Based on the Numerical Simulation Analysis of the Impact of Coal Mining in the Land Conservation Area

As China pays more attention to the protection of water resources, there are overlapping areas between the planned reservoir conservation area and planned coal mine field. In the coal mining process, a water-conducting fracture zone is formed after the roof of the goaf is damaged, and cracks also generated on the surface of the mining area. In order to study the effect of coal mining on the recharge of surface water into the reservoir in the land conservation area, FLAC3D and Visual MODFLOW are used to simulate the development law of water-conducting fracture zone and surface subsidence cracks in the roof of the coal seam after coal mining in the land conservation area of the reservoir. Prediction and analysis on the change of the reservoir recharge capacity after coal mining in the land reserve are conducted. The results show that the maximum growth height of the water-conducting fracture zone in the overlying strata of the goaf after coal mining in the secondary land conservation area of the reservoir is not connected with the surface subsidence fracture. However, coal mining induces partial aquifer drainage in the roof of the coal seam, increasing the amount of surface water flowing to groundwater. Therefore, the maximum drop in the water level of the reservoir is 0.19 m, and the maximum recharge of the reservoir is 52,900 m33/a, accounting for 0.89% of the total recharge. It demonstrates that coal mining in the secondary land conservation area has little effect on the recharge of the reservoir. On the basis of good ecological compensation, water saving and comprehensive utilization of mine water, coal mines need to further carry out research on mitigating the adverse effects of coal mining on the reservoir’s land conservation area.