Research on anisotropic characteristics and energy damage evolution mechanism of bedding coal under uniaxial compression

Abstract

Bedding structures are commonly present in the underground coal mine pillar rock mass, posing a certain threat to its stability. In order to gain a deeper understanding of the damage, destruction, and energy conversion of bedding coal, uniaxial compression experiments were conducted on bedding coal samples. The research results reveal that the compressive strength of coal is highest when the bedding dip angle is 0° (28.74 MPa), followed by 30° and 90° (15.03 and 14.02 MPa), and lowest at 60° (10.03 MPa). The damage evolution curve of coal at a bedding dip angle of 60° exhibits an early sharp increase, indicating that macroscopic damage is easily induced along the bedding planes under this condition. As the bedding dip angle increases from 0° to 90°, the degree of damage to coal under energy drive exhibits a pattern of difficulty-ease-difficulty. When the bedding dip angle is 0°, the coal sample fractures steadily as cracks expand. At 30°, the failure process involves a gradual and steady expansion of cracks followed by an unstable extension. At 60° and 90°, the fractures result in sudden and unstable damage. Furthermore, this study explores the inherent mechanisms of anisotropy and the evolution models of damage in bedding coal.