due to their high velocities and the extensive destruction they cause.However,barrier structures constructed along the path of a rock avalanche can partially mitigate the magnitudes and consequences of such catastrophic events.We selected a rock avalanche in Nayong County,Guizhou Province,China as a case to study the effect of the location and height of a retaining wall on the dynamic characteristics of rock avalanche by using both actual terrain-based laboratory-model tests and coupled PFC3D-FLAC3D numerical simulations.Our findings demonstrate that a retaining wall can largely block a rock avalanche and its protective efficacy is significantly influenced by the integrity of the retaining wall.Coupled numerical simulation can serve as a powerful tool for analyzing the interaction between a rock avalanche and a retaining wall,facilitating precise observations of its deformation and destruction.The impact-curve characteristics of the retaining wall depend upon whether or not the rock avalanche-induced destruction is taken into account.The location of the retaining wall exerts a greater influence on the outcome compared to the height and materials of the retaining wall,while implementing a stepped retaining-wall pattern in accordance with the terrain demonstrates optimal efficacy in controlling rock avalanche.
基金Project(2013CB036004) supported by the National Basic Research Program of ChinaProjects(51178468,51174086) supported by the National Natural Science Foundation of ChinaProject(201102) supported by the Open Foundation of Hunan Key Laboratory of Safe Mining Techniques of Coal Mines,China
文摘In order to reduce the errors of the reliability of the retaining wall structure in the establishment of function, in the estimation of parameter and algorithm, firstly, two new reliability and stability models of anti-slipping and anti-overturning based on the upper-bound theory of limit analysis were established, and two kinds of failure modes were regarded as a series of systems with multiple correlated failure modes. Then, statistical characteristics of parameters of the retaining wall structure were inferred by maximal entropy principle. At last, the structural reliabilities of single failure mode and multiple failure modes were calculated by Monte Carlo method in MATLAB and the results were compared and analyzed on the sensitivity. It indicates that this method, with a high precision, is not only easy to program and quick in calculation, but also without the limit of nonlinear functions and non-normal random variables. And the results calculated by this method which applies both the limit analysis theory, maximal entropy principle and Monte Carlo method into analyzing the reliability of the retaining wall structures is more scientific, accurate and reliable, in comparison with those calculated by traditional method.
基金the National Program on Key Research Project of China (Grant No. 2016YFC0802206)the open research fund of MOE Key Laboratory of High-speed Railway Engineering,Southwest Jiaotong University and Doctoral Innovation Fund Program of Southwest University of Science and Technology (Grant No. 16zx7123)
文摘This study investigated the influence factors on the seismic response and deformation modes of retaining walls using large-scale model shaking table tests. Experimental results showed that the distribution of peak seismic earth pressures along the height of a wall was a single peak value curve. The seismic earth pressures on a gravel soil retaining wall were larger than the pressures on the weathered granite and quartz retaining walls. Also, the peak seismic earth pressure increased with increases in the peak ground acceleration and the wall height. The measured seismic active earth pressures on a rock foundation retaining wall were larger than the calculated values, and the action position of resultant seismic pressure was higher than 0.33 H. In the soil foundation retaining wall, the measured seismic earth pressures were much smaller than the calculated values, while the action position was slightly higher than 0.33 H. The soil foundation retaining wall suffered base sliding and overturning under earthquake conditions, while overturning was the main failure mode for the rock foundation retaining walls.
文摘Dynamic earth pressure induced by machine foundations on a neighboring retaining wall is analyzed with emphasis on factors which control the intensity and location of the design forces. The meshless local Petrov-Galerkin (MLPG) method is used to analyze the problem for a variety of retaining wall and machine foundation geometries. The soil medium is assumed to be homogeneous and visco-elastic. The machine foundation is idealized as a harmonic sinusoidal dynamic force often encountered in practice. A number of analyses have been made to reveal the effect of the loading frequency, the location and size of the foundation and the soil shear wave velocity on the distribution and magnitude of the dynamic earth pressure. Results indicate that there is a critical frequency and a critical location for which the passive pressure takes the maxima in the entire duration of the dynamic load.
基金supported by the Development Bureau of Hong Kong SAR Government,a Research Impact Fund(RIF)project(Grant No.R5037-18)a Theme-based Research Scheme Fund(TRS)project(Grant No.T22-502/18-R)a General Research Fund(GRF)projects(Grant No.PolyU 152130/19E)from Research Grants Council(RGC)of Hong Kong SAR.
文摘Hong Kong has a long history of applying masonry retaining walls to provide horizontal platforms and stabilize man-made slopes.Due to the sub-tropical climate,some masonry retaining walls are colonized by trees.Extreme weather,such as typhoons and heavy rains,may cause rupture or root failure of those trees,thus resulting in instability of the retaining walls.A monitoring and warning system for the movement of masonry retaining walls and sway of trees has been designed with the application of fiber Bragg grating(FBG)sensing technology.The monitoring system is also equipped with a solar power system and 4G data transmission devices.The key functions of the proposed monitoring system include remote sensing and data access,early warning,and real-time data visualization.The setups and working principles of the monitoring systems and related transducers are introduced.The feasibility,accuracy,serviceability and reliability of this monitoring system have been checked by in-site calibration tests and four-month monitoring.Besides,a two-level interface has been developed for data visualization.The monitoring results show that the monitored masonry retaining wall had a reversible movement up to 2.5 mm during the monitoring period.Besides,it is found that the locations of the maximum strain on trees depend on the crown spread of trees.
