Study On Water Bursting Index System Of Thick Loose Layer In Qidong Mining Area Based On Multi-field Coupling

When mining coal under an aquifer,in order to ensure mining safety,the method of leaving waterproof coal pillars or draining the roof aquifer is mainly adopted.Due to the different hydrogeological conditions and coal seam occurrence conditions in each mining area different problems are encountered in the mining process under the aquifer.Coalfields in the eastern part of my country are mostly concealed.The coal seam is covered with 130-500m thick loose layer deposits.At the bottom of the loose layer,there are often moderate to strong water-rich confined aquifers.In the process of mining near-thick loose aquifers,water inrush often occurs in the working face under the combined action of water pressure and ore pressure.Establishing a water inrush index system has important theoretical significance and practical value for preventing such water inrush.Taking the 7131 working face of the third mining area in Qidong Coal Mine as an example,on the basis of collecting data on the exploration,production,and replenishment phases of each mining area in Qidong Coal Mine,as well as data on adjacent mines,mathematical statistics,data analysis,prediction,and numerical values are used.The method of simulation is combined to conduct a comprehensive study on the destruction characteristics of the overlying rock mass under the thick and loose aquifer directly covering the third coal mining area in Qidong Coal Mine,and to establish the water inrush index system of the coal mining roof in the third mining area of Qidong Coal Mine.The risk of water inrush from loose aquifer in 7131 working face(block III)was evaluated.The research results are as follows:1)The roof of the No.71 coal seam in the West Third Mining Area is mostly of the old roof type.The lithology of the roof rock layer and the overlying rock layer is mainly soft rock-medium hard rock.Based on lithological parameters and geological and hydrological data,a thick and loose water cut is established The evaluation index system for the risk of water inrush from the mining roof directly under the seam.2)Using the hydrogeological data of the working face that has been recovered in Qidong Coal Mine,construct a multi-dimensional coal seam roof water forecast statistical analysis model that integrates the in-situ stress index system,aquifer water rich index system and coal seam roof water barrier performance index system.BP neural network numerical analysis method is used to predict the water inrush from the roof of 7131 working face(block III).The prediction results show that the water inrush from the roof of the 7131 working face(block Ⅲ)is 187.5m3/h,and the risk of water inrush from the loose aquifer on the roof is low,which is consistent with the actual recovery results.The model has high predictive value.3)FLAC3D software was used to analyze the coupling of fracture field-stress field-seepage field for the risk of water inrush from the mining roof directly under the thick loose aquifer.The research results are:7131 working face simulated failure height of 58.5m and There is an effective water-proof rock interval of 24.39m between the two.There is no strong infiltration zone in the confined water.The "four-contained" water inrush in the 7131 working face is less likely,and the simulation is consistent with the actual production results.Figure 19 table 19 reference 64...