Risk Evaluation and Leakage Mechanism on Runoff in Coal Mining Area—A Case Study in Jinjie Coal Mine of Tuwei River

According to the aims of the runoff protection in coal mining area, taking Jinjie coal mine as an example, the risk zonation and mechanism of runoff leakage were carried out based on the dimen-sionless multi-factor information fusion technique. Based on the analysis of field exploration and borehole data, four key factors affecting the runoff leakage from the roof were identified, which included the deposition features of aquifer in Sala Wusu Group, the distribution of overburden rock and soil mass, effective thickness of aquiclude layer and the height of water flow cracking zone. The evaluation criterion was whether the development height of the water flow cracking zone reaches or exceeds the bottom plate of the sandy phreatic aquifer and even penetrates the surface ground, which results in the complete or partial leakage of the phreatic water. According the evaluation criterion, the influence of coal mining disturbance on runoff leakage was divided into three zones: zone of seriously runoff leakage, zone of general runoff leakage and zone of slight runoff leakage. Furthermore, the influence mechanism of different zones in coal mining also been discussed preliminarily, which included drainage Sarawusu aquifer, groundwater leakage in Sarawusu aquifer, water level fluctuation in Sarawusu aquifer and so on. Finally, classification pattern diagram was drawn.