Acoustic emission characteristics of coal rocks under different loading angles

In order to obtain the acoustic emission parameters of different bedding coal and provide reference for the analysis and determination of its fracture mechanism and fracture precursors, the uniaxial compression acoustic emission experimental study of coal samples with bedding angles of 45°, 90° and 0° was carried out, the corresponding relationship between b values of coal samples with different loading angles and stress and energy was analyzed, the variation laws of acoustic emission parameters RA and AF values were studied, and the b value and r value under loading angle of 0 ° were analyzed. The results show that: after the peak stress, a large amount of energy is released, resulting in the penetration of micro cracks into large cracks. The b values of coal samples with loading angles of 45 ° and 90 ° are close to and significantly greater than that of 0 ° coal sample, and the b value of each specimen decreases after reaching the peak stress; when the loading angle is 45 °, the failure form of coal sample is tension shear composite failure. The loading angles of 90 ° and 0 ° are mainly tensile failure; the period of sharp decrease of b value is the same as that of sharp increase of r value, and r value can be used as an index to describe the degree of coal damage.