Comparison of the hydrogeochemical and mechanical behaviours of compacted bentonite using different conceptual approaches

Abstract

This study compares the capabilities of two numerical models that simulate the behaviour of compacted saturated MX-80 bentonite exposed to different chemical environments. Both codes have different approaches: one of them is a reactive transport model, and the other is a hydrogeomechanical model. The study shows that the combined use of both approaches provides a useful basis for designing bentonite barriers in the geological disposal of high-level nuclear waste. Although, their application is now limited to simple geometries and boundary conditions, the proposed approaches are a first step towards a fully thermo-hydro-mechano-chemical model. It is also shown that there is a need for a greater understanding of the chemomechanical coupling that occurs at the microstructural scale to achieve this comprehensive model in the future.