The coupled Thermo-Hydro-Mechanical (THM) behavior of the Callovo-Oxfordian claystone (COx) is of great importance for the design and safety calculations of the high-level radioactive waste disposal project in this potential host rock in France. The heat emitted by the waste causes a pore pressure increase within the surrounding rock essentially due to the differential thermal expansion of the pore water and the solid skeleton. The low permeability of the COx and its relative rigidity inhibits the discharge of the induced pressure build-up. Moreover, thermal loading may provoke thermo-mechanical stresses within the formation due to mechanical confinement by the rigidity of the surrounding host rock. An important research program has been conducted by the French National Radioactive Waste Management Agency (Andra) since 2003 in order to investigate the THM response of the COx under thermal loading, through laboratory tests, in-situ experiments, model development and numerical modeling. Within Task E of the DECOVALEX-2019 project, five research teams investigated upscaling THM modeling from a small-scale in-situ experiment (TED) to a full-scale in-situ experiment (ALC). The upscaling modeling started with a verification test to validate the numerical codes. Then, an interpretative modeling of the TED experiment was performed to calibrate the THM parameters of the COx. Finally, the calibrated THM parameters were used for a blind prediction of the ALC experiment. The modeling teams each adopted a thermo-poro-elastic approach which yielded satisfactory results. The blind prediction of the temperature field showed an overestimation of less than 2 °C which was considered acceptable. On the other hand, pore pressure was well predicted only in the direction parallel to the bedding whereas the slow dissipation of the pore pressure in the direction perpendicular to the bedding was not captured by any of the modeling teams – which remains an open question of the present study.

Callovo-Oxfordian 粘土岩 (COx) 的耦合热-水力-机械 (THM) 行为对于法国这块潜在母岩中的高放废物处置项目的设计和安全计算非常重要。废物散发的热量导致围岩内的孔隙压力增加，这主要是由于孔隙水和固体骨架的不同热膨胀。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，由于周围主岩刚性的机械限制，热载荷可能会在地层内引起热机械应力。自 2003 年以来，法国国家放射性废物管理局 (Andra) 开展了一项重要的研究计划，旨在通过实验室测试、原位实验、模型开发和数值建模来研究热负荷下 COx 的 THM 响应。在 DECOVALEX-2019 项目的任务 E 中，五个研究团队研究了将 THM 建模从小规模原位实验 (TED) 升级到全尺寸原位实验 (ALC)。升级建模从验证测试开始，以验证数字代码。然后，对 TED 实验进行解释性建模以校准 COx 的 THM 参数。最后，校准的 THM 参数用于 ALC 实验的盲预测。建模团队各自采用了热孔弹性方法，结果令人满意。温度场的盲目预测显示高估小于 2°C，这被认为是可以接受的。另一方面，孔隙压力仅在平行于层理的方向上得到了很好的预测，而在垂直于层理的方向上孔隙压力的缓慢消散没有被任何建模团队捕获——这仍然是一个悬而未决的问题目前的学习。