Study on law of groundwater resources leakage under high intensity repeated mining

The focus of coal resources development in China has shifted to the west, but the ecological environment in the western region is fragile and groundwater resources are precious. The contradiction between high-intensity coal mining and groundwater and ecological environment protection has become increasingly serious. In recent years, most mining areas in the west have gradually developed and mined the lower coal seams. In view of the lack of research on the influence of repeated mining in multi-layer coal seams on groundwater resources and other issues, field measurement and numerical simulation have been used to measure and calculate the development height of water flowing fractured zone by taking the No.42202 working face of Bultai Coal Mine in Shendong Coal Mine Area as the research object. The results show that the maximum development height of the water conducting fracture zone after the mining of the 42nd coal seam reaches 160 m above the roof, which connects the aquifer of Yan’an formation and Zhiluo formation, but does not connect the aquifer of Cretaceous Zhidan group; based on the monitoring results of the water conducting fracture zone, the water inflow of No.42202 working face is estimated to be 63 m3/h by FEFLOW numerical simulation method, which is close to the actual water inflow (55 m3/h), further showing that the water inflow of working face mainly comes from the aquifer of Yan’an formation and Zhiluo formation; after the mining of No.42202 working face, the water level of Yan’an formation aquifer decreased by 57.3 m, and Zhiluo formation aquifer decreased by 11.9 m, and the water level of Cretaceous Zhidan group aquifer basically remained stable. It can be seen that the coal seam has the greatest disturbance to the Yan’an formation aquifer, followed by Zhiluo formation aquifer, and has no effect on Cretaceous Zhidan group aquifer; The water flowing fractured zone of coal seam mining is the main channel of groundwater resources leakage, and its development height determines the degree of disturbance of coal mining on aquifers. Restraining the development of roof water conducting fractured zone after coal mining is the key point to realize water conservation coal mining in large western mining area, especially with the deep development of coal and rock resources in the west, the overburden fracture law and its multi field coupling characteristics after multi-layer coal seam mining. It is an important research direction in the future to study the evolution law of water diversion fracture zone. The research results improve the water conservation theory of multi seam mining, and provide a support for the green development of coal resources in western China.