Experimental study of acoustic emission characteristics of granite thermal cracking under middle-high temperature and triaxial stress

The interior physicochemical and structural properties of rock change under middle-high temperature and triaxial stress; and all these Changes would make a series of the acoustic emission phenomena. The law of the acoustic emission of granite sample under triaxial stress (axial pressure 860 kN, confining pressure 1 150 kN) with temperature is primarily studied by experiment. It is shown in this research that: ① The acoustic emission phenomena of rock discontinuously occur under the effect of temperature. ② There is the threshold for the beginning of granite thermal cracking, which is around of 120 ℃. ③ There are 5 stages for the acoustic emission phenomena of granite cracking under the effect of temperature: movement stage of the rock’s original cracking; stage of the acoustic emission before the thermal cracking; the acoustic emission of thermal cracking stage; still stage of the acoustic emission after the large-scale thermal cracking; second thermal cracking stage.