Compacted bentonite is often considered as a possible buffer/backfill material for deep geological disposal of high-level radioactive waste. During the long-term lifespan, the bentonite barriers will undergo coupled thermo-hydro-mechanical (THM) progresses, which induce complex volume changes. In this work, the volume change behavior of compacted bentonites undergoing THM interactions was analyzed based on the framework of Barcelona Expansive Model, in which the thermal volume changes were taken into account by adopting the approach of Tang and Cui (Géotechnique 59:185–195, 2009). After analyzing the published experimental results of wetting/drying and heating/cooling cycles, new f_I and f_D functions were put forward for describing the interaction between micro- and macro-structures, while a thermal loading yield function curve was established for describing the TM behavior under unsaturated conditions. Some cyclic wetting/drying and thermal loading tests reported and modelled in literature were simulated to verify the relevance of the improvements undertaken. Comparisons among the original model, the modified model as well as the test results clearly showed a satisfactory performance of the model in describing the volume changes of compacted swelling clays upon THM processes.

压实膨润土通常被认为是一种可能的缓冲/回填材料，用于高放射性废物的深层地质处置。在长期使用寿命期间，膨润土屏障将经历耦合的热-水-机械 (THM) 进程，这会导致复杂的体积变化。在这项工作中，基于巴塞罗那膨胀模型的框架分析了经过 THM 相互作用的压实膨润土的体积变化行为，其中采用 Tang 和 Cui (Géotechnique 59:185–195) 的方法考虑了热体积变化, 2009)。在分析润湿/干燥和加热/冷却循环的已发表实验结果后，新的f _I和f _D提出了描述微观和宏观结构之间相互作用的函数，而建立了热载荷屈服函数曲线来描述不饱和条件下的TM行为。对文献中报告和建模的一些循环润湿/干燥和热负荷测试进行了模拟，以验证所进行改进的相关性。原始模型、修改模型以及试验结果的比较清楚地表明，该模型在描述 THM 过程中压实膨胀粘土的体积变化方面具有令人满意的性能。