Simulations of the thermo-hydro-mechanical behaviour of an annular reinforced concrete structure heated up to 200 °C

We analyze in this study the numerical thermo-hydro-mechanical response of an annular reinforced concrete structure called MAQBETH subjected to a thermal loading up to 200 °C during more than 250 h. This mock-up is typical of concrete structures in nuclear waste storage conditions under accidental situations. The simulations are performed with a simplified coupled model based on the mechanics of partially saturated porous media, which was previously developed in [1]. As a main contribution of this paper, we explicitly take into account the temperature effects in the water retention curves, via the introduction of the isosteric heat of sorption. These effects result in a significant reduction of the saturation degree at any given relative humidity for increasing temperatures. The numerical results of the MAQBETH simulation are then compared with experimental ones in terms of profiles of temperature, relative humidity, gas pressures and strains in the median plan at different times. This comparison shows a reasonable agreement. The effects of the temperature-dependent sorption curves are further analyzed through additional simulations carried out with a constant sorption curve. Large differences in the relative humidity and saturation degree profiles, and to a lesser extent in the gas pressure profiles, are observed between the two cases.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The THM behaviour of the MAQBETH structure is correctly simulated. ► Macroscopic damage is due essentially to temperature gradients. ► The temperature-dependent sorption curves affect the saturation profiles. ► The drying process occurs faster and with a very marked front.