Acoustic emission characteristics of deep granite under triaxial cylic loading and unloading

In order to obtain the damage and AE characteristics of deep granite, TAW-2000 electrohydraulic servo rigid testing equipment and PCI-2 acoustic emission acquisition system were used to clarify the relationship between AE characteristics and stress level under conventional triaxial and cyclic loading and unloading. The results show that: AE characteristic parameters such as counts and energy under different confining pressures have good consistency in reflecting cracks growth process, which correspond to the stress level of rock sample; Before the critical failure, the AE amplitude increases significantly and extremely high peak frequency and extremely low peak frequency began to appear; The phenomenon that peak frequency band number increases significantly can be used as the precursor of rock failure; The change trend of characteristic parameters, amplitude and peak frequency band were related to the stress level of rock, and the loading path has little influence on it, which verified the effectiveness of AE precursory feature recognition; FR value decreases continuously with the increase of cyclic stress level and overall trend is downward, which indicated that AE memory gradually decreases as the stress level increases; From the perspective of damage mechanics, the AE characteristics of rock before failure are explained reasonably by the development of damage rate.