Study on the Mechanical Properties and Crack Evolution of Bedding Coal under Splitting Load

Abstract

In order to study the tensile properties and crack evolution of bedding coal under splitting load, Brazilian splitting tests were conducted on bedding coal. Results indicate distinct anisotropic mechanical properties of bedding coal. When the bedding dip angle is 0°, the coal sample exhibits the highest tensile strength and splitting modulus, followed by 30° and 90°, with the lowest values observed at 60°. Under the Brazilian splitting load, the crack propagation mechanism for coal samples with a bedding dip angle of 0° involves a combined tension-shear fracture. For dip angles of 0° and 60°, the crack propagation mechanism gradually shifts from tension-shear to tension failure, while at 90°, the crack propagation mechanism is primarily along the bedding plane in tension. The tensile failure characteristics of coal samples with bedding dip angles of 60° and 90° are more pronounced, and the load- acoustic emission parameter curve shows distinct bedding features. In the case of a 30° bedding dip angle, the failure is mainly due to a combined shear and tension cracking, with the acoustic emission counts exhibiting a multi-stage growth pattern. Furthermore, this study explores the implications of bedding coal fracture morphology for fracturing.