On the numerical modelling of shear banding around an excavation

For an underground storage of nuclear waste, it is necessary to minimize the excavation damage zone (EDZ) that could be a higher permeability zone. This paper deals with the FE modelling of the EDZ extent during tunnelling. A Drucker – Prager law with cohesion strain softening is used. Results show a shear banding around the excavation. Its extent and the tunnel convergence are highly dependent on the hydraulic boundary condition within the tunnel (imposed pore pressure – suction or unilateral flow condition).