Effects of inherent spatial variability of rock properties on the thermo-hydro-mechanical responses of a high-level radioactive waste repository

In France, a deep geological disposal for high level radioactive waste (HLW) and intermediate-level long-lived (ILW-LL) called Cigéo is planned to be constructed in Callovo-Oxfordian claystone (COx) formation. The heat released from the HLW packages leads temperature increase host rock, which causes pore pressure essentially due difference between thermal expansion of water solid skeleton. low permeability COx its relative rigidity inhibit discharge induced build-up. Moreover, loading also induces thermo-mechanical stresses within French National Radioactive Waste Management Agency (Andra) participated DECOVALEX-2019 project (Task E) model Thermo-Hydro-Mechanical (THM) responses benchmark exercise inspired repository based on concept. This paper aims at studying THM behavior by taking into account inherent spatial variability properties rock through thermo-poro-elastic numerical simulations. Only most influential parameters were selected perform analysis using Monte Carlo simulations coupled with Random Finite Element Method. selection was two parametric sensitivity analyses consisting computing Sobol indices, determine contribution each input parameter overall output variance. temporal evolution Terzaghi effective stress far field defined as indicator influence response.