Modelling the Excavated damage zone around an underground gallery- Coupling mechanical, thermal and hydraulical aspects

A zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed in clay around underground excavations. The stress perturbation around the excavation could lead to a significant increase of the permeability, related to diffuse and/or localized crack propagation in the material. Further the drainage and the heating of disposal will modified the size and the structure of the damage zone. The main objective of the study is to model these processes at small and large scale in order to assess their impacts on the performance of radioactive waste geological repositories. This paper concerns more particularly the thermo-hydro-mechanical modelling of a hollow cylinder experiment performed in Boom Clay and the hydro-mechanical modelling of a long term dilatometer experiment performed in Opalinus Clay at Mont Terri Rock Laboratory in Switzerland. This study shows that simple models already permit to reproduce the behaviours observed experimentally.