Research on the yield function of sand based on thermodynamics

It is well known that stress-strain relation of sand is influenced by anisotropic fabric. In this paper, the relationship between macroscopic strain and shear strain and its pore structure is established by combining micromechanical theory and pore structure tensor. It is further confirmed that the stress-induced anisotropy and dilatancy of sand are inevitable. Based on this, with the help of thermodynamic theory, the inclined elliptic yield surface function in dissipative space is built, and there are three important lines in dissipative space for the influence of anisotropic fabric, normal consolidation line, phase transition line and peak line respectively corresponding to the three characteristic lines of real stress space: normal consolidation line, phase transition line and peak line which really reflects the mechanical properties of sand, especially dense sand.