Experimental Study On Paste Filling Technology Of Goaf In Shenfu Mining Area Of Yulin

Shenfu mining area in Yulin,Shaanxi Province is rich in coal resources.In Yuyang area of Yulin,No.3 coal seam is of high quality and thick layer.Before 2008,the small and medium-sized coal mines in this area mostly adopt room pillar mining method.After years of mining,the area of underground goaf increases year by year.Because the room pillar mining recovery rate is only 40%?50%,the coal resources are wasted seriously.With the improvement of mining technology and the state The concept of "green mining" of coal is put forward,and the strip mining is gradually promoted in Yuyang area.Although the strip mining conforms to the current concept of green mining,its resource utilization rate is still not significantly improved.Therefore,in order to improve the recovery rate of strip mining method,based on the current strip mining technology of "mining 12m and reserving 8m" in Yongle coal mine in Yuyang area,this paper analyzes and studies the 3231 working face,and studies the feasibility of recovering and reserving 8m coal pillars with paste filling technology.In this paper,loess is added to the former preparation of aeolian sand paste slurry for research through theoretical calculation By means of laboratory paste experiment and FLAC3D numerical simulation analysis,the change characteristics of bearing capacity of coal rock support system,coal rock paste support system and paste support system in the process of mining,paste filling and coal pillar recovery are studied in depth.The results are as follows:(1)Through theoretical calculation,it is found that the stress of the strip coal pillar of 8m is between 5.62MPa and 6.65MPa,and the minimum compressive strength of the paste filler is 5.44mpa.(2)Under the ratio of cement:aeolian sand:Fly Ash:loess with the mass of 2:4:2:1,the flow characteristics and later strength of ZJ12 group paste slurry made of 77%mass percentage concentration meet the requirements of filling mining.(3)Through FLAC3D simulation analysis,it is found that the stress of the strip coal pillar with 8m reserved is 5.77MPa,and the simulation results are basically consistent with the theoretical calculation;after the simulation of replacing the coal pillar with paste made of ZJ12 group,the simulation results show that the stress of the strip paste is 3.95MPa,which is less than the theoretical calculation value of 5.44MPa,so it can be inferred that the paste made of ZJ12 group is in the permanent state It is feasible to replace coal pillar in Le coal mine.