Experimental study on characteristics of acoustic emission S-wave and P-wave of granite under shear failure process

Shear acoustic emission monitoring tests of granite were carried out，and S- and P-waves sensors were used to receive acoustic emission signals. The variation rules，and similarities and differences of S- and P-waves signals of acoustic emission are analyzed，and the difference between the two kinds of signals is discussed. The research results show that the variation trend of acoustic emission S-wave and P-wave event rates is inconsistent in the process of shear failure. The P-wave event rate decreases after reaching the maximum value in the elastic stage，there is a“quiet period”before the peak stress，and the cumulative count changes in an“S”shape. The S-wave event rate reaches its maximum value near the peak stress，and the cumulative count changes exponentially. The energy variation trend of S-wave and P-wave is consistent in shear failure process. During the failure process，the energy increases continuously，and the energy rate near the peak stress reaches the maximum value. The cumulative energy increases sharply. The frequency evolution and distribution of acoustic emission S-wave and P-wave signals are obviously different. The main frequency of the P-wave is at six fixed frequencies and approximately evolves in bands. S-wave frequency components are complex and the evolution of main frequency bands is not obvious. The dominant frequency of P-wave is concentrated in the range of 90–110 kHz，while that of S-wave is discrete in the range of 0–500 kHz. Due to the different types of S-wave and P-wave sensors，the response mechanism of different acoustic emission signals with different frequencies of rock failure process is different，which is the reason for the inconsistent variation trend of the number of acoustic emission events between the two sensors. The energy variation trend of S-wave and P-wave acoustic emission events is consistent，which may be related to the low-frequency characteristics of both high-energy signals. The research results further enrich and improve the understanding of acoustic emission signal characteristics of rock fracture process，which is helpful to reveal the mechanism of rock fracture catastrophes. © 2023 Academia Sinica. All rights reserved.