In situ microscale characterisation of the thermally induced strain in a clay rock

The project aims to characterise the thermal deformation modes in a clayey rock at the microstructure scale. The rock is multiphase with a heterogeneous solid phase and a complex fluid phase (free water, absorbed water). Solid phase is composed of mineral inclusions (size of a few tens of microns) embedded in a porous clay matrix. Due to the contrast in thermal expansion of the different phases and heterogeneities, heating will induce thermal overpressurisation of the fluid in undrained conditions. The damage modes at the microstructure scale (inclusions) are poorly understood. The aim of the study will be to quantify the deformation mechanisms using microtomography imaging (sub-micron resolution) combined with image correlation. Studied specimens come the Cigeo nuclear waste disposal site.