Analysis of overburden failure development height in high-intensity mining area in Western China

Water-conducting fracture zone is the main channel of water damage in coal seam roof. It is an important task to accurately predict and calculate its development height to ensure the safety of mine production. Based on the measured data, the failure types, failure relations and the development characteristics of water-conducting fracture zone of mining overburden in the western high-intensity mining area are revealed by theoretical analysis and similar simulation. The results show that the overlying rock failure type is serious damage type under the condition of high strength mining of thin bedrock thick coal seam. There are only “two zones” in the mining overlying rock, there is no bending zone with certain water insulation after rock failure above the goaf, and the water-conducting fracture zone leads to the surface, causing serious damage to the surface. The overlying rock migrates in the form of assemblage key layers. In the process of mining, the combination of key layers produces shear fracture at both ends of the rock layer by sliding and destabilizing, resulting in the shear fracture of the overburden bedrock and loose layer, and the formation of stepped cracks on the surface. The spacing of the measured step fracture along the advancing direction of the working face is consistent with the pressure step of the downhole cycle. Considering the critical factors such as the mining thickness of overlying rock and the thickness of bedrock, a formula for predicting the development height of water-conducting fracture zone in high-intensity mining is proposed. The reliability of the formula has been verified by field measurement and similar material simulation results. The research results have certain guiding significance for the safe mining of coal mine in Shendong Mining Area.