Evaluation of Water Inrush Vulnerability and Feasibility Analysis of Mining Under Rivers: A Case Study Involving the Jinjie Coal Mine in China

The shallow groundwater of the Quaternary Salawusu Formation in China is distributed widely in the arid and semi-arid areas of northern Shaanxi and is an essential component of water supply and ecosystem maintenance there. To safely exploit the coal resources and protect the water resources, it is important to understand the impact of local high-intensity coal mining on such shallow groundwater. We used the "three maps-two predictions" method, the theory of equivalent mining height, and numerical simulations to evaluate the water inrush conditions for the 3-1 coal seam and to analyze the feasibility of backfill mining under the Qingcaojiegou and Hezegou Rivers. The results for the Jinjie coal mine showed that: part of the Quaternary porous phreatic aquifer and most of the J(2)z weathered-bedrock pore-fissure confined aquifer are high-risk areas in the connectivity zoning map; there are large areas of strong or relatively strong water-abundant areas in the 3-1 coal seam roof, and; large areas in the southwest, northwest, and northeast parts of the coalfield are in high- and low-risk areas and face a serious threat of roof water inrush. Overall, it should be feasible to mine under these rivers, using backfill mining to effectively reduce the height of the water-flowing fractured zone and amount of surface subsidence.