Abstract：Rock failure induced by thermal stress is called thermal cracking. It is the result of thermal and mechanical coupling. Based on the basic theory of rock deformation and thermodynamics，considering the heterogeneity and the coupling of thermal and mechanics，a numerical model，RFPA2D-thermal code，is proposed. With this model，the temperature and stress fields can be determined. The most important is that the failure process of rock induced by thermal or external stress can be simulated. Using this numerical model，the failure progresses of a rock sample with an inlaid grain was modelled during the change of temperature. It turns out that during temperature increment，if the thermal expansion coefficient of the inlaid grain is larger than that of the surrounding media，radial-cracks will be generated in the surrounding media，and theta-cracks emerge if the thermal expansion coefficient of inlaid grain is smaller than that of the surrounding media. The results agree well with the experimental results. The RFPA2D-thermal model provides a new method for analyzing the thermal cracking of rock samples in microscopic view.
