Study On The Water Separating Capacity Of The Fengfeng Group When Mining The Lower Coal Mine

The under-group coal seams of Zhao Zhuang coal mine is about to enter the mining stage.Because the mean distance between the floor of coal seam and the top interface of Ordovician limestone is only 22.6 m,the exploitation of the under-group coal seams faces the threat of water bursting from the bottom of the Ordovician limestone water.A large number of research data show that there is a water-resisting layer in Ordovician fengfeng group,and it can be the key water-resisting layer when mining under-group coal seams.Therefore,this paper takes Ordovician limestone fengfeng group as the research object.Based on the water pressure test of the water-resisting property of top fengfeng group limestone,it is determined that the effective barrier thickness of the top fengfeng group is 30 m.Furthermore,according to the actual data of the damaged depth of the bottom mine plate which is closed to Zhaozhuang Mine or has similar geological conditions,artificial neural network method is used to study the fracture depth of under-group coal seams.After making a simulation calculation,the maximum seam floor ' s fracture depth of under-group coal seams is 17.63 m.In combination with the water-resisting layers of taiyuan group limestone which is between the under-group coal seams and the top of Ordovician fengfeng group,the thickness of Benxi group limestone and water-resisting layers of Ordovician fengfeng group,and the fracture depth of under-group coal seams;it is concluded that the effective thickness of water-resisting in the coal seam is 22-49 m.According to the results of calculation,we draw the space layout map of effective water-resisting layer.Depend on the space layout map and exploratory Ordovician limestone water level data,the water bursting coefficient of each borehole in the whole region is calculated,which reveals that the scope of water bursting coefficient is 0.0026-0.1834MPa/m,and the water inrush danger zone is evaluated.On the basis of the above research work,this paper puts forward the coal floor grouting reinforcement scheme of under-group coal seams.In accordance with the research results,it provides a powerful reference for the mining of Zhao Zhuang coal mine under-group coal seams.