Thermo-Hydro-Mechanical Modelling of Hollow Cylinder Laboratory Experiments on Boom Clay

The aim of the TIMODAZ project is to investigate the effect of thermal changes on the excavation damaged zone (EDZ) around nuclear deep disposals in clay-based geological formations. In the framework of WP5.2 of this project, it is intended to develop constitutive models and numerical tools reproducing the thermo-hydro-mechanical (THM) evolution of the host rocks at real time and repository scale. Predictive THM modelling of on-going laboratory experiments has been realised by several partners of the project to compare different finite element codes and to provide a first insight into the THM responses of the tested materials. The experiment consists of a hollow cylinder of clayey material, which is subjected to THM loadings. The modelling of this experiment is realised with different constitutive laws (thermo-elasticity, elastic-perfectly plastic laws, hardening plasticity and/or thermo-plasticity). Results show that the choice of the THM model is a key issue for the prediction of the process implied in this modelling. For the current objective of this work, the assumption of isotropy was found to be fair enough. However, preliminary experimental results got in WP3 of the present project point out a certain mechanical anisotropy of the tested clay. Consequently, further development of constitutive laws considering mechanical anisotropy will probably be necessary in the future.