Electrical Resistivity Changes During Heating Experiments Unravel Heterogeneous Thermal-Hydrological-Mechanical Processes in Salt Formations

Abstract

Rock salt is considered a suitable medium for the permanent disposal of heat-generating radioactive waste due to its isolation properties. However, excavation damage and heating induce complex and heterogeneous thermal-hydrological-mechanical (THM) processes across different zones. Quantifying this heterogeneity is crucial for accurate long-term performance assessment models, but traditional methods lack the necessary resolution. This study employs 4D electrical resistivity tomography (ERT) monitoring during controlled heating experiments in a salt formation to unravel the spatiotemporal dynamics of THM processes. Advanced time-lapse inversion and clustering analysis quantify subsurface properties and map the heterogeneity of THM dynamics. The ERT results can estimate subsurface properties and delineate the damaged and intact zones, enabling appropriate parameterization and representation of processes for long-term modeling. This approach may be used in further improving the predictive models and ensuring the safe long-term disposal of radioactive waste in rock salt.