Formation mechanism and prediction method of water inrush from separated layers within coal seam mining: A case study in the Shilawusu mining area, China

Water inrush form separated layers (WIFSL) is one type of mine water disaster, threatening the safety of coal mines. A thorough understanding of WIFSL formation mechanisms is prerequisite for creating water control measures. In this study, the formation conditions of roof bedding separation, menacing bed separation water and formation conditions of WIFSL were examined. According to the composite beam theory, the traditional criterion for bed separation location is revised. Combining the Winkler foundation beam model, the mechanical model for bed-separation water hazard above the water-flowing fractured zone (WFFZ) was established, and the theoretical discriminant of the first and periodic WIFSL was deduced. In addition, the water inrush coefficient method was used to divide the WIFSL risk. The results of this study show that separation locations are controlled by a combination of lithology, rock thickness, and elastic modulus. The formation of bed separation water is restricted by the separation locations and recharge water source. The formation of WIFSL mainly depends on the strength and thickness of the protective layer, between the bed separation and the WFFZ, and the foundation coefficient of the fractured rock mass in the WFFZ. Taking Shilawusu coal mine, Dongsheng coalfield, Inner Mongolia autonomous region, China as the application examples, the risk of WIFSL within the mining area was predicted and classified. In addition, theoretical analysis and calculation of bed separation locations, foundation coefficient, and periodic inrush distance of WIFSL within the 06A working face were carried out, verifying the accuracy of the theoretical model and prediction method in this study.