Abstract:Starting from the unloading-reloading modulus and bulk modulus of Duncan-Chang E-B model,elastic component of Gibbs free energy function for soils is formulated based on the thermodynamic principle. Then the incremental stress-strain relationship is obtained by use of the Legendre transformation. The compliance matrices are modified by applying thermodynamic approach,accordingly,the coupling item between elastic volumetric stress(or strain) and elastic deviatoric strain(or stress) behavior is produced. Besides,the material behavior is modeled as elasticity with additional dilatancy term in the bulk modulus due to shear modulus dependent on pressure. In the conventional elastic constitutive model of soils,it is known that there is no relation between shear behavior and dilatancy. The computational results of several closed-loop stress paths indicate that,elastic strain energy non-conservation will be created without consideration of the coupling item. However,the proposed modified model can accurately model elastic component of stress and strain relationship curve of triaxial test. At the same time,energy conservation can be accomplished in a closed stress cycle in the model.