Analysis of characteristics of acoustic emission and energy of of gas-bearing coal during unloading confining pressure

A series of confinement unloading tests have been performed on coal specimens containing gas by using a servo-controlled triaxial stress thermal-device and acoustic emission (AE) monitoring system, test results show that AE rate and accumulative counts have a good corresponding relationship with stress curve under different confining pressures, the amplitude is between42,60dB, with amplitude increasing, the rate of AE event decreases; when failure, rate of AE event and confining pressure show linear relationship, and AE cumulative count and confining pressure is an exponential function; during axial stress loading stage and unloading stage of confining pressure, energy feature is different, with the increase of confining pressure, during absorbed energy coal loading stage increases, during released energy the unloading stage increases, the energy change and during the initial loading stage and unloading confining pressure there is a logarithmic relationship.