their confinement in a nuclear power plant, the mechanical properties of the constitutive
materials of concrete change as a result of ageing. This is due to the
transportation of chemical species at the microscopic level of the media.
Firstly, this can be modelled with average equations. The Fick laws represent
the evolution of chemical diffusion and the Fourier laws, the transportation of
heat at a mesoscopic level. In this research, we will consider thermal evolution
on a fractured media.
thermomechanical problem is solved with a staggered method. The mechanical contribution
used an approach based on multi-bodies system linked with cohesive zone models.
The thermal problem is based on the approximation of the heat transfer equation
at the cohesive interface. This approach has been implemented and validated.
The description of the heat trough the interface is composed with the
definition of an homogenized conductivity and the local damage parameter.
In order to
optimize the computational cost with a good agreement of the crack propagation,
a criterion is proposed for sizing a representative elementary volume (REV). The
eigenerosion method is used, validated and extended to heterogeneous media. Two
studies are carried out on the morphological properties on a cementious media.
As a result of those studies, a minimal size for a REV is defined.
spread under thermal loads are investigated on a media representing the
concrete of the containment of a nuclear power station. The ageing effects are
taken into account as an initial damage between the mortar and the aggregates.
These parameters are expressed in terms of rate of initial damage. A study is
proposed for different values of this rate. As assumed, the development of
multi-cracks is linked with the rate of initial damage and the creation of
thermal border is proposed.