文摘In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wallmodels retaining composite backfill made of a deformable geofoam inclusion and granular cohesionlessmaterial were presented. Two different polystyrene materials were utilized as deformable inclusions.Lateral dynamic earth pressures and wall displacements at different elevations of the retaining wallmodel were monitored during the tests. The earth pressures and displacements of the retaining wallswith deformable inclusions were compared with those of the models without geofoam inclusions.Comparisons indicated that geofoam panels of low stiffness installed against the retaining wall modelaffect displacement and dynamic lateral pressure profile along the wall height. Depending on the inclusioncharacteristics and the wall flexibility, up to 50% reduction in dynamic earth pressures wasobserved. The efficiency of load and displacement reduction decreased as the flexibility ratio of the wallmodel increased. On the other hand, dynamic load reduction efficiency of the deformable inclusionincreased as the amplitude and frequency ratio of the seismic excitation increased. Relative flexibility ofthe deformable layer (the thickness and the elastic stiffness of the polystyrene material) played animportant role in the amount of load reduction. Dynamic earth pressure coefficients were compared withthose calculated with an analytical approach. Pressure coefficients calculated with this method werefound to be in good agreement with the results of the tests performed on the wall model having lowflexibility ratio. It was observed that deformable inclusions reduce residual wall stresses observed at theend of seismic excitation thus contributing to the post-earthquake stability of the retaining wall. Thegraphs presented within this paper regarding the dynamic earth pressure coefficients versus the wallflexibility and inclusion characteristics may serve for the seismic design of full-scale retaining walls withdeformable polystyrene inclusions. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
基金Project(41472245)supported by the National Natural Science Foundation of ChinaProject(CQGT-KJ-2014049)supported by the Chongqing Administration of Land,Resources and Housing,ChinaProject(106112014CDJZR200009)supported by the Fundamental Research Funds for the Central Universities,China
文摘Stability analysis of gravity retaining wall was currently based on the assumption that the wall had no embedment depth. The effect of earth berm was usually neglected. The present work highlighted the importance of embedment depth when assessing the seismic stability of gravity retaining walls with the pattern of pure rotation. In the framework of upper bound theorem of limit analysis, pseudo-static method was applied into two groups of parallel rigid soil slices methods in order to account for the effect of embedment depth on evaluating the critical acceleration of wall-soil system. The present analytical solution is identical to the results obtained from using limit equilibrium method, and the two methods are based on different theory backgrounds. Parameter analysis indicates that the critical acceleration increases slowly when the ratio of the embedment depth to the total height of the wall is from 0 to 0.15 and increases drastically when the ratio exceeds 0.15.
基金sponsored by the Project of Science and Technology Research and Development Plan of China Railway Corporation(Grant No.2014G003-C)
文摘Because of its excellent seismic performance, reinforced soil retaining walls are increasingly used in civil engineering. Although many countries have published corresponding design codes, the differences between them are still relatively large. Using the FHWA Code and the Code for Seismic Design of Railway Engineering(CSDRE), stability calculations of reinforced soil retaining walls were carried out and the similarities and differences between these two design codes were analyzed. According to the comparative analysis, the following conclusions are drawn: the inertia force, the earth pressure and the tensile force of reinforcements calculated from the CSDRE are less than those from the FHWA Code, and the safety factor calculated from the former is larger. Although the M-O method is recommended to calculate the dynamic earth pressure, the FHWA Code suggests a higher action point as compared to the CSDRE.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41831282 and 51878103)the Fundamental Research Funds for the Central Universities(Grant No.2021CDJQY-042)Chongqing Talents Program(Grant No.cstc2021ycjh-bgzxm0051).
文摘The retaining walls in coral sand sites are inevitably threatened by earthquakes. A series of shaking table tests were carried out to study the seismic stability of gravity retaining walls with coral sand backfill. Parallel tests with quartz sand were performed to compare and discuss the special dynamic properties of coral sand sites. The results show that the acceleration difference between the retaining wall and the coral sand backfill is 76%-92% that of the quartz sand,which corresponds to the larger liquefaction resistance of coral sand compared with the quartz sand. However, the horizontal displacement of the retaining walls with coral sand backfill reaches 79% of its own width under 0.4g vibration intensity. The risk of instability and damage of the retaining walls with coral sand backfill under strong earthquakes needs attention.
文摘In engineering practice simplified methods are essential to the seismic design of embedded earth retaining walls,as fullydynamic numerical analyses are costly,time-consuming and require specific expertise.Recently developed pseudostatic methods provide earth stresses and internal forces,even in those cases in which the strength of the soil surrounding the structure is not entirely mobilised.Semiempirical correlations or Newmark sliding block method provide an estimate of earthquake-induced permanent displacements.However,the use of these methods is hindered by uncertainties in the evaluation of a few input parameters,affecting the reliability of the methods.This study uses 1 D site response analyses and 2 D fully-dynamic finite element analyses to show that simplified methods can provide a reasonable estimate of the maximum bending moment and permanent displacements for stiff cantilever walls embedded in uniform sand,providing that a few input parameters are evaluated through semiempirical correlations and a simple 1 D site response analysis.
文摘According the Coulomb earth pressure theory,it is obtained that,for normally consolidated soils,the lateral pressure coefficient of a soil at rest is equal to 1,and it is independent of the soil type,either granular or cohesive;or that the material is in a loose or compact state;hard or a soft cohesive soil.Also,a methodology to calculate the earth pressure for intermediate states between at rest condition and the active pressure is presented.In addition,a methodology to calculate the earth pressure for intermediate states between at rest condition and the passive pressure is presented.Two practical examples are presented:one for a frictionless wall;and another for a coarse wall.Practical recommendations are given for the use of the lateral earth pressure coefficient for different applications.