Experimental research on the acoustic emission characteristics of rock under uniaxial compression

All characteristics of acoustic emission in the procedure of rock stress-strain and effect of loading rates were studied experimentally under uniaxial compression by using PAC acoustic emission acquisition system and MTS equipment. The relationship of axial stress with axial strain, transverse strain and volume strain of rock, as well as the characteristics of acoustic emission at four stages of the stress-strain curve were obtained. In initial consolidation and elastic phase, it is found out that hits seldom happens, energy keeps low, amplitude is small and no event is produced. In strain hardening phase, hits instantly increases, energy go up, amplitude enhanced and events happen. In strain softening phase hits decrease, energy became low, amplitude went back small and events happen. Due to the differences among acoustic emission characteristics in individual rock-transforming phases, acoustic emission method can be used to study micro-damage evolvement and predict macro-destabilization of engineering rock mass on spot. The failure damage evolution rule of sandstone under the different loading rates is studied based on the acoustic emission characteristics. The increase of loading rate can promote the rate of crack extension and damage, so there are more AE counts. But, intense AE events being, the energy release at the peak place and strain value decrease.