Effect of pore fluid chemistry on the hydro-mechanical behaviour of poorly indurated Boom Clay

In the context of deep geological disposal of radioactive waste, particular attention is required for intermediate-level bituminized waste such as Eurobitum, which contains high concentrations of soluble salts, mainly sodium nitrate (NaNO₃). Groundwater infiltration over time is expected to cause Eurobitum swelling and the release of a concentrated saline plume, potentially inducing chemo-hydro-mechanical (CHM) disturbances in the surrounding Boom Clay (BC) formation. This study uses 2D finite element simulations LAGAMINE with the ACC2-Chem model to evaluate the CHM response of Boom Clay at the repository scale across four phases: excavation, drainage, equilibrium, and swelling with saline diffusion. Swelling is modeled by imposed radial displacements on the liner, and chemical effects by diffusion of a saline plume. Despite conservative assumptions, the results - pore pressure, displacement, stress changes, and stress paths - help improve understanding of CHM couplings and the long-term performance of Boom Clay.