Study On Rock Covering Activity And Support Pressure Law Of Filling Working Surface Of Luxi Coal Mine

Filling mining is a coal mine green mining technology with the characteristics of good safety,high recovery rate and environmental friendliness.It can effectively solve the problem of "three under"(under buildings,railways and water bodies).Based on the C01 Island filling face of a mine in Luxi,aiming at the problems such as severe mine pressure and urgent evaluation of filling effect,this thesis adopts theoretical analysis,numerical simulation And on-site monitoring,the law of overburden activity and ground pressure behavior in filling mining are studied.The main conclusions are as follows:(1)Based on the elastic foundation beam theory,the rock stratum control mechanical model of filling mining in C01 face is established.Based on the model,the main and secondary influencing factors affecting roof subsidence are explored.The analysis shows that the amount of roof and bottom moving close before filling and the amount of under connected roof are the main factors constituting roof subsidence.(2)Using numerical simulation method,the distribution law of overburden activity and advance bearing pressure of working face under different equivalent mining height is studied.The smaller the equivalent mining height is,the smaller the roof subsidence speed is.When the equivalent mining height is 1m,the roof subsidence speed and basic roof displacement are significantly reduced.When the equivalent mining height increases from 1m to 1.2m,the stress concentration factor increases to 2.15,and the stress accumulation of coal in front of the working face reaches a dangerous state.Therefore,the optimal equivalent mining height is determined to be 1m,and the corresponding filling rate is 89.4%.(3)The measured analysis shows that the maximum surface subsidence is334.2mm,the maximum inclination is 1.2mm/m,and the maximum curvature is0.04mm/m2.The surface deformation of the mine is less than the critical deformation value,and the damage level of surface structures is grade I.after mining,the buildings can be used normally with or without simple maintenance,which proves that the bearing effect of the filling body on the overburden of C01 working face is very good.(4)The inclined abutment pressure of goaf is saddle shaped in the early stage of mining.With the end of load transfer process and the stability of filling body roof connection,the distribution of abutment pressure is approximately convex parabola.After 18 days,the stress value of the filling body reached 22.6MPa and remained stable.The strike of the working face is ahead of the working face,the stress rise area of the working face is 0～15m,the peak stress is about 39 Mpa,the influence range is0～50m in front of the working face,and the stress concentration factor is about 1.9.Filling mining effectively reduces the stress accumulation,and the filling effect of C01 working face is good.