Temperature changes are known to induce specific couplings in clay, in particular, an anomalously high thermal pressurization in undrained conditions or a thermal compaction in drained conditions, both of which are potential threats for the mechanical stability and sealing capacity of the geomaterials. Thermodynamical analysis of those peculiar thermomechanical couplings points to a potentially important latent energy, which in turn could limit the temperature change upon heating or cooling. The direct measurement of latent energy developed during a laboratory geomechanical test is challenging. Instead, proper identification of thermal hardening in conventional experiments with temperature changes provides an alternative route to estimate latent energy. In this work, existing laboratory thermomechanical tests of clays are analyzed with a rigorous thermodynamic framework to quantify the magnitude of latent energy in thermomechanically loaded clays. A thermodynamically consistent constitutive model for fully saturated clays that combines two key features, (a) the temperature dependence of the blocked energy and (b) the framework of bounding plasticity, is proposed. The performance of the model is validated by reproducing results obtained in laboratory tests for Boom and Opalinus clays. The thermomechanical loads considered to validate the model performance were then used to estimate the percentage of work that remains latent in the clayey material during plastic yielding. We find that the magnitude of latent energy is quite significant, typically a few tens of percent of the total dissipated energy, and increases significantly with temperature. Accordingly, it is expected to play an important role in the thermomