Acoustic Emission Characteristics and Energy Evolution of Granite Subjected to Uniaxial Compression

In order to obtain the precursory characteristics of rock dynamic disasters such as rock burst, based on effectiveness of energy evolution and acoustic emission detection method for rock failure prediction, mechanical parameters, acoustic emission signals and energy of granite under uniaxial loading-unloading cycles were studied by using GAW-2000 electrohydraulic servo rigid press machine controlled by computer and PCI-2 acoustic emission acquisition system. Peak strength of granite under cyclic loading and unloading decreased by about 18% compared with conventional static loading. Ringing count rate was characterized by interval between "sudden increase" and "relative calmness period" before peak strength and the "b" value continued to decrease and to the minimum before instability. Failure represented characteristics of "cracked by step expansion and multiple release of energy". Felicity ratio gradually declined with cycle numbers and it was an important parameter for evaluating rock damage. Containing energy level was used to express rock risk coefficient, accumulation energy was mainly dominant in the pre-peak strength and dissipative energy density was far lower than elastic energy density. Combination of acoustic emission characteristics and energy evolution can improve the accuracy of rock failure prediction.