Research On Support Technology Of Mining Roadway In Extra-thick Coal Seam Of Soft Rock Roof

Safety production of extra-thick coal seam mine is one of the primary concerns in coal mining.Due to the thick layer of coal seams,there is a dirt band in the middle of the coal seam,the strength about the coal-rock mass is low and the joints are developed.The roof of the mining roadway is extra-thick coal seam.The thickness of the roadway is limited to more than ten meters.The roadway support is limited by the extra-thick coal seam condition of the soft rock roof.The cable fixed position cannot be realized in the hard rock layer.The support of the extra-thick coal seam roadway lacks effective control.Solving the problem of roadway support and designed roadway support schemes,which are the guarantee for safe mining of extra-thick coal seams.No.9 extra-thick coal seam in LianSheng Coal Mine as research project background,From the physical and mechanical properties test of coal sample,stress analysis of roadway surrounding rock,the viscoelastic deformation of surrounding rock,the variation of supporting structure parameters,additional stress field generated by anchor and cable,and the simulation experiment of engineering support To analyze stability about the 9102 mining roadway in LianSheng Coal Mine,exploring the influence of supporting structure on the stability of extra-thick coal seam roadway.Using theoretical calculations to design the support scheme and perform numerical simulation verify.The project site roadway support provides scientific guidance to solve the stability problem of extra-thick coal seam roadway,and also has certain reference value for other roadway support in extra-thick coal seam of soft rock roof.The main research contents and results are as follows:?1?The laboratory test analysis shows that the LianSheng No.9 extra-thick coal is rich joints.The uniaxial compression experimental rock failure mode is mainly shear failure,accompanied by splitting damage,the coal sample residue is broken after crushing,the strength of coal rock is low,Coal sample classification is VIa,it belongs to the weak broken rock mass.?2?The elastic theory plane problem is used to analyze the stress distribution around the circular roadway,which shows that the lateral pressure coefficient of the roadway has a direct influence on the stress distribution around the roadway.The mathematical model is used to calculate the tangential stress distribution around the rectangular roadway under different axial ratios and lateral pressure coefficients,Provide a theoretical basis for the design of the roadway.?3?According to the viscoelastic deformation of the roadway,the viscoelastic deformation characteristics of the surrounding rock of the roadway are analyzed by the rheological curve of the roadway.The surrounding rock failure of the roadway is divided into three types.The viscoelastic force and deformation of the rock are analyzed by the Burgers rheological model.?4?The FLAC^3D software is used to analyze the stress and deformation around the roadway.The results show that the tensile stress and shear stress of the roof of the roadway are tensile and shear failure.The two sides are mainly subjected to shear failure caused by vertical compressive stress.In the design of roadway support,eliminating the tensile stress of the roof and improving the bearing capacity of the two roadways are the difficulties and key points of roadway support.?5?The design of double-bearing support system for anchor and cable,which is mainly based on the determination of reasonable anchors and cable support schemes and support parameters.The orthogonal test is used to analyze the control effect of anchor and cable support parameters on the surrounding rock of the roadway.The results show that the length and spacing of anchor have significant effects on surrounding rock control of extra-thick coal seam roadway.Cable spacing,pre-tightening force and other factors are slightly smaller.?6?Aiming at the support problem of extra-thick coal seam roadway,using elastic theory plane problem,roadway viscoelastic deformation analysis,simulation analysis of roadway stress change and plastic zone damage range,orthogonal test to determine the significance of support parameters,etc.Finally,proposed anchor+cable+W steel belt+metal mesh joint support form.The surrounding rock deformation is controlled by the double bearing layer structure of the anchor-cable.?7?According to the design support scheme of the 9102 transport roadway,the simulation software is used to verify the control effect of the support scheme on the surrounding rock of the roadway.The results show that the optimized support scheme effectively controls the deformation of the surrounding rock.The anchor and cable structure in the middle of the roadway are stable.Which are the key to the surrounding rock control of the roadway.