| Taking JinJie coal mine as an example in northwestern China with arid climate, based on remote sensing interpretation and DEM, Divide the study area into five groundwater subsystems, clarify the roof groundwater circulation changes before and after the mining. Based on the theory of upper three zones, the three-dimensional water-filled space of roof coal seam mining damaged is determined, using the Probability Integration Method and FLAC3D numerical simulation, and verification by drilling.Based on the dynamic variation of coal seam roof groundwater in the process of working face promoting, the hydraulic conductivity of aquifuge roof and the change mechanism of closing properties are revealed. The paper gives the concept of variation of hydraulic properties of aquifuge and variation conditions. Besides, variation patten of aquifuge hydraulic properties of coal seam roof in the process of working face of Jinjie mining promoting is summed up. On the same premise, coal mining area and roof aquifer, aquifuge four composite types are divided. Changes in circulation channels of groundwater and effects on the groundwater system input, output, storage performance and its hydrogeological parameters before and after mining are both researched. Besides, the concept of mining variation of water cycle induced by mining and its regulation are put forwarded; based on these ecological environment hydrogeological problems caused by coal mining, concept of groundwater environmental capacity of mining area and its evaluation index are proposed. Based on the method of7Q10and water balance, the limit threshold of groundwater environmental capacity in mining area is determined. According to the evaluation results of water disaster danger obtained by the three-map overlaying method and the simulation with Visual Modflow, the new idea of coal mining and water holding is put forward. |
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