Risk Assessment On Water Inrush Of No.6 Coalseam From Floor In Deep Mining Area Of Yangzhuang Coalmine

China is a large coal producing country,of which 90%of the total output belongs to mine mining.However,due to the complex geological and hydrogeological conditions of coal mines,the coal reserves threatened by water disasters account for about 27%.North China coalfield,as the main coal production base in China,due to the fact that mining the deep lower coal seam is threated by floor strong aquifer in coal bearing strata.Yangzhuang coal mine belongs to north China coalfield,the 6coal seam mining threated by Carboniferous Taiyuan formation and Middle Ordovician limestone aquifer.And ?1??2 mining area belong to deep mining area,the water pressure increases,and the water inrush degree increases.Therefore,it is of great realistic significance to predict the risk of water inrush from the 6 coal seam floor.Based on collecting geological and hydrogeological data of mining area,the physical,geological and hydrogeological conditions,water abundance of limestone in Taiyuan formation,lithological association,thickness,rock mass structure characteristics and types of the study area are analyzed.And the paper analyzes the floor impermeability in ?1??2 mining area.The results show that the impermeability is better.Through the hydraulic fracturing method to test the water resistance of the 6 coal seam floor,it can be concluded that the permeability of the thin rock mass is high,the water resistance is weak,and the permeability of the thick rock mass is lower,and the water resistance is better.Through the analysis on the burial depth of Taiyuan formation limestone,the variation regulation and water table features of unit inflow in study area,the water abundance level of Taiyuan group 1?4 group limestone aquifer in study area is weak to strong water abundance,and with the increasing burial depth of limestone aquifer,rock permeability decreases gradually.Failure rule of the 6 coal seam floor is simulated under mining conditions by applying numerical simulation technology(FLAC3D),and predict the maximum floor-broken depth.By using the comprehensive evaluation method of multivariate information,the paper selects 6 indicators,namely the water abundance,water pressure of the limestone aquifer,bottom sandstone rate,effective aquifuge thickness,the fractal dimension of fracture and fault density for the risk evaluation of water inrush from the 6 coal seam floor,compares and analyzes the results with the evaluation results of the water inrush coefficient method,it is concluded that the comprehensive evaluation method of multivariate information is more suitable for predicting the risk of water inrush from coal seam floor.