Abstract:The change of rock microstructure with thermo-mechanical coupling effects is the main cause for transformation of macroscopic mechanics of rock. The rheological mechanism of granite with thermo-mechanical coupling effects;and rheological model of granite are researched. As a result,it is a kind of feasible way for building rheological constitutive equation. According to the research on rheological mechanism of granite with thermo-mechanical coupling effects,it knows:(1) Granite is a sort of brittleness and hardness rock constituted with multi-ingredient;it is provided with polycrystal multiple medium and prodigious anisotropic. Microstructure inside of granite can be divided into grain,boundary of grain,intercrystalline cement and intercrystalline pore;such ingredient and structure determine the rheological properties of granite with thermo-mechanical coupling effects. (2) The rheological phenomenon is induced by dislocation and cracking of grain and cement of grain with thermo-mechanical coupling effects,which is a compound rupture process with thermal cracking by temperature and damage cracking by stress. So macro-mechanical properties of mechanical parameters become a function of temperature. Therefore,the viscoelasto-plastic rheological elements of mechanical model combining the phenomenon of rock rheology and physical rheology are proposed;and the rheological model of granite with thermo-mechanical coupling effects on the basis of generalized Nishihara rheological model is constructed. The evolution model is deduced,which can describe 150 MPa and 600 ℃ granite within the evolution of the constitutive equation;and experimental results show its application and rationality. Granite model of the constitutive equation with thermo-mechanical coupling effects provides a basis for the establishment of high- temperature geothermal development drilling rock of stability.