Longwall mining method with roof-cutting unloading and numerical investigation of ground pressure and roof stability

As the energy demand for economic development continues to increase at a breakneck pace, shallow coal resources are increasingly being depleted and the scale and depth of mining operations are growing substantially on a daily basis. Consequently, large deformations, coal bursts and other types of mining hazards in conventional longwall mining are becoming increasingly severe owing to high rock pressures and the intense perturbations induced by mining operations. To address these issues, we propose an innovative longwall method with roof-cutting unloading for coal mining. By using this method to apply cuts in the roof and relieve the rock pressure and by anchoring the roof of the roadway in advance, it was possible to let the goaf areas cave in and allow the formation of roadways. Moreover, this method makes no-pillar mining possible. The control of the mine's ground pressure is one of the most important topics in coal mining research. The ground pressures measured during the application of the proposed method in actual coal operations are reported in this paper. Numerical analysis was carried out to compare the ground pressures and the roof stabilities obtained by the proposed method with those obtained by the conventional longwall mining method. The results confirmed the advantages of the proposed method.