THM modelling for the HotBENT experiment using a 3D model

The HotBENT experiment being conducted at the Grimsel Test Site investigates the effects of temperatures up to 200 °C at the surface of waste disposal containers on buffer materials and the host rock of a deep geological repository. The objective of this experiment is to reduce the repository footprint by increasing the thermal loading of the containers while taking into account that vapour convection, delayed saturation and time-dependent density distribution can occur in a high-temperature environment due to the strong thermal gradients. So far, a TH-coupled analysis has been performed for the HotBENT experiment, but the results have not been benchmarked by means of a THM-coupled analysis using a 3D model. Therefore, in this study, a 3D THM-coupled analysis was performed to investigate the reproducibility of the mechanical effects in a high-temperature environment. Results show that this study was able to partially reproduce the trends of the temperature sensors installed in the experiment. To improve the reproducibility of the analysis results, it was found that it is not only necessary to modify the constitutive law of thermal conductivity or the parameters, but also to reconsider the parameters of the two-phase flow.