Discussions on Zonal Disintegration around Tunnel in Deep Rock Mass

Questions related to zonal disintegration such as difference between results from laboratory test and field monitoring test, as well as the effect of multi-axial stress level on zonal disintegration were discussed through numerical modeling by using a 3D numerical code called RFPA3D. Results show that the much smaller fracture spacing captured by laboratory test on zonal disintegration is due to the heterogeneity extent of the tested material. Zonal disintegration is an inherent character of heterogeneous rock mass, the more the heterogeneous the rock is, the larger the spacing between the adjacent fractures will be. The configuration of zonal disintegration is influenced by combination of stress level in three directions. Intact fracture rings can not be formed unless a nearly hydrostatic stress state exists in directions perpendicular to tunnel axis.