Quantitative characterization of the disturbance of groundwater system in typical coal seam mining in contiguous area of Inner Mongolia and Shaanxi

High-intensity mining of coal mines in ecologically fragile areas disturbs the groundwater system and causes water resources loss. The typical shallow and deep mining mines in the middle section of the Yellow River basin are selected as the research objects, and the development height of the water-conducting fracture zone in the shallow composite coal seam mining and the deep single coal seam mining is comprehensively determined by using the theoretical analysis, numerical simulation of overburden damage and the underground measurement, and the comparison with surrounding mines with similar conditions. According to the spatial location relationship between the water-conducting fracture zone and the main roof aquifer/aquiclude, the water filling model of Zhiluo Formation - Zhidan Group aquifer in shallow coal seam mining and that of Zhiluo Formation aquifer in deep coal seam mining are divided; By generalizing the groundwater flow system of different aquifer water filling modes, the three-dimensional unsteady flow mathematical model of groundwater in typical coal seam mining is constructed, and the numerical model of groundwater flow in two working conditions is established by using Visual Modflow software. The quantitative prediction of groundwater flow field and water resource loss in the mining of the continuous working face is carried out, and the results show that the groundwater from Zhidan Group and Zhiluo Formation aquifers in the disturbed aquifer is converging towards the goaf at the same time, the flow field also gradually recovers with the formation of the secondary stable structure of the roof after mining. Around the goaf, the groundwater flow field shows a local high hydraulic gradient phenomenon; In addition, the average annual water loss of the two coal mining conditions in the continuous period is more than 2 million m³ and 7.3 million m³ respectively. The research results provide a reference for the advanced fine control of regional water resources loss and the utilization of mine water resources.