Risk assessment of water inrush from aquifers underlying the Qiuji coal mine in China

With the continuous increase in mining depth, mine-confined water accidents occur more frequently, which seriously threaten the safety of employees. Taking Qiuji coal mine in eastern China as an example, this paper introduces a novel method for evaluating high confined water hazard in coal seam floor. The no. 11 coal seam in Qiuji coal mine has been threatened by the underlying karst water. The water pressure of the aquifer, the aquiclude thickness, the coal seam depth and thickness, the brittle-rock thickness of the coal seam floor, and the geological structure are the important factors to control the floor water inrush. The risk of water inrush from the floor of 11 coal seam in Qiuji coal mine was evaluated using the improved analytic hierarchy process vulnerability index (IAHP-VI) method. The IAHP-VI method used the improved analytic hierarchy process to derive the weights of six factors and establish the vulnerability index model. Consequently, through data processing and spatial superposition function of GIS, the zoning map of risk assessment for high confined water hazard on the floor of the study area was obtained. The IAHP-VI method was compared to traditional water inrush coefficient method, which demonstrated the advantages of IAHP-VI method. The IAHP-VI method was more suitable for risk assessment of floor water inrush under complex geological conditions.