The impact of tunnel shape, orientation and blast round length on excavation damage zone development in brittle rock
The understanding of excavation damage zone (EDZ) for shafts, tunnel networks and storage voids within high level nuclear waste deep geological repositories (DGRs) is paramount in ensuring long term stability and safety. The EDZ consists of zones of influenced, damaged and fractured rock moving radially from the excavation. The outer “influenced” zone consists of rock that has been elastically strained, while the “damaged” zone undergoes small scale crack damage, subsequently increasing the permeability of the surrounding rock. The “fractured” zone is located nearest to the excavation wall, whereby continuous fractures form, posing a serious issue as they further promote fluid mobility. The effects of macro-geometry choices and details can be critical to EDZ and highly damaged zone (HDZ) development. 3D modelling tools and brittle constitutive models were used to explore the impacts of geometric choices and details to optimize conceptual designs.