Large-row Support Technology Research Of No.3 Coal Seam Roadway In Youzhong Mine

In this paper,the coal mining road of No.3 main mining coal seam of Youzhong Mine is taken as the research object.For the roadway,the roadway speed is slow due to the unclear mechanism,the lack of supporting parameters and the excessive support density.Excavation and other engineering problems,and the research on the support mechanism and control technology of the rectangular section coal roadway with average coal seam thickness of 2.05m,coal seam average inclination angle below 10° and average burial depth of 225m,especially in the determination of bolt spacing The selection of parameters has obtained useful conclusions,and the main results are as follows:(1)Combining the composition of the complete anchor system,the defects of the existing support system of No.3 coal roadway in Youzhong Mine are analyzed,which is mainly manifested in the absence of butterfly tray,self-aligning ball cushion and anti-friction washer in bolt support;In the cable support system,the center of the ball is absent,and the result is that the material used for the support material is better,but the support effect is not good.(2)Using the in-situ bolt pull test,the test found that the critical anchor length of the top anchor should be about 1100mm.It is found that by applying the pipe joint anchor in the free section of the bolt,the free section anchor hole can be prevented.Collapse,improving the engineering practice of reducing the preload of the bolt.(3)The relationship between the pre-tightening torque of the bolts and the pre-tightening force of the bolts was tested.The pre-tightening torque and pre-tightening of the roof of the No.3 coal seam roadway of Youzhong Mine and the two sets of anchors were not adopted.The conversion efficiency of the force is 79.5%and 74%of the wear-reducing washer respectively.At the same time,the self-aligning ball cushion generally improves the bearing capacity by more than 50%by improving the spatial position of the anchor cable.(4)Using Flac3D numerical simulation software,the mechanism of bolt support is discussed,and the influencing factors in large row anchor support are analyzed,from preload,bolt length,anchor length and bolt angle and spacing.The law of stress distribution range and effective bearing area in anchors is studied in five aspects,and the control scheme of 1100mm large inter-row anchor,anchor cable and Gebin network coupling surrounding rock is obtained.(5)The 900mm row spacing is adjusted to 1100mm,the length of the anchor rod body is increased to 2200mm,and the pre-tightening force of the top plate is not less than 300 N·m,and the angle of the top and bottom corner angle bolts of the top plate is changed to 20.The diameter of the drilling hole is changed.It is 27mm;the spacing of the roof anchor cable is changed to 1800mm,the row spacing is changed to 3300mm,the initial tension is not less than 80-120kN,and the angle is changed to 20.The row spacing between the bolts is expanded to 1100×1100mm,and the diameter is changed to 18mm,increase the length of the bolt to 2200mm,increase the pre-tightening force to 250 N·m,and change the diameter of the hole to 27mm.The research support scheme was applied in the transportation of the 30104 working face of Youzhong Mine.The on-site mine pressure monitoring showed that the average subsidence of the roof of the roadway was 47.5mm,and the average moving amount of the gang was 54.5mm,which could meet the roadway during the mining.Normal use requirements.During the mining,the maximum amount of movement of the roadway is 69mm,and the maximum sinking amount of the top floor is 74mm.The tunneling speed increased from 200m/month to 280m/month.The research results of the thesis can provide a good reference for coal roadway support under similar engineering geological conditions.