Effect of mechanical non-linearities on the thermal-hydraulic-mechanical response of a geological repository
Résumé
In France, the National Radioactive Waste Management Agency (Andra) oversees the study of
a 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 framework
of Cigéo project. Several in situ and laboratory THM characterization studies have been
undertaken in this formation since 2000. In parallel, theoretical analyses, constitutive models
and numerical modelings have been developed to describe different processes during the life
of the disposal. This paper presents a regularized anisotropic elastoplastic and damage model
including both non-linear short and long terms response. The influence of damage and
fracturation on the transport and viscous properties are considered. The proposed model was
implemented with a regularization scheme based on the non-local implicit gradient in Comsol
Multiphysics®. After validating the model on simple stress paths, its operational nature is
successfully evidenced on the GCS drift for which the in situ observations are the most
challenging to reproduce. It is shown that the model is able of reproducing the measured pore
pressure as well as the drift convergences. Importantly, the predicted extent of damaged zones
around the drift is consistent with the in situ observations. Secondly, the proposed model is
applied to study the THM behavior of a HLW repository. The role of the non-linear behavior
of the COx claystone on the THM responses in the near and far fields, is herein highlighted in
the framework of a benchmarking exercise within the European program EURAD HITEC.
Domaines
Sciences de la Terre
Origine : Fichiers produits par l'(les) auteur(s)