Failure evolution of collapse column area in deep mine based on numerical calculation and microseismic monitoring

With the depletion of China's coal resources and the increase in mining depth, high ground stress and high confined water cause frequent accidents. Taking the 12123 working face of Pan'er coal mine in Huainan Coalfield as the background, this study discussed the water disaster caused by the connection of water channels induced by mining disturbance with the collapse column. The catastrophic process of water inrush induced by the collapse column was studied through the numerical simulation of stress field and failure evolution of acoustic emission (AE) interpretation. The grouting method of plugging and reinforcement was introduced, and the effect was evaluated and analyzed. Results showed that the inrush formation of fracture channels was related to the coupling of the physical and mechanical properties of the collapse column and the surrounding rock, mining stress disturbance, and other complex factors. Obvious spatiotemporal effects were observed during structure activation, fracture initiation, fracture expansion, and channel formation of water disaster. The surrounding rock of the collapse column was deformed and split under stress and high water pressure. When the mining face was near the collapse column, the number of AE signals increased sharply from its adjacent top region. After passing through the threatening area, the water channels evolved from the structural bottom to top and produced water gushing. After optimized grouting reinforcement was carried out in the surrounding rock area, microseismic monitoring revealed that the failure depth of the floor in the adjacent area was generally large. The events showed obvious deflection and detour in the collapse column. Few microseismic events occurred on top of the collapse column and its boundary rock, and the spatial distribution of microseismic signals was significantly different from that before grouting, which proved the effectiveness of the grouting method. This study will be conducive to the prevention and control of mine water disasters and promote the wide application of effective grouting technology in mining engineering.