Study On Deformation And Failure Influencing Factors And Restoration Control Of Weak Cemented Soft Rock Roadway Surrounding Rock

In recent years,with the decrease of coal resources in eastern China,the focus of coal resources mining in China has gradually shifted from east to west.Coal measures strata in Western China have a late diagenetic period and many soft rock strata.The surrounding rock of roadway arranged in this strata is of low strength,short self-stabilization time,and easy weathering,hydrolysis and muddification of rock mass,which makes roadway support difficult.Especially in weak cemented soft rock roadway,because of its complex stress and geological environment,the roadway is prone to damage and deformation.Based on the engineering research background of 2-2 coal auxiliary haulage roadway in Hongqingliang Coal Mine,Erdos,this paper analyzed the deformation and failure characteristics of surrounding rock of weak cemented soft rock roadway by combining theoretical analysis,numerical simulation,indoor experiment and on-site monitoring,and ranked the influencing factors of roadway failure significantly,and proposed bolt(cable)repair support and U-shaped steel shed.Rehabilitation and support technology and field application have achieved the following main research results:(1)Through on-site monitoring,the failure characteristics of Hongqingliang 2-2 coal auxiliary transport roadway are analyzed and summarized.The deformation rates of roof,floor and both sides of the roadway increase first and then decrease.Firstly,the grouting layer of the roadway roof cracks and destroys,the maximum subsidence of the roof is 663 mm,then the floor heave occurs,and the maximum heave is 432 mm.Finally,the side of the roadway and the maximum displacement of the two sides are 388 mm.(2)Sandy mudstone is the main lithology of roadway roof and floor,and the results of physical component test show that the content of clay minerals in roadway surrounding rock in serious deformation and failure section is as high as 30-55%,and the strength of sandy mudstone measured by laboratory test is lower,the average uniaxial compressive strength is 8.75 MPa,and the average tensile strength is 1.11 MPa.In addition,comprehensive indoor test quantitatively illustrates the weak cementation of surrounding rock.Section roadway is affected by 3-1 coal chamber group,and the structure combination of coal and rock in roadway is complex,resulting in serious deformation and destruction of roadway surrounding rock.(3)Based on the analysis of the influencing factors of deformation and failure of surrounding rock of weak cemented roadway,the influence of coal-rock structure combination,lateral pressure coefficient and arrangement of chamber group on the distribution of plastic zone of surrounding rock of roadway is studied by numerical simulation.The correlation degree between the influencing factors and the failure of surrounding rock of roadway is ranked by grey theory analysis method,and the influencing degree of each factor is determined.The results are as follows:chamber group>roadway coal-rock structure combination>lateral pressure coefficient.(4)Aiming at the severely damaged section of the roadway,the technology of bolt(cable)encrypted support and U-shaped steel shed support repair is put forward.Through numerical simulation,the optimal repair support scheme is determined,that is,two bolts(compensation structure)are installed at the leg of U-shaped steel shed,and the engineering practice is carried out.The results show that the repair support scheme can effectively maintain the stability of the roadway,and the integrity of the roadway is good.The volume deformation is not large.