Rapid Driving Support Technology For High Stress Coal Roadway Driving And Bolting Integration In Chengjiao Mine

With the reduction of shallow carbon resources,the mining depth of suburban coal mine is increasing,and the maximum mining depth has exceeded 900m.Deep mining has the characteristics of high pressure,high temperature,strong mining disturbance and so on,which results in serious deformation of deep roadway.Rapid excavation and stable support of high stress coal roadway in deep mine is an important problem restricting the safe and efficient production of coal mine.Based on the engineering background of the West Wing return air roadway of the second level in Chengjiao Coal Mine,this paper comprehensively uses the methods of in-situ detection,experimental test,theoretical analysis,numerical simulation and field test,focusing on the rapid excavation technology of high stress coal roadway driving and bolting,and mainly obtains the following research results:(1)The physical parameters of coal and rock were obtained by laboratory tests of coal and rock mineral composition and mechanical properties in the West Wing of Chengjiao Coal Mine.The distribution range of the surrounding rock cracks was detected by field drilling,and the development characteristics of the surrounding rock fractures were revealed.By means of theoretical analysis and numerical simulation,five different tunnel cross-section shapes are compared comprehensively considering stress distribution,utilization ratio of roadway cross-section and difficulty degree of tunneling.The optimal width height ratio of roadway section is1.5,and the net size of roadway cross-section is 4.8 m×3.2 m.(2)The surrounding rock support structure model of high stress coal roadway is established.The stress distribution and deformation failure characteristics of roadway surrounding rock with different cross-section shapes are numerically simulated by FLAC^3D software.The stress distribution and deformation law of surrounding rock formed by different prestressed anchors(cables)are compared and analyzed.The roadway combined support mode of"anchor mesh belt+anchor cable beam"is determined,and the top bolt is?22×2500 Mm type high-strength anchor rod with row spacing of 750×700 mm and top anchor cable of?21.6×8200 mm steel strand.(3)According to the structural characteristics of the machine,the supporting design of the side supporting bolt is analyzed.When the pre stress and pre tightening torque of the bolt are increased,the torque of the high-strength bolt on the roof is not less than 200 N·m,and the torque of the high-strength anchor bolt at the side is not less than 150 n·M According to the problems existing in each working procedure of excavation and support,the optimized design scheme of working procedure is put forward.By improving the construction sequence,construction method and staff handover,the driving speed of field test is increased by 31.7%.(4)The surface deformation monitoring,deep displacement monitoring and bolt(cable)stress monitoring were carried out in Chengjiao mine.The results show that the maximum roof separation is 36 mm,the maximum side displacement is 120 mm,and the floor heave is 100 mm.According to the deformation characteristics of surrounding rock of coal roadway,the cross-section form of micro trapezoid roadway with two sides of rectangular roadway inclining outward at a certain angle is designed,and the support optimization design scheme is put forward.The middle two anchor cables of four anchor cables on the roof are changed into anchor bolts,and the bolt in the center of roadway is changed into anchor cable.The two bolts at both sides of the side near the floor are inclined downward by 15°and the high stress coal roadway is effectively controlled by field application Surrounding rock deformation.This paper consists of 69 Figures,40 Tables and 87 References.