Experimental study and engineering application of bolt support based on large-scale sliding coal bump in coal body

As coal mining extends deeper underground, the coal bump brings significant challenges to production safety. As a type of coal bump, the large-scale sliding coal bump of coal body is characterized by overall coal body movement, and the bolt support system is exhibits minimal or no damage. To counteract such geomechanical hazards, the roadway support system must be capable of absorbing energy and reinforcing the coal-rock interface. Critical to this technique is the angle optimization of the support system, as tests demonstrate that bearing capacity is significantly sensitive to the angle of support during interface reinforcement. In this paper, bolts are experimentally simulated using AZ31 magnesium alloy and 5052 aluminum alloy specimens with varying diameters. The failure modes and bearing capacities of bolts are compared at support angles of 30°, 45°, 60°, and 90°. The results show that specimens primarily fail due to tensile forces at support angles of 30° and 45°, while failure is due to shear forces at angles of 60° and 90°. The bearing capacity of specimens is significantly higher under tensile failure compared to shear failure, and energy absorption capacity improves with increasing diameter. The research findings have been applied to the support design of the return airway at the 7305 working face in Kongzhuang Coal Mine.