Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechan...Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechanism,the complete deformation process of deep rock mass,with a great emphasis on local shear deformation stage,was analyzed in detail.The quasi continuous shear deformation of the deep rock mass is described by a combination of smooth functions:the averaged distribution of the original deformation field,and the local discontinuities along the slip lines.Hence,an elasto-plastic model is established for the shear deformation process,in which the rotational displacement is taken into account as well as the translational component.Numerical analysis method was developed for case study.Deformation process of a tunnel under high earth stress was investigated for verification.展开更多
Employing an ideal elasto-plastic model,the typically used strength reduction method reduced the strength of all soil elements of a slope.Therefore,this method was called the global strength reduction method(GSRM).How...Employing an ideal elasto-plastic model,the typically used strength reduction method reduced the strength of all soil elements of a slope.Therefore,this method was called the global strength reduction method(GSRM).However,the deformation field obtained by GSRM could not reflect the real deformation of a slope when the slope became unstable.For most slopes,failure occurs once the strength of some regional soil is sufficiently weakened; thus,the local strength reduction method(LSRM)was proposed to analyze slope stability.In contrast with GSRM,LSRM only reduces the strength of local soil,while the strength of other soil remains unchanged.Therefore,deformation by LSRM is more reasonable than that by GSRM.In addition,the accuracy of the slope's deformation depends on the constitutive model to a large degree,and the variable-modulus elasto-plastic model was thus adopted.This constitutive model was an improvement of the Duncan–Chang model,which modified soil's deformation modulus according to stress level,and it thus better reflected the plastic feature of soil.Most importantly,the parameters of the variable-modulus elasto-plastic model could be determined through in-situ tests,and parameters determination by plate loading test and pressuremeter test were introduced.Therefore,it is easy to put this model into practice.Finally,LSRM and the variable-modulus elasto-plastic model were used to analyze Egongdai ancient landslide.Safety factor,deformation field,and optimal reinforcement measures for Egongdai ancient landslide were obtained based on the proposed method.展开更多
An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to...An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to describe only the envelope of the maximum plastic deformations generated during the cyclic loading process, which can calculate the accumulated deformation by means of relatively large load cycle increments. The concept of volumetric hardening was incorporated into the model and a so-called overstress formulation was employed to describe the evolution of the accumulated volumetric deformation as a state parameter. The model accounted for ratcheting shakedown and accumulation such as a pseudo-yield surface(a shakedown surface) associated with loading inside the current virgin yield surface which was implemented into the well-known modified Cam-clay model. Finally, the model was calibrated using data from the stress-controlled drained cyclic triaxial tests on homogeneous fine grained sands. It is seen that the model can successfully represent important features of the ratcheting accumulation of both volumetric and deviatoric deformation caused by repeated drained loading over a large number of cycles.展开更多
基金Project(50825403) supported by the National Science Fund for Distinguished Young ScholarsProject(2010CB732003) supported by the National Key Basic Research Program of ChinaProject(51021001) supported by the Science Fund for Creative Research Group of the National Natural Science Foundation of China
文摘Deep rock mass possesses some unusual properties due to high earth stress,which further result in new problems that have not been well understood and explained up to date.In order to investigate the deformation mechanism,the complete deformation process of deep rock mass,with a great emphasis on local shear deformation stage,was analyzed in detail.The quasi continuous shear deformation of the deep rock mass is described by a combination of smooth functions:the averaged distribution of the original deformation field,and the local discontinuities along the slip lines.Hence,an elasto-plastic model is established for the shear deformation process,in which the rotational displacement is taken into account as well as the translational component.Numerical analysis method was developed for case study.Deformation process of a tunnel under high earth stress was investigated for verification.
基金Project([2005]205)supported by the Science and Technology Planning Project of Water Resources Department of Guangdong Province,ChinaProject(2012-7)supported by Guangdong Bureau of Highway Administration,ChinaProject(2012210020203)supported by the Fundamental Research Funds for the Central Universities,China
文摘Employing an ideal elasto-plastic model,the typically used strength reduction method reduced the strength of all soil elements of a slope.Therefore,this method was called the global strength reduction method(GSRM).However,the deformation field obtained by GSRM could not reflect the real deformation of a slope when the slope became unstable.For most slopes,failure occurs once the strength of some regional soil is sufficiently weakened; thus,the local strength reduction method(LSRM)was proposed to analyze slope stability.In contrast with GSRM,LSRM only reduces the strength of local soil,while the strength of other soil remains unchanged.Therefore,deformation by LSRM is more reasonable than that by GSRM.In addition,the accuracy of the slope's deformation depends on the constitutive model to a large degree,and the variable-modulus elasto-plastic model was thus adopted.This constitutive model was an improvement of the Duncan–Chang model,which modified soil's deformation modulus according to stress level,and it thus better reflected the plastic feature of soil.Most importantly,the parameters of the variable-modulus elasto-plastic model could be determined through in-situ tests,and parameters determination by plate loading test and pressuremeter test were introduced.Therefore,it is easy to put this model into practice.Finally,LSRM and the variable-modulus elasto-plastic model were used to analyze Egongdai ancient landslide.Safety factor,deformation field,and optimal reinforcement measures for Egongdai ancient landslide were obtained based on the proposed method.
基金Projects(41302219,41302076)supported by the National Natural Science Foundation of China
文摘An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to describe only the envelope of the maximum plastic deformations generated during the cyclic loading process, which can calculate the accumulated deformation by means of relatively large load cycle increments. The concept of volumetric hardening was incorporated into the model and a so-called overstress formulation was employed to describe the evolution of the accumulated volumetric deformation as a state parameter. The model accounted for ratcheting shakedown and accumulation such as a pseudo-yield surface(a shakedown surface) associated with loading inside the current virgin yield surface which was implemented into the well-known modified Cam-clay model. Finally, the model was calibrated using data from the stress-controlled drained cyclic triaxial tests on homogeneous fine grained sands. It is seen that the model can successfully represent important features of the ratcheting accumulation of both volumetric and deviatoric deformation caused by repeated drained loading over a large number of cycles.
