A softening damage-based model for the failure zone around deep tunnels in quasi-brittle claystone

The excavation of galleries in deep rocks induces the formation of failure zones around these structures. For semi-brittle rocks, accounting for softening damage phenomena seems necessary for a correct description of the short term failure around galleries perimeter. In this work, an elastic-damage softening model with anisotropic shear strength is employed to analyze the short term extension of the excavation-induced failure zone as well as the displacements of the tunnels walls. No presence of support syste is considered in the performed numerical analyses.