A fully coupled thermo-hydro-mechanical model for rock mass under freezing/thawing condition

The coupled thermo-hydro-mechanical (THM) process in rock mass under freezing/thawing condition is studied. The governing equations for THM coupling of freezing/thawing rock are established based on the mass conservation law, energy conservation law and the principle of static equilibrium. The phase change of water in the rock is studied, and the frozen ratio function considering time-dependent behavior is proposed. Finally, we implement the THM coupling equations under freezing/thawing condition into three-dimensional finite-difference program to simulate the cooling test of an underground cavern for gas storage at low temperature. The distribution of temperature and stress fields is monitored and compared with the recorded results from field test, which shows that the simulation result is close to the field test.