Parametric Study of Influence of Corrosion Phenomena on the Thermo-Hydro-Mechanical Response of Claystone

This work is performed in the framework of feasibility study of underground repository for High-Levels radioactive Wastes. Based on the design concept of ANDRA, the retrievability of waster packages requires ensuring the mechanical stability of the steel liner for several thousand years. During the lifetime of repository, the host rock is subjected to various coupled loadings, such as mechanical loading/unloading, ventilation and temperature variation. Moreover, the steel liner may be corroded by the eventual contact of groundwater coming from the host rock and then induce a degradation of its useful properties, including strength, permeability, gas production, volumetric expansions, etc… The combinative effects of the steel corrosion and the evolution of host rock deformation may induce an eventual structural failure of steel liner and an amplified fracture damage zone in the host rock. Therefore, the long-term safety of the repository requires a detailed study on the thermo-hydro-mechanics coupling effect including corrosion phenomena on the response of host rock. In view of this, a disposal tunnel supported by a steel liner is simulated and analyzed. Using THM coupling model, a series of parametric study is then performed to identify the influence of different corrosion phenomena, for instance, the corrosion velocity, the volumetric expansion of corrosion products and the mechanical properties of corrode steel as well as the temperature. The analysis of numerical results allows us capture the important issues controlling the influence of corrosion process of steel liner on the THM response of claystone