Research on the constitutive relation of geomaterials based on the theory of internal variable

The problems and limitations in constitutive theory of classical elastoplastic mechanics are discussed by analyzing constitutive models of geomaterials based on the constitutive theory.According to the principle of the modern continuum thermomechanics and the internal variable theory of the modern continuum mechanics,the physical meaning of the yield function in constitutive models of geomaterials and the relation between the yield function and the dissipation function are presented,and a new method to establish elastoplastic constitutive relation of geomaterials is proposed.With the method taken, the elastoplastic matrix of the incremental form of the constitutive equation is deduced,the increment equation of plastic strain is presented,and the generalized normality rule of elastoplastic coupling materials is proved.The problems,which are needed to be further studied,in establishing the elastoplastic constitutive relation of geomaterials by the internal variable theory,are also presented.