ABSTRACT
Based on the principles of mechanics of continua and thermodynamics, the couple equations of the water, heat and stress fields are deduced. It is considered that the volume strain of soil includes elastic part , plastic part from pore water content change, the part from phase change and viscoplastic part. The phenomenon of frozen fringe exists due to the different water migration forces and different temperatures in different sites, and the relationship of water migration forces and temperature meets the demand of phase change. Ice lens can be formed when the phase balance formula is satisfied and the pore water pressure is up to the sum value of the effective stress of soil frame and the cohesion force of soil particles.
