Acoustic Emission Parameter Characterization of Damage Process of the Limestone with Different Rockburst Tendencies

The laboratory discrimination tests of the rockburst tendency and AE tests under the uniaxial compression were conducted on the limestone. Three criterions were used to judge the rockburst tendency of the limestone with a buried depth of 600–1000 m under the same borehole. The rock damages were quantified by the AE events, ring count and energy. The fractal characteristics of these parameters were compared and analyzed. The characterization accuracy of these parameters on the damage process of the limestone with different rockburst tendencies was discussed. The AE parameters of the limestone with different rockburst tendencies increase sharply when the stress is near its peak. With the increase in the rockburst tendency, the variation of the AE event rate and ring count of the limestone is more and more consistent with the AE energy. Based on the characterization of the AE events and ring count, the damage process is characterized by a gradual evolution, while based on the energy characterization, it is characterized by a stepped evolution. The damage represented by the AE energy reveals the intensity and instantaneity of the rockburst failure. According to the verification of the CV value, the fractal dimension D of the AE energy fluctuates more gently with the increase in the rockburst tendency. It reflects the energy storage characteristics of the rock with a rockburst tendency in the loading process, which is consistent with the failure mechanism of the rockburst. Therefore, AE energy is more accurate to characterize and predict the failure of the limestone with a rockburst tendency.