Research On The Instability Law And Control Technology Of Surrounding Rock In ShanYang Coal Mine Composite Roof Back Mining Roadway

With the continuous increase of coal seam mining depth,especially in the case of soft coal seam,soft roof,fissure water and other factors,the support of composite roof roadways is becoming more and more difficult.The main characteristics of the thick composite roof of Shan Yang Mine in ChengHe Mining Area are soft lithology of coal rock,small thickness of direct top layering,large number of layers,and difficult maintenance of roadways.Therefore,in view of the problem of thick composite roof roadway support in ChengHe Mining Area,this paper takes the 5#coal seam 1501 track alley of Shan Yang Coal Mine as the engineering background,studies the failure mechanism and support problem of thick composite roof soft rock roadway,summarizes the roof failure law of composite roof soft rock roadway,and proposes a reasonable support scheme.Through the physical and mechanical parameter experiments,the physical parameters of each rock layer of the roof plate were analyzed,and the upper sandy mud-stone was determined to be an expansion rock,the expansion rate of soft rock was 42.3%,and the maximum expansion stress was 198.2kPa.At the same time,the drilling peeping instrument was used to observe the 1501 working surface return wind alley,and it was obtained that the loosening range of the surrounding rock of the alley was 1.5 to 2.8m,the top plate was 4 to 6.5 m,the maximum convergence of the two gangs of the deformation of the composite roof roadway reached 351mm,and the maximum sinking amount of the top plate reached 831mm,and according to the distribution of the roof cover,the roof was a composite roof structure of"sandy mud-stone+fine sandstone +sandstone mud-stone".Through theoretical analysis,the mechanical model of the composite roof of the roadway of ShanYang Coal Mine was established,the tensile stress of each rock layer of the composite roof plate was derived,and the stability of each rock layer under the action of expansion stress was judged,and the instability mechanism of the surrounding rock of the composite roof of the composite roof back mining roadway of ShanYang Coal Mine was obtained,which was the expansion stress and self-weight load of the weak composite roof plate under the K4 stable rock layer that were prone to flexion deformation damage due to the expansion stress and self-weight load of the water absorption expansion.Physical similar simulation experiments can be shown that the composite roof of ShanYang Coal Mine is subjected to expansion stress under the original support conditions,and the deformation and damage of the surrounding rock of the roadway is serious,and the maximum sinking amount of the roof plate is 836mm,and the maximum convergence of the two gangs is 356mm.On the basis of theoretical analysis and experimental research,the numerical simulation analysis of different support schemes was carried out,a reasonable support scheme was proposed,and the surrounding rock transport situation and anchor rod(cable)force and the displacement of the roof plate and the two gangs of the roadway were analyzed through on-site measurement,which verified that the new support scheme could effectively inhibit the delamination of the composite roof plate of the soft rock roadway,reduce the failure depth of the roof plate,and achieve a good support effect,which met the control requirements of the stability of the composite roof of the ShanYang Coal Mine.