Hydrogeological characteristics and progress of water-preserving coal mining of northern Shaanxi Coalfield

Green mining has become the most basic requirement for mine construction.As an important part of the green mining technology system,water-preserving coal mining focuses on solving the problems of groundwater resources and ecological environment protection in mining areas.By summarizing the hydrogeological characteristics of karst groundwater of northern Shaonxi Coalfield,and clarifying the relationship between coal seam mining and limestone karst water,and the achievements made in the research of water-preserved coal mining of northern Shaonxi Coalfield were generally reviewed.The results show that the karst groundwater level of northern Shaanxi Coalfield has a downward trend as a whole.The groundwater table has dropped by about 18.5 m at a rate of 0.64 m/a in the past 30 years.The eastern part of Chenghe Mining Area and the No.5 coal seam of Hancheng mining area are both below the karst water level,and coal mining is seriously threatened by karst water.The water inrush mechanism of the No.5 coal seam have two types:① The effective water barrier of the floor is thicker,and the fault cuts the aluminum between K2 (Quartz sandstone and limestone water-bearing rock group of the Upper Carboniferous Taiyuan Formation) and the second member of Fengfeng Formation limestone aquifer.In the mudstone water-resistant layer,the water pressure failure and the mining floor failure area are connected to each other,resulting in water inrush; ②The containment layer is relatively thin,and the damage area caused by the high-pressure water head is connected to the mining floor failure area，which leads to water inrush.The K2 and below water-resistant layer shall be fully grouted to produce an effective aquifer of 25～30 m,which can realize water-preserved coal mining in the area.The water-preserving coal mining technology on the confined water of of northern Shaanxi Coalfield has certain reference significance in similar areas.