Study On Support Technology Of Roadway In Three Soft Coal Seams Of Luohuaya Coal Mine

The roadway excavated and maintained in the three soft coal seam has the advantages of long continuous deformation time,fast deformation speed and large deformation.For a long time,the supporting problem of the roadway in the three soft coal seam has been a difficult problem perplexing the production.Based on the roadway support problem of the auxiliary inclined shaft passing through the three soft strata in Luohuaya Coal Mine,this paper makes a comprehensive and systematic study on the roadway support technology of the three soft coal seam by means of indoor test,field monitoring,theoretical analysis,numerical simulation and so on.(1)Through the laboratory tests of uniaxial compression,triaxial compression and Brazilian fracturing,the strength and deformation indexes of surrounding rock were obtained.The analysis shown that the mudstone in roadway roof and floor has weak resistance to deformation and failure and low peak strength,which belongs to typical soft rock.(2)Through the on-the-spot monitoring of the roadway in the typical area of three soft areas,the deformation law of large deformation and long deformation duration of roadway in Luohuaya Coal Mine was mastered,the semicircle of roadway straight wall was equivalent to circular by using equivalent radius method,the stress elastic-plastic solution of roadway surrounding rock stress was deduced,and the stress distribution of semi-circular arch roadway with auxiliary inclined shaft in Luohuaya Coal Mine was calculated.The comprehensive analysis reveals the deformation mechanism of the three soft roadway:? With the continuous increase of the surrounding rock deformation,the stress state of the surrounding rock of the roadway was deteriorating,the stress of the wall on both sides of the roadway was transferred to the floor,and the surrounding rock at the floor enters the plastic flow state,and the floor heave continues.?With the increase of stress level,mudstone shown significant rheological property,and the deformation of mudstone enters the stage of accelerated creep,and the final deformation can reach more than 3 times of elastic-plastic deformation.(3)Through the calculation of support theory,two kinds of support optimization schemes,anchor mesh cable+spray layer+W-shaped steel strip support and anchor mesh shotcreting+U29 arch frame combined support were put forward,and the numerical simulation comparative test between the original support scheme and the support optimization scheme was carried out by using FLAC3D The results show that compared with the original support scheme,the bottom heave of surrounding rock with anchor mesh shotcreting+U29 arch support scheme was reduced by 56.7%,the stress and plastic failure of surrounding rock were obviously improved,and the volume of plastic zone was reduced by 52%.The supporting members did not enter the limit state prematurely.The indexes shown that the combined support of anchor,mesh and shotcreting+U29 arch frame has the best effect on controlling the stress of surrounding rock.(4)The optimized support scheme was applied in engineering,and the deformation of roadway was monitored by high precision total station.The monitoring results shown that the maximum convergence deformation of both sides of roadway was 90mm,the maximum subsidence of roof was 36mm,and the amount of bottom heave was 32mm.The deformation of roadway has been effectively controlled,and the effect of support optimization is remarkable.