Safety top-coal-caving of heavy and steep coal seams under complex environment

The seam angle is 64°+ and the mining level height is 54 m at the + 579E2EB₁₊₂ top-coal-caving working face in Weihuliang Mine in northwestern China. Theoretical analysis, numerical calculation and field test were used to study roof collapse and gas overlimit in mined-out area during mining on the working face. The results show that fast mining, control symmetrical top-coal caving in dipping and strike directions, optimizing the ventilation system, and the initiative in preventing gas are valid for safety mining.