Numerical modeling of the influence of steel corrosion on the thermo-hydro-mechanical response of the Callovo-Oxfordian claystone

In this paper, the effects of steel corrosion on the THM response of the geological barrier is studied by simulating a disposal tunnel of high-level radioactive wastes (HLW). The simulation is performed by using a coupled THM finite element code and two different constitutive models: a visco-elastoplastic model for the geological barrier and a von-Mises type model for the steel barriers. The corrosion effects are numerically simulated by a decrease of mechanical properties of steel and a volumetric expansion related to corrosion products. The detailed geometries of engineered barriers and their internal void spaces are incorporated into the numerical simulation. The evolutions of temperature, liquid pressure, displacement, and stress fields in the geological barrier (called the Callovo-Oxfordian claystone) are analyzed. The numerical results exhibit that the influence of steel corrosion on the THM response of the claystone is limited in the near field of disposal tunnel, especially for the displacement and stress fields in the claystone. However, the evolutions of temperature, liquid pressure and plastic zone in the claystone are not disturbed by the corrosion process of steel barriers and are controlled essentially by its THM properties.