Abstract: In order to investigate and analyze the damage mechanism and evolution rule of the physical and mechanical properties of granite under the action of multiple high temperature-water cooling cycle at different temperatures, high temperature-water cooling cycle test, uniaxial compressive strength test, ultrasonic test were carried out. The results show that: 1) At the same temperature, an increase in the number of high temperature-water cooling cycle results in the initiation and expansion of the internal fractures of the rock sample, which is manifested by the gradual increase of the mass loss rate of granite samples. And the compressive strength and elastic modulus decrease firstly, then increase slightly, and finally continue to decline. 2) When the number of high temperature-water cooling cycle is the same, an increase of temperature leads to a continuous increase in the mass loss of the granite samples, and a continuous decrease in the compressive strength and elastic modulus. 3) Temperature has a large effect on the P-wave velocity of granite. As the temperature increases, the wave velocity decreases rapidly and the amplitude becomes unstable. 4) The increase of temperature and the number of high temperature-water cooling cycle both increase the damage degree of rock samples and the damage variables. 5) With the increase of temperature and the number of high temperature-water cooling cycle, the rock sample gradually softens, and its uniaxial compression failure mode transitions from splitting tensile failure to conical shear failure. The number of cracks on the surface gradually increases during failure. Additionally, tree-like cracks appear when the temperature is up to 400 ℃ and gradually penetrate the entire surface. It is concluded that the physical and mechanical properties of granite will be severely degraded after high temperature-water cooling cycle.

Key words: high temperature, water cooling cycle, compressive strength, damage variable, crack characteristics