AN ELASTOPLASTIC MODEL FOR NORMALLY AND OVER CONSOLIDATED SOILS IN GENERAL STRESS SYSTEMS AND ITS APPLICATION TO SOME GEOTECHNICAL PROBLEMS

摘要

An isotropic hardening elastoplastic model for soils is presented, which can describe typical deformation and strength behavior of normally and over consolidated soil under general stress conditions. This model can take into consideration the influence of intermediate principal stress on the deformation and strength of soil upon using the concept of modified stress t_(ij). The influence of stress path on the direction of plastic flow is considered by dividing the plastic strain increment into two components. After inclusion of the parameter ' ρ' and subloading surface concept, this model can express the influence of density and confining pressure on the soil behavior. Only one material parameter a for representing the influence of density is added to the parameters of the previous model, which are fundamentally the same as those of Cam-clay model. The validity of the model is checked by monotonic and cyclic loading tests on normally and over consolidated clays. The model is then applied to the analyses of shallow foundation under various loading conditions and tunnel excavation with different ground depths.