Study on coal wall spalling characteristics and stability control of steeply inclined coal seam mining face

Coal wall spalling characteristics and stability control mechanisms in steeply inclined coal seam (SICS) mining are more complex and dynamic due to the imbalanced mechanical constraint environment of the coal wall. This study investigates the characteristics of coal wall spalling in SICS mining using field measurements, theoretical analysis, and numerical simulations. The internal relationship between coal wall spalling and different influencing factors is also established, and the corresponding coal wall stability control measures are put forward. Results indicate that the primary form of coal wall spalling is wedge-shaped. Under the combined action of roof pressure and gravity, the wedge body produces two components along the dip and strike directions, forming two structural planes, a and b. The a-plane predominantly experiences shear slip failure, while the b-plane primarily undergoes tensile failure. The failure criteria for the a-plane and b-plane of the wedge body are determined, with mining height, coal strength, roof pressure, and coal seam dip angle being the main influencing factors in SICS mining. The stability relationship of the coal wall under various advancing distances is investigated using the 3DEC numerical simulation. The majority of coal wall spalling occurs as an asymmetric wedge body, and the relationship between different influencing factors and coal wall spalling is examined. A comprehensive preventive and control technique for coal wall spalling in SICS mining is proposed. The engineering application demonstrates positive results and provides theoretical and technical guidance for the prevention and control of coal wall spalling in SICS mining.