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

Table 1

Shear strength parameters under different normal force conditions.

Rock joint type	Normal force (kN)	Normal stress (MPa)	Shear loading rate (mm/min)	Number of cyclic hysteresis loop	Shear strength (MPa)	(%)
Joint of skarn (,  mm)	5.0	1.39	2.0	4	1.17	83.84%
	7.5	2.08	2.0	5	1.51	72.77%
	10.0	2.78	2.0	5	1.98	71.38%
	12.5	3.47	2.0	7	2.52	72.70%