The Behavior Of Overconsolidated Clays Considering The Density Effect

The naturally deposited clays generally exhibit overconsolidated?OC?characteristics initially or after the process of loading and unloading and OC clays behave differently from normally consolidated?NC?clays greatly.So the study on the constitutive models for OC clays has always been a hot and important topic.Researchers from all over the world have done lots of work and scored tremendous achievements.The bounding surface?BS?concept was originally presented by Dafalias and Popov through studying the cyclic loading phenomenon of metals and was applied to isotropic and anisotropic cohesive soils.The subloading surface?SS?concept proposed by Hashiguchi et al.was employed to describe the behavior of elastoplastic materials with elastic-plastic transition,like OC clays.The subloading t_ij model(abbreviate as t_ij model)for OC clays was developed based on the t_ijj model for NC clays by employing the subloading surface concept,and can take into consideration the influence of intermediate principal stresses on the deformation and strength behaviors of OC clays.The unified hardening?UH?model for OC clays was presented by introducing the current yield surface,reference yield surface and the potential strength concepts.The transformed stress tensor was adopted in the model in order to describe the behavior of clays in triaxial stress spaces.These models are compared in this paper.The v-ln p linear relation under the isotropic consolidation condition was employed in the above mentioned models except the subloading surface model.The ln v-ln p linear relation under the isotropic consolidation and the modified expressions of the elastic bulk and shear modules which can characterize the density effect on the deformation behavior of OC clays is introduced.The importance of this modification is verified by integrating it into the UH model for OC clays and comparing the corresponding model predictions with the test results.