THM process development in claystone under final repository conditions

In addition to salt and crystalline rocks, clay is considered as a potentially suitable host rock for the disposal of heat-generating radioactive waste in Germany. In addition, claystone is used as a material for creating geotechnical barriers. In general, claystone should ensure the insulation of contaminated fluids through its favorable sealing material properties in the repository. These favorable material properties can be influenced by processes in the operational (for example, driving up the pit cavities) and after-operation phase or after closure of the repository (for example thermal input by the waste packages). The present work first gives an overview of the process behavior of claystone from rock mechanic and repository relevant view. Here, the theoretical basis is shown, which processes in the claystone in the operating and post-operational phase run from an integrity-relevant point of view. Based on this understanding, it is investigated which material models are suitable for simulating the complex hydraulic-mechanical material behavior of claystone. The creation of such material models and their appropriate parameterization, represents a major challenge to prove the long-term safety of a repository for heat-generating radioactive waste in claystone.