Abstract:Based on the thermomechanical approach to establish elasticplastic constitutive model for geomaterials and analysis of thermomechanical model proposed by Collins,its shortage of hardening law is improved by incorporating unified hardening parameters,then the unified model which is suitable for both clay and sand is presented.After the threedimension being generalized,the finite element method (FEM) computer program of thermomechanical model and the improved model which consider the deformation characters of traditional triaxial test are worked out.Then the improved program is used to simulate traditional triaxial compression tests of Shanghai silt sand,the rationality and validity of the improved model can be seen from the comparison of the calculated results.