A new understanding of the mechanism controlling water inflow into mines based on the stratigraphic distribution beneath major aquifers through a case study of the Yijun Formation in the Binchang mining area, Shaanxi Province, China

Abstract

The Binchang mining area is located in the southern Ordos Basin. The water inflow in mines and working faces is considerable due to the Jurassic aquifers and thick Cretaceous aquifer above the coal seams. The water inflow into mines caused by the thick Cretaceous aquifer is considerable, and the mechanism controlling the mine water inflow is still unknown. This case study is based on the mine water inflowand the thickness of the Yijun Formation in the Binchang mining area and reveals a significant correlation between the mine water inflow and the overlying major aquifers. A qualitative analysis was performed to study the relationship between the sedimentary facies and the distribution of mine water inflow in the Tingnan Coal Mine. A random forest (RF) model was applied to identify the key factors affecting the water inflow at working faces. The analysis results showed that in addition to the aquifer characteristics, the water inflow at working faces is negatively correlated with the sedimentary thickness of the Yijun Formation, and the thickness has the greatest influence on the distribution of water inflow. Furthermore, the Yijun Formation is not only an important aquifuge but also determines the bottom morphology of the Luohe Formation, which is an important aquifer. The area with a thin Yijun Formation is also the catchment area at the bottom of the Luohe Formation. This case study first reveals that the underlying strata have an important influence on the sedimentary environment and water abundance of the upper aquifer. The relationships and findings in this case study can provide helpful references for the prevention and control of mine water in similar mining areas.