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

在法国，计划在深部卡洛沃-牛津粘土岩 (COx) 地层中建造名为 Cigéo 的高放废物 (HLW) 和中放长寿命放射性废物 (ILW-LL)的深层地质处置设施。HLW 包释放的热量导致主岩温度升高，这主要是由于孔隙水和固体骨架之间的热膨胀差异导致孔隙压力增加。COx 的低渗透性及其相对刚性抑制了诱发压力积聚的排放。此外，热负荷还会在地层内引起热机械应力。法国国民放射性废物管理机构 (Andra) 参与了 DECOVALEX-2019 项目（任务 E），以模拟受基于法国概念的 HLW 处置库启发的基准练习的热-水-机械 (THM) 响应。本文旨在通过热-孔-弹性数值模拟，通过考虑主岩性质的固有空间变异性来研究 HLW 储存库的 THM 行为。仅选择最有影响力的参数进行空间变异性分析，方法是使用蒙特卡罗模拟结合随机有限元法。最具影响力的参数的选择基于两个参数敏感性分析，包括计算 Sobol 指数，这决定了每个输入参数对整体模型输出方差的贡献。远场中 Terzaghi 有效应力的时间演变被定义为每个参数对 THM 响应影响的指标。