Compacted expansive clays are often considered as a possible buffer material
in high-level deep radioactive waste disposals. After the installation of waste
canisters, the engineered clay barriers are subjected to
thermo-hydro-mechanical actions in the form of water infiltration from the
geological barrier, heat dissipation from the radioactive waste canisters, and
stresses generated by clay swelling under almost confined conditions. The aim
of the present work is to develop a constitutive model that is able to describe
the behaviour of compacted expansive clays under these coupled
thermo-hydro-mechanical actions. The proposed model is based on two existing
models: one for the hydro-mechanical behaviour of compacted expansive clays and
another for the thermo-mechanical behaviour of saturated clays. The elaborated
model has been validated using the thermo-hydro-mechanical test results on the
compacted MX80 bentonite. Comparison between the model prediction and the
experimental data show that this model is able to reproduce the main features
of volume changes: heating at constant suction and pressure induces either
expansion or contraction; the mean yield stress changes with variations of
suction or temperature
