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 degrees C. (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.