The Callovo-Oxfordian (COx) claystone is considered as a candidate host rock for a deep geological radioactive waste repository in France. Due to the exothermic waste packages, the rock is expected to be submitted to temperatures up to 90 °C. The temperature rise induces deformations of the host rock, together with an increase in pore pressures, involving complex thermo-hydro-mechanical (THM) couplings. This study aims to better characterize the THM response of the COx claystone to temperature changes in the laboratory. To this end, claystone specimens were tested in a temperature controlled, high pressure isotropic compression cell, under stress conditions close to the in-situ ones. Thermal loads were applied on the specimens along different heating and cooling paths. A temperature corrected strain gage system provided precise measurements of the anisotropic strain response of the specimens. Drained and undrained thermal expansion coefficients in both transversely isotropic directions were determined. The measurement of pore pressure changes in undrained condition yielded the thermal pressurization coefficient. All parameters were analysed for their compatibility within the thermo-poro-elastic framework, and their stress and temperature dependency was identified.

中文翻译：

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横向各向同性页岩的热孔弹性行为：热膨胀和加压

Callovo-Oxfordian (COx) 粘土岩被认为是法国深层地质放射性废物处置库的候选主岩。由于废物包放热，预计岩石将承受高达 90 °C 的温度。温度升高导致主岩变形，同时孔隙压力增加，涉及复杂的热-水-机械 (THM) 耦合。本研究旨在更好地表征 COx 粘土岩对实验室温度变化的 THM 响应。为此，在接近原位应力条件的温度控制、高压各向同性压缩室中对粘土岩试样进行了测试。沿不同的加热和冷却路径对试样施加热载荷。温度校正应变计系统提供了试样各向异性应变响应的精确测量值。确定了两个横向各向同性方向上的排水和不排水热膨胀系数。不排水条件下孔隙压力变化的测量产生了热加压系数。分析了所有参数在热孔弹性框架内的兼容性，并确定了它们的应力和温度依赖性。