Heat-water-stress Coupling Model for Saturated Frozen Soil under Different Stress Levels

Ground deformation induced by frost heave is a matter of concern in cold region engineering construction since it affects surrounding structures. Frost heave, which is related to the heat-water-stress interaction, is a complicated process. In this study, a heat-water-stress coupling model was established for saturated frozen soil under different stress levels to quantify the water redistribution, heat transfer, frost heave, and water intake. An empirical formula for the soil permeability considering the confining and deviator pressures was employed as an indispensable hydraulic equation in the coupling model. The Drucker-Prager yield criterion matched with the Mohr-Coulomb criterion was employed in the force equilibrium equation to investigate the deformation due to the deviator and confining pressures. The anisotropic frost heave during unidirectional freezing was further considered in the coupling model by introducing an anisotropic coefficient. Subsequently, based on the above coupling relationship, a mathematical module in COMSOL Multiphysics was applied to calculate the governing equation numerically. Finally, the proposed model was validated through an existing frost heave experiment conducted under various temperature gradients and stress levels. The results of the freezing front, water redistribution, water intake, and frost heave ratio predicted using the proposed model were found to be consistent with the experimental results.