International audienceIn France, the National Radioactive Waste Management Agency (Andra) oversees the study ofa disposal for intermediate-level long-lived (IL-LLW) and high-level activity radioactive waste(HLW) in a deep claystone formation (Callovo-Oxfordian claystone, COx) in the frameworkof Cigéo project. Several in situ and laboratory THM characterization studies have beenundertaken in this formation since 2000. In parallel, theoretical analyses, constitutive modelsand numerical modelings have been developed to describe different processes during the lifeof the disposal. This paper presents a regularized anisotropic elastoplastic and damage modelincluding both non-linear short and long terms response. The influence of damage andfracturation on the transport and viscous properties are considered. The proposed model wasimplemented with a regularization scheme based on the non-local implicit gradient in ComsolMultiphysics®. After validating the model on simple stress paths, its operational nature issuccessfully evidenced on the GCS drift for which the in situ observations are the mostchallenging to reproduce. It is shown that the model is able of reproducing the measured porepressure as well as the drift convergences. Importantly, the predicted extent of damaged zonesaround the drift is consistent with the in situ observations. Secondly, the proposed model isapplied to study the THM behavior of a HLW repository. The role of the non-linear behaviorof the COx claystone on the THM responses in the near and far fields, is herein highlighted inthe framework of a benchmarking exercise within the European program EURAD HITEC
