The final disposal of high-level radioactive waste in geological repositories envisages an engineered barrier system with a bentonite buffer, which will be subjected to strongly coupled thermal, hydrodynamic, geochemical and mechanical (THCM) processes. This paper presents coupled THCM numerical simulations of laboratory and in situ tests performed with compacted Full-scale Engineered Barrier Experiment (Febex) bentonite having different space and time scales. The simulations of the heating and hydration tests fit the measured temperature, water content and water intake data and reproduce the trends of the geochemical data. Although simulation results of the tests display similar trends, they show differences due to geometry and initial and confining conditions. The changes in porosity due to mineral dissolution/precipitation are not relevant in these tests but become relevant in long-term simulations, which show that the precipitation of corrosion products reduces significantly the porosity of the bentonite near the canister and causes pore clogging. The thickness of the bentonite alteration band is simulated to be smaller than 7 cm after 1 Ma.

中文翻译：

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放射性废物处理工程屏障系统的THCM数值模拟

地质处置库中高放废物的最终处置设想了一个带有膨润土缓冲液的工程屏障系统，该系统将经受热，水动力，地球化学和机械（THCM）过程的强耦合。本文介绍了使用空间和时间尺度不同的紧凑型全尺寸工程屏障实验（Febex）膨润土进行的实验室和现场测试的THCM耦合数值模拟。加热和水化测试的模拟拟合了测得的温度，水含量和进水数据，并再现了地球化学数据的趋势。尽管测试的模拟结果显示出相似的趋势，但由于几何形状以及初始和限制条件，它们显示出差异。由于矿物溶解/沉淀引起的孔隙率变化在这些测试中无关紧要，但在长期模拟中却变得有意义，这表明腐蚀产物的沉淀显着降低了罐附近膨润土的孔隙率，并导致孔堵塞。膨润土蚀变带的厚度模拟为在1 Ma后小于7 cm。