Investigation on Acoustic Emission Kaiser Effect and Frequency Spectrum Characteristics of Rock Joints Subjected to Multilevel Cyclic Shear Loads

Table 5

Acoustic emission spectrum characteristics in different failure forms of rocks.

Test types	Rock types	Dominant frequency distribution/kHz	Frequency spectrum characteristics	References
Uniaxial compression test	Sandstone	10-70 kHz (much); 120-180 kHz (few)	As the test progresses, low frequency increases, high frequency decreases	Wang et al. [30]
True triaxial compression test	Limestone	60-110 kHz, 170-190 kHz	Low-amplitude and high-frequency signal (low stress); High-amplitude and low-frequency signal (high stress)	He et al. [28]
Direct tensile test	Marble	14-86 kHz, 200-268 kHz (more than 90%)	Tensile failure is more than shear failure	Li et al. [33]
Brazil tensile test	Shale	100–150 kHz (60.02%); 150–250 kHz (11.26%); 250–350 kHz (28.72%)	Friction signal; Shearing signal; Tensile (tearing) signal	Ban et al. [34]
Three-point bending test	Concrete	50-250 kHz	High frequency (microcracks); Low frequency (macrocracks)	Chen et al. [36]
Joint shear test	Skarn	5~35 kHz (less than 5%); 35~122 kHz (more than 90%); 122~170 kHz (less than 5%)	Low-amplitude and high-frequency signal (low stress); High-amplitude and low-frequency signal (high stress)	This paper