Stability principle and control of surrounding rock in deep coal roadway with large section and thick top-coal

Based on the difficult problem of surrounding rock control in deep coal roadway with large section and thick top-coal,surrounding rock deformation and failure mechanism and its supporting technology are studied.The results show that,for deep coal roadway with large section and thick top-coal,plastic zone of top-coal presents "arched" or "inverted trapezoid" with wide upper and narrow lower,however plastic zone of immediate roof presents "rectangular";the shoulder stable region exists in the immediate roof.Bedding surface shear failure effect mechanism for "inverted trapezoid" plastic zone is proposed: under the effect of high stress(especially high horizontal stress) and horizontal stress caused by larger roof subsidence;bedding surface between top-coal and immediate roof goes to shear failure,which causes coal body near bedding surface failure;and it promotes the formation of "inverted trapezoid" plastic zone.Based on above,high prestressed bolt with strip and steel mesh combining with diagonal cable and beam structure support is put forward.It is thought that diagonal cable can be anchored to the stability region in the shoulder;and it can limit the shear deformation of bedding surface between top-coal and immediate roof,and also can prevent the development of top-coal plastic zone from "arch" to "inverted trapezoid".The research results have been successfully applied to roadway supporting.