DEFORMATION AND FAILURE CHARACTERISTICS OF GRANITE UNDER UNIAXIAL COMPRESSION AFTER HIGH TEMPERATURE

In this paper,the TAW-2000 servo triaxial testing machine and acoustic emission testing equipment are used to analyze the characteristics of granite under uniaxial compression at 25~650℃ after high temperature. The variation rules of longitudinal wave velocity,maximum strength and AE counts with time are analyzed respectively. The results show that the P-wave velocity and the maximum strength of granite decrease with the increase of temperature. When the temperature exceeds 500℃,the P-wave velocity and the maximum strength begin to decrease greatly. It can be observed that the threshold temperature of granite is about 500℃. The acoustic emission signal is always accompanied by the loading process of granite after high temperature action,and has a good corresponding relationship with the stress versus time curve. The acoustic emission activity of granite after different temperature actions is different. The higher the temperature is,the stronger the acoustic emission activity is. Before 500℃,the granite samples show splitting failure,and the temperature reaches 500℃,the granite samples show shear failure. The high temperature causes the internal structure of granite samples to change and the cracks in the samples gradually expand,penetrate,and finally destroy.