Experimental study on mechanical properties of granite subjected to cyclic loads under real time temperature

The uniaxial stress-strain tests of granite under different temperatures and cyclic loads were performed utilizing the multi-functional rock high temperature triaxial testing machine, and the effect of the temperature and the cyclic load on the mechanical properties of granite was revealed. The results show that the uniaxial compressive strength and elastic modulus of granite decrease generally with increasing the temperature. The ultimate strain changes with the temperature in W shape. Specifically, the ultimate strain of granite firstly decreases with rising the temperature from 25℃ to 200℃, secondly increases from 200℃ to 300℃, thirdly decreases from 300℃ to 500℃ and then increases from 500℃ to 600℃. The elastic modulus of granite increases generally due to cyclic loads, and the increase amplitude is different with different temperatures with the minimum and maximum values at 100℃ and 400℃ respectively. The increase of the elastic modulus mainly occurs in the second stress cycle but is not obvious from the second to the 50th stress cycle. At 25℃ and 600℃, granite samples fail after a limited number of stress cycles, and the strength is lower than that without stress cycle. However, the strength of the samples after stress cycle shows different degrees of increase at other temperatures. The ultimate strain of granite subjected to 50 stress cycles is greater than that without stress cycle at 100℃ and 400℃ but changes slightly at other temperatures. The research results have important theoretical significance and application value for the study of engineering stability under the simultaneous action of temperature and cyclic stress. © 2019, Science Press. All right reserved.