A TIME-DEPENDENT THERMO-MECHANICAL CREEP MODEL OF ROCK

A coupled thermo-mechanical creep model of brittle rocks under constant temperatures is proposed based on the theory of rock deformation and thermodynamics. In the model, the heterogeneity of the rock is incorporated. Both the maximum tensile stress criterion and Mohr-Coulomb criterion are used to control tensile damage and shear damage in brittle rocks, and finite element formulation is implemented into COMSOL Multiphysics. A series of numerical simulations are performed and the numerical model is validated against experimental data. Numerical simulations show that the proposed model well captures the typical three creep stages, i.e., primary creep, secondary creep, and tertiary creep of rocks under different constant temperatures. Moreover, numerically simulated cumulative AE counts is consistent with the trend in axial strain of rock, and there are clusters of AE counts during the initial primary creep stage and the tertiary creep stage.