Saeed Tourchi , Miguel Angel Manica Malcom, Jean Vaunat, Antonio Gens

The paper presents the enhancement of an existing constitutive model for argillaceous
hard soils-weak rocks for non-isothermal conditions, to be used in coupled
thermo-hydro-mechanical (THM) simulations of underground excavations subjected to
temperature variations within the context of deep geological nuclear waste disposal. The
proposed thermo-elastoplastic extension accounts for the effect of temperature on the
yield and plastic potential functions, and on the elastic stiffness. The resulting model
is validated through the simulation of relevant non-isothermal laboratory tests reported
in the literature. The model is then applied to the coupled THM simulation of an in
situ heating test conducted at the Meuse/Haute-Marne underground research laboratory,
in Bure, France, excavated in the Callovo-Oxfordian claystone. Results show that the
incorporation of thermal effects into the constitutive description of the host rock plays
a significant role in the behaviour of the excavation when subjected to thermal loading,
particularly in the evolution of the excavation damaged zone.