Simulation of water resource loss in short-distance coal seams disturbed by repeated mining

Physical simulations and field measurements were performed to study the movement of overlying strata and water conductive fractures (WCF) under conditions of repeated mining in short-distance coal seams. In addition, the feasibility of water resource conservation mining (WRCM) was analyzed in areas disturbed by repeated mining. The results of the simulation showed that the aquiclude remained intact after the mining of Coal Seam 11 (the 1st main seam) in Shigetai coal mine in northwest China. According to the findings, WRCM can be conducted in this area. After the mining of Coal Seam 12 (the 2nd main seam), the WCF in overlying strata above the central section of the mined-out area will gradually compress and close. However, due to the impact of repeated mining in short-distance coal seams, WCF in overlying strata at the edge of the mined-out area are connected to the Quaternary loose aquifer and are not likely to close, resulting in the loss of the water resource. Thus, WRCM in this area would be difficult to conduct. Moreover, field observations showed that the aquifer can likely remain intact after Coal Seam 11 is mined, but the aquifer’s water level will probably not fully recover if Coal Seam 12 is mined. This is consistent with the simulation results. Therefore, appropriate technical mining measures must be taken to conduct WRCM at the 2nd main seam in the shallow-buried short-distance coal seams. These research results can be used as a reference for future WRCM endeavors in the arid and semi-arid regions of northwest China.