Numerical simulation of zonal disintegration of surrounding rock in the deep-buried chamber

Zonal disintegration is the phenomenon of cyclical rupture zone and nonrupture zone in the surrounding rock of a deep-buried chamber,which is different from that of a shallow chamber.Based on the finite difference software FLAC3D,the numerical simulation of surrounding rock with different mechanical parameters was conducted by using the SU model(Bilinear Strain-Softening Ubiquitous-Joint).The influences of buried depth,cohesion,and internal friction angle of surrounding rock on zonal disintegration were analyzed to reveal the influence law.The results show that:(1) after the chamber excavation,multiple rupture zones gradually extend from the chamber surface or adjacent periphery to the deep surrounding rock.In the extension process,a single rupture zone may be forked into two or even multiple rupture zones,which cross each other and form the zonal disintegration zone.(2) Zonal disintegration is affected by both σ(in situ stress) and Ucs(uniaxial compression strength).Smaller Ucsand larger σwill lead to zonal disintegration.(3) The zoning fracture is not obvious in the case of σ≤ Ucs.In the reverse case,zoning fracture appears remarkably in the surrounding rock around the chamber.These results reveal the influence law of zonal disintegration and provide theoretical support for the design of deep-buried chambers.