Study Of Elastoplastic Constitutive Models Effected By Stress Level For Soil

With the fast development of economy, cumulative plastic strain will beproduced， resulting in unusually working of the engineering structures in coastalcities and inland cities where lots of structures were built on soft clays. Therefore, it isimportant to establish a constitutive model which can predict the soil properties undercyclic loading.Based on the bounding surface theory, a primary elasto-plastic bounding surfaceconstitutive model is formulated, which introduces the yielding surface of Cam Claymodel, the mobile mapping center, and a new interpolation function whose parametershave clear meaning.In order to determine the model parameters and verify the rationality of themodel, a series of triaxial compression tests and cyclic triaxial compression tests onconsolidated soft clay are conducted on static and dynamic triaxial apparatus. Then,the method of determining the model parameters effected by stress level is establishedafter the relationship between the model parameters and the stress level is analyzed. Inthe end, the results of the model simulations give an encouraging agreement with theexperiment dates from triaxial compression and tensile tests subjected to differentstress level cycle loading conditions.In order to analysis the influence of intermediate principal stress, the model isextended to the three-dimensional model by the transformed stress method, so as tosolve the engineering problems.In the end, based on the critical state theory, and the subloading surface theory, aprimary elasto-plastic constitutive model is formulated, which introduces the yieldingsurface of Cam Clay model as the usual yield surface and subloading surface, thereversal points of stress path as the similarity centers.