The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationshi...The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationship between the aging time and the overconsolidation parameter is built.With the reloading equation of the UH model(unified hardening model for overconsolidated clays) used to calculate the instant compression deformation,a one-dimensional stress-strain-time relationship is proposed.Furthermore,the evolution of this relationship is analyzed,and the characteristic rate that is a function of the overconsolidation parameter is defined.Then a three-dimensional elastic-viscous-plastic constitutive model is suggested by incorporating equivalent time into the current yield function of the UH model.The new model can describe not only creep,rate effect and other viscous phenomena,but also shear dilatancy,strain softening and other behaviors of overconsolidated clays.Besides,compared with the modified Cam-clay model it requires only one additional parameter(the coefficient of secondary compression) to consider the creep law.Finally,because the proposed model can be changed into the UH model under instantaneous loading,the elastic-plastic and elastic-viscous-plastic frameworks are unified.展开更多
The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured clays.Viscosity coupled with destructuration is analysed based on experimental observations.A strain-rate bas...The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured clays.Viscosity coupled with destructuration is analysed based on experimental observations.A strain-rate based model is developed to de-scribe the mechanical behaviour for both unstructured and structured clays under one-dimensional loading.The advantage of the proposed model lies in the determination of model parameters in a straightforward way,which leads to an easy use of the model for practical problems.Coupled with consolidation,the model is used to simulate oedometer tests at constant rate of strain and long-term creep oedometer tests on two structured clays.All comparisons between predicted and measured results demonstrate that the proposed model can reasonably describe the effect of destructuration on the time-dependent behaviour of soft structured clay under one-dimensional condition.Although the model is proposed for one-dimensional analysis,it can be a good base for developing a more general 3D model.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 51179003,11072016,11272031)the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No.20091102110030)
文摘The influences of time on clays are discussed first,and the concept of the instant normal compression line is proposed by analyzing the existing theories and experimental results.Based on the creep law,the relationship between the aging time and the overconsolidation parameter is built.With the reloading equation of the UH model(unified hardening model for overconsolidated clays) used to calculate the instant compression deformation,a one-dimensional stress-strain-time relationship is proposed.Furthermore,the evolution of this relationship is analyzed,and the characteristic rate that is a function of the overconsolidation parameter is defined.Then a three-dimensional elastic-viscous-plastic constitutive model is suggested by incorporating equivalent time into the current yield function of the UH model.The new model can describe not only creep,rate effect and other viscous phenomena,but also shear dilatancy,strain softening and other behaviors of overconsolidated clays.Besides,compared with the modified Cam-clay model it requires only one additional parameter(the coefficient of secondary compression) to consider the creep law.Finally,because the proposed model can be changed into the UH model under instantaneous loading,the elastic-plastic and elastic-viscous-plastic frameworks are unified.
文摘The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured clays.Viscosity coupled with destructuration is analysed based on experimental observations.A strain-rate based model is developed to de-scribe the mechanical behaviour for both unstructured and structured clays under one-dimensional loading.The advantage of the proposed model lies in the determination of model parameters in a straightforward way,which leads to an easy use of the model for practical problems.Coupled with consolidation,the model is used to simulate oedometer tests at constant rate of strain and long-term creep oedometer tests on two structured clays.All comparisons between predicted and measured results demonstrate that the proposed model can reasonably describe the effect of destructuration on the time-dependent behaviour of soft structured clay under one-dimensional condition.Although the model is proposed for one-dimensional analysis,it can be a good base for developing a more general 3D model.
