Research On Combined Support Technology Of Anchor Net And Cable In Mining Roadway Of Deep Mine Composite Roof In Pingdingshan No.4 Mine

With the increase of coal mining intensity,the shallow resources are gradually depleted,the coal mining is gradually shifting to the deep,the mining conditions are more and more complicated,and the requirements for roadway support are also constantly improved,especially under the condition of composite roof,the joint of anchor nets is studied.Support is of great significance for improving the efficient production of deep wells.Taking the wind tunnel of 15-31020 working face of Pingmei No.4 Mine as an example,this paper systematically studies the combined support of anchor roof and cable in composite roof roadway through field investigation,laboratory experiment,theoretical analysis and numerical simulation.Through the engineering test,the reasonable reliability of the support scheme is verified,which can provide reference for the roadway support under similar conditions.The main results are as follows:(1)The geological profile of the roadway was analyzed.At the same time,the physical and mechanical parameters of the coal and roof rock samples were measured by SANS in the laboratory.The results show that the top and bottom mudstones and silty mudstones have low strength and resistance.The compressive strength is between 25 and 35 MPa,and the joint fissures of the rock formation are relatively developed.(2)Combining the mechanical model of composite roof,the characteristics of its force and damage were studied.The results show that due to the different elastic modulus and layer thickness of each rock layer of the composite roof,the deflection and strength of each rock layer in the roof are different,which causes damage in the soft rock.Combined with the actual situation of the roadway,the main factors affecting the deformation and failure of the surrounding rock in the deep mine roadway are the high ground stress conditions and the low strength of the surrounding rock of the roadway.The mechanical properties are poor,and the existence of the weak interlayer and the stress concentration of the shoulder are easy to cause the anchorage of the key part.(3)Combined with the action and support mechanism of the anchor cable and cable joint support components(anchor,anchor cable,metal mesh,steel strip),a shear anchor net with improved preload and short anchor cable instead of shoulder anchor is proposed.The cable joint active support technology improves the original support plan.Through the suspension theory and the combined arch theory to calculate the relevant parameters,the support scheme was designed,and the support effect was simulated by FLAC3 D simulation software.The results show that the displacement of the top and bottom of the roadway and the displacement of the two gangs are within the allowable range.(4)Carry out industrial tests on the support scheme,and put forward the construction technology and requirements for roadway support.The results of monitoring the surface displacement of the wind tunnel and the separation of the roof from the 15-31020 working face indicate that the deformation of the surrounding rock and the separation layer are small,and the overall section reduction of the roadway is 5.3%,and the support effect is good.