Modelling the density homogenisation of a block and granular bentonite buffer upon non‐isothermal saturation

This paper presents a numerical analysis of the mechanical performance bentonite clay buffer for containment nuclear waste in context deep geological disposal. The design is based on Swiss concept where canisters are emplaced pedestals compacted blocks and remaining space between tunnel canister backfilled with grains highly bentonite. A complete long-term repository requires good understanding evolution upon heating from radioactive hydration host rock. Despite its importance, implications initial heterogeneous layout, characterised by grains, final dry density at scale steady state have not been previously studied. present study aims to shed light into these processes means finite element modelling using an advanced constitutive model behaviour that considers several thermo-hydro-mechanical couplings. shown be able reproduce laboratory tests involving saturation block pellets different densities. predictions, extended up 100,000 years, indicate tend homogenise terms as reaches full saturation. Due swelling potential pedestal granular backfill, subjected movements, although remain relatively small. impact segregation also studied it seen affect substantially buffer, might reduce displacements.