Abstract：The mechanical properties of rock may change dramatically due to porous water，discontinuity and sub-zero temperature. The traditional principles of thermodynamics, however, can not solve this problem or explain the phenomena. Based on the principles of irreversible thermodynamics and the mechanics of continuous medium, the continuity equation, equilibrium equation and energy conservation equation can be coupled via some simplified assumptions. Moreover，the relationship between rock and ice in a frozen rockmass is studied and a coupled coefficient of expansion is proposed. It gives a new theoretical basis for studying temperature, seepage and stress distribution in rock mass in cold regions.
