Study On The Overlying Rock Movement And Underground Pressure Law In The 8# Coal Seam Of Shenzhou Coal Industry

Working face 8102 of Shenzhou coal industry is the first working face of 8# coal seam in the mining area which roof is mostly hard rock.The working face adopts deep hole blasting roof to prevent the roof from hanging and high pressure strength.Moreover,several measuring stations are arranged at the working face to monitor the deformation of surrounding rock.According to the geological conditions of the working face,the model is established,and combined with the field monitoring data,the overburden structure,movement law and ground pressure law of 8102 working face are studied and analyzed.According to the geological data of Shenzhou coal industry and the data of mechanical parameters measured by on-site drilling and coring,the key layers of 8# coal seam are medium grained sandstone and limestone by using the theoretical analysis of key layers.When the coal seam roof is not treated,the two ends of the coal seam roof can be calculated by the fixed support structure at both ends according to the beam structure.At this time,the direct roof collapse step is 29.99 m and the basic roof failure step is 41.79 m.After the deep hole presplitting blasting of the roof,the roof structure changes,and the blasting end of the rock stratum changes from fixed support structure to simple support structure.After the mechanical analysis of the structure,it is obtained that the direct roof collapse step after roof cutting is24.49 m and the basic roof failure step is 34.12 m.The overburden collapse zone,fracture zone and bending subsidence zone are analyzed according to the three zone empirical formula.Combined with the discrete element 3DEC numerical simulation method,the overburden collapse shape under different advancing distances of the working face is asymmetrically distributed,and the roof collapse center is in the middle of the goaf and close to the goaf.When the working face advances for 30 m,it can be judged as the initial pressure.The failure zone and sliding zone of rock joints are periodic failure.The failure angle of overburden is 45° with the advancing direction of the working face.The failure range of rock joint is concentrated within 5 m in front of the coal wall,and the collapsed rock in the goaf lags behind the working face for 40 m,which can be basically compacted.According to the simulation of finite difference software FLAC3 D,the vertical stress distribution of the basic roof is semi elliptical,and the vertical pressure in front of the working face is slightly greater than the lateral stress distribution of the goaf.The peak value of the advance bearing pressure of the coal seam is5.4～10.6 m in front of the coal wall of the working face,with a distribution range of14.98～24.88 MPa,and the lateral bearing pressure is 13.17～15.30 MPa,which is 1.21～1.32 times of the original rock stress.The failure depth of medium grained sandstone in front of coal wall reaches 25 m.The coal wall needs advance support.Combined with the field data,the author uses the analysis of variance to determine that the spacing of 10 measuring points is more appropriate,and determines the initial pressure level.It is determined that the initial pressure step is 30 m,the average periodic pressure step is 18.4 m.It is verified in combination with the monitoring data of the working face.The average dynamic load coefficient of the support is 1.24,and the compressive strength is small.Combined with the monitoring data of the measuring station in the return air roadway and transportation roadway,it can be seen that with the advancement of the working face,the measuring station gradually approaches the area affected by the bearing pressure.Stress of anchor rod and anchor cable shows an increasing trend,and the roof separation of the roadway is small.It can be seen that the working face has little impact on the transportation roadway and return air roadway.The roadway support meets the needs of the working face.The conclusions in this paper provide a theoretical analysis for the follow-up face layout and mining work of Shenzhou coal 8# seam,and have a certain guiding value for the analysis of similar mines.