| No.Two1 coal seam is mainly mined in Hebi No.9 coal mine.The average thickness of coal seam is 5.31 m.With the adoption of fully mechanized caving mining technology and U-shaped steel arch support in the mining roadway,there are many problems such as high labor intensity,high rate of roadway repair and the need to replace the shed in the advance support section,which restrict the high production and efficiency of the mine.According to the geological conditions of nine mine engineering,the whole coal bolt net support technology is proposed to be used in the mining roadway.In this paper,through the means of geomechanical evaluation,similar simulation,theoretical analysis,numerical simulation and field industrial test,the research on3204 down channel anchor mesh cable support in Hebi jiukuang mine is carried out,and the following conclusions are obtained:(1)For the No.Two1 coal body of Hebi No.9 mine,its uniaxial compressive strength is 1.06 MPa,the coal body firmness coefficient is 0.14,the average buried depth of the roadway is 700 m,and the vertical stress is 17.5MPa.The surrounding rock load of the roadway is large,the coal body and easily become loose due to deformation,resulting in the loss of empty roof phenomenon,resulting in uneven loading of U-shaped steel shed,reducing its bearing capacity and stability.When the surrounding rock of the roadway is rapidly deformed,the U-shaped steel shed loses stability rapidly,and the roadway section shrinks back,which affects the safe and efficient production of the mine.(2)Using similar simulation methods,the deformation and failure characteristics of surrounding rock under the influence of mining under unsupported,thin-top coal anchor mesh cable support and thick top coal reinforced anchor mesh cable support roadway are studied.Control mechanism of broken coal roadway.By increasing the support density of the anchor cable and the prestress of the anchor cable,the stress state of the surrounding rock of the soft and broken roof roadway is improved,and the surrounding pressure of the roadway can be increased to improve the bearing capacity of the surrounding rock and the strength of the surrounding rock.Strengthen and control the development of the surrounding rock crushing zone and plastic zone,so as to keep the surrounding rock of the roadway stable;improving the surface protection ability of the supporting member can effectively control the loss of soft fracture,thereby reducing the failure of the anchor bolt.(3)Through theoretical calculation and similar simulation results of engineering analogy method,it is determined that the supporting principle of down channel anchor wire mesh cable in 3204 is coordinated support of high prestress,high strength and high density anchor cable,and the specific supporting scheme is that the top and side anchor rod are ? 22 × 2400 mm high-strength left-handed non longitudinal reinforced screw steel anchor rod(top 8-side 5),with row spacing of 700 × 700mm;the top anchor cable is ? 22 × 830 mm anchor cable,side anchor cable Select ? 22 ×5300mm anchor cable(top 3-sides 1),row spacing 1400 mm.Through the numerical simulation,the supporting effect of the roadway during the excavation and mining is verified,which further explains the rationality of the supporting scheme.(4)According to the research results,the industrial test is carried out in the 3204 lower chute,and the monitoring data of mine pressure verify the rationality of the support scheme.The surrounding rock of the 3204 lower chute is in a relatively stable state under the anchor mesh cable support scheme.The industrial test shows that the supporting effect of roadway is good,and it has significant economic and social benefits. |
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