Multifield Coupled Analysis of Marine Clay under Freeze–Thaw Cycles

A hydro-thermo-chemical-mechanical coupled model is proposed to simulate seasonal marine clay subjected to freeze–thaw cycles. The theoretical model comprehensively considers the nucleation, molecular diffusion, and crystal growth dynamics of moisture and salt, the variation in permeability during the freeze–thaw process, the adsorption and desorption of salt, and the nonconvective flux of the liquid phase. The theoretical model was applied to predict the results of laboratory tests reported in the literature, which verified the accuracy of the proposed model. The effects of temperature gradients and porosity on the phase changes of ice, water, and salt in marine clay were investigated through parametric studies. It is found that the thawing area increases with the number of freeze–thaw cycles. The lower the freezing temperature or the greater the soil porosity, the faster the phase change between water and ice, which hinders the upward migration of water in the bottom part of the soil and inhibits the further formation of ice in the upper part of the soil. Under the calculated conditions, the adsorbed salt content increases approximately threefold, accounting for 17% of the initial salt content after four freeze–thaw cycles.