Water inflow characteristics of coal seam mining aquifer in Yushen mining area, China

The Yushen mining area is located in the arid and semi-arid regions of western China. Coal mining activities in this mining area face the challenges of water resource pollution. In this study, in order to study the water inflow law of aquifer caused by coal mining activities, the overlying strata of the mining seam are divided into four aquifer groups according to the geological and hydrogeological characteristics in Yushen mining area. Three categories of aquifer water inflow are proposed by considering the depth of the mining coal seam: the water-conducting fractures formed by coal mining disturbance, the distribution of aquiclude, and the water inflow characteristics, i.e., (1) shallow seam—damaged aquifuge—direct water inflow (SDD), (2) medium seam—single aquifuge—longitudinal water inflow (MSL), and (3) deeply buried seam—two aquifuges—small water inflow (DTS). Then, the aquifer water loss numerical models of three kinds of actual mines in the study area are established by numerical simulation. The simulation results show that due to the water-conducting fractures that developed in the Sandy aquifers, the top aquifer of the mining face is dry. Although the water-conducting fractures only extend into the bedrock aquifers, the groundwater flow of the Sandy porous aquifer is basically unchanged due to the protection by the key soil layers and the secondary mudstone aquifuges for the DTS group. In the MSL group, in which the water-conducting fractures are extend into the interior of the bedrock aquifer as a result of stratified mining of the coal seam, the groundwater flow of the sandy aquifer little change. However, when the full height of the coal seam was mined, it will cause a large influence on the sandy aquifers because the water-conducting fractures have entered the bottom of the weathered bedrock aquifer. This paper quantitatively analyzes the impact of coal mining on aquifer groundwater and provides basic data for coal mining and water resources protection in western China.