ABSTRACT
In the context of deep geological radioactive waste disposal, significant amount of generated gas is expected to migrate from the repositories into the surrounding host rock, affecting its hydro-mechanical state. In Switzerland, Opalinus Clay is the selected host geological formation and requires a comprehensive understanding of the relevant phenomena that characterize its behaviour associated with gas transport regarding the long-term safety assessment of the repository. In this context, water and gas injection tests were performed using a high pressure oedometer cell. The results suggest that gas-induced porewater displacement is a key feature during gas invasion processes in clay-rich host rock. Furthermore, water permeability was not impacted by gas transport and consistently found in the order of 10-21 (m2) before and after the gas invasion tests. The experimental outcome of the study provided unique observations of the hydro-mechanical behaviour of Opalinus Clay when subjected to gas transport in the short-term and long-term.
