A double-scale modelling approach for hydro-mechanical coupling

An approach is investigated for the modelling of the hydro-mechanical coupled
behaviour of Callovo-Oxfordian claystone, a potential host rock for radioactive waste repositories
in France. This approach is a double-scale finite element method, distinguishing a micro and
a macro scale. At the micro level a representative elementary volume (REV) is used to model the
material behaviour. The global response of this REV serves as an implicit constitutive law for
the macro scale. On the macro scale, a poro-mechanical continuum is defined with fully coupled
hydro-mechanical behaviour, the micro scale contains a model that takes into account the material
micro structure to provide the material response to deformation and the associated stiffness
matrices. Computational homogenization is used to retrieve the macro tangent stiffness from the
micro level. This double scale approach is applied in the simulation of biaxial deformation tests,
demonstrating the possibility of using the double scale modelling approach with the presented
model at the micro level. The response at the macro level is compared with the micro-mechanical
behaviour.