Study thermo-hydro-mechanical coupling behaviors of saturated frozen soil based on granular solid hydrodynamics theory

Based on non-equilibrium thermodynamic theory and granular solid hydrodynamic (GSH), a thermodynamic constitutive model for saturated frozen soil is developed. According to continuum mechanics, mass, momentum, energy conservation equations are presented in which the water–ice phase transformation in frozen soil is taken into consideration. By introducing the GSH theory concepts, the entropy balance and granular entropy equations of saturated frozen soil are built. The thermodynamic state variables describing mechanical field, temperature field and seepage field for saturated frozen soil are introduced. Combining energy conservation with thermodynamic state equations, the kinetic equations are given to build a fully coupled thermo-hydro-mechanical (THM) equations of saturated frozen soil. From the thermodynamic kinetic equations, the inelastic strain and total stress equations are formulated. The thermodynamic constitutive model for saturated frozen soil is proposed, based on non-equilibrium thermodynamic and granular solid hydrodynamic. A series of cryogenic triaxial tests at −6 °C on saturated frozen sandy soil under different confining pressures were conducted to verify the proposed thermodynamic constitutive model. Comparing experimental results with modeling results, the model predictions can agree well with the experimental data. Then the model parameters sensitivity discussions are given.