| This paper takes the extra-thick composite roof roadway of No.8+9 coal seam in Duanwang Mine as the research object,and develops the composite roof thickness 10.07 m for the large deformation of the roadway under the original support scheme,the serious separation of the roof,and even the overall collapse of the anchorage zone.The research on the control mechanism and technology of the extra-thick composite roof roadway has achieved the following main results:1)Establishing a mechanical model to qualitatively study the main factors affecting the separation of the composite roof roadway.Combined with the actuality of the 8+9 coal seam,the main factors affecting the deformation instability of the 8+9 coal seam extra-thick composite roof are revealed: the roadway span 4700 mm,the pretightening force of the bolt is only 10 kN,and the weak rock mass is within 10 m of the roof.The thickness of the single layer is less than 1.5m.Under the vertical stress and horizontal stress,the deformation of the roof is unstable.2)The solution model of the natural balance arch of the 8+9 coal seam extra-thick composite roof is established.The damage height of the roof of the extra-thick composite roof roadway is calculated to be 4912 mm,and the damage range of the two gangs is 1900 mm.The pre-tightening force of the bolt can effectively control the separation of the surrounding rock of the shallow thick composite roof,but the control effect on the deep surrounding rock outside the anchorage zone is weak.3)Establishing the FLAC3 D numerical simulation model,and analyzing the influence of the length of the supporting body,the inclination angle of the supporting body and the pre-tightening force of the anchoring cable on the amount of thickening of the thick composite roof,and determining the support of each supporting body.Reasonable length: 2600 mm roof bolt,2200 mm anchor bolt,8000 mm anchor cable,the inclination angle of the support body is selected: the anchor bolts of the top plate and the anchor cable are inclined by 75°,and the top corner anchor of the gang is inclined by 25°.Installation,and at the same time clarify that within the allowable stress range of the anchor cable,the pre-tightening force should be increased as much as possible.4)Determine a reasonable support scheme,the distance between the anchors is 800mm×1000mm,the length of the roof bolts is increased to 2600 mm,the length of the roof anchor cable is increased to 8000 mm,the length of the bolts of the gang is increased to 2200 mm,the anchors at the two corners of the roof,The anchor cable is inclined at 75°,and the top corner anchor is tilted by 25°.The industrial test is carried out on the 090507 working surface.The maximum sinking amount of the roof during the excavation is 57 mm,and the convergence of the gang is 64 mm.During the mining period,When the working surface is 70 meters away,the convergence speed of the top plate and the two gangs is less than 8mm/d;when the working surface is advanced within 70 m of the observation section,the convergence speed of the top plate and the two gangs is greater than 8mm/d,especially when testing the section When the peak area of the pre-stress is approached,the convergence convergence speed suddenly increases to 20mm/d;the maximum sinking amount of the top plate is 73 mm,and the convergence of the two sets is 79 mm,which can meet the production demand.The paper has a total of 40 pictures,18 tables,and 86 references. |
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