Experimental Study on the Mechanical Properties and Acoustic Emission Characteristics of Different Bedding High-Rank Coals

Bedding has an important influence on the macroscopicand microscopicmechanical properties of coal, and the mechanical properties of coaland rock mass and acoustic emission characteristics are very importantfor rock burst monitoring and warning. In order to explore the influenceof different beddings on the mechanical properties and acoustic emissioncharacteristics of high-rank coal, using the RMT-150B electrohydraulicservo rock mechanics test system and the DS5 acoustic emission analyzer,the uniaxial compression and acoustic emission characteristics ofhigh-rank coals with different beddings (parallel bedding 0 degrees,oblique bedding 30, 45, 60 degrees, and vertical bedding 90 degrees) wereinvestigated. The results show that the uniaxial compressive strengthand deformation modulus of vertical stratified coal samples are thelargest, which are 28.924 MPa and 2.95 GPa, while the average valuesof uniaxial compressive strength and deformation modulus of obliquestratified coal samples are the smallest, which are 10.91 MPa and1.776 GPa, respectively. With the increase of the bedding angle, theuniaxial compressive strength of high-rank coal decreases first andthen increases. The stress-strain process of coal varies greatlywith different high stratification grades (parallel bedding 0 degrees,oblique bedding 30 degrees, 45 degrees, 60 degrees and vertical bedding90 degrees). The loading times of parallel, oblique, and vertical beddingsare 700, 450, 370, 550, and 600 s, and the acoustic emission mutationpoint values are 495, 449, 350, 300, and 410 s. The mutation pointvalue can be used as precursor information to judge the failure ofhigh-rank coal in different beddings. Research results to find thehigh-rank coal destruction instability prediction method and the indexprovide a basis; further damage to the acoustic emission testing highorder coal provides reference significance; and the use of acousticemission in the monitoring and early warning of percussive groundpressure, the bedding surface of coal, and the actual stress on siteshould be considered.