Non-isothermal behavior of excavation damaged zone

The efficient and safe disposal of high-level nuclear waste relies heavily on understanding the behavior of host rocks under thermal, hydraulic, and mechanical (THM) influences. This study focuses on the non-isothermal behavior of the excavation damaged zone (EDZ) around deep radioactive waste repositories in indurated argillaceous rocks. A novel non-isothermal model is developed, integrating a generalized effective stress framework with strength anisotropy to capture the thermomechanical response of these rocks. The model incorporates both thermo-elastic and thermo-plastic components, accounting for instantaneous and time-dependent deformation under thermal loads. Numerical simulations of in-situ heating tests at the MHM Underground Research Laboratory demonstrate the model's ability to predict the evolution of pore pressures, thermal volumetric behavior, and changes in the EDZ. Results reveal that thermal loading significantly enhances the EDZ's evolution during the heating phase, emphasizing the importance of considering thermal effects in constitutive modeling for deep geological repositories. These findings contribute to the optimization of repository design and the long-term safety of nuclear waste disposal systems.