软岩巷道围岩塑性区演化规律及形态模糊判别OA

The stress disturbance caused by roadway excavation will cause the change in the plastic zone of surrounding rock,resulting in uneven deformation of surrounding rock,roof collapse,roof fall,and other engineering disasters.In order to study the influences of lateral pressure coefficient(λ)and principal stress direction on the plastic zone of surrounding rock,based on the butterfly plastic zone theory,the principal stress deflection angle(α)is introduced,and the boundary equation of plastic zone of surrounding rock considering the principal stress direction is constructed.The evolution law of plastic zone of surrounding rock under different lateral pressure coefficients and principal stress deflection angles is studied and verified by FLAC3D numerical simulation.The results show that when different λ and α act,the plastic zone of roadway surrounding rock presents three morphological characteristics:circular(CS type),oval(OS type)and butterfly(BS type).In addition,λ affects the shape of plastic zone,while α affects the failure position of surrounding rock.Together,they affect the expansion range of plastic zone.The angle between the butterfly leaf and the vertical direction changes linearly with the variation of α.Based on the theory of fuzzy mathematics,a fuzzy evaluation method of the plastic zone morphology of soft rock is proposed.Taking the 20110 working face of Gaojialiang Coal Mine as the engineering background,the reliability of the proposed evaluation method is verified by numerical simulations and field loose circle tests.An asymmetric coupling support scheme combining'long and short anchor(cable)+steel mesh+shotcrete+shallow grouting'is proposed,which significantly reduces the convergence deformation of surrounding rock surface.The research results can provide theoretical support for deformation control and disaster prevention of surrounding rock in underground engineering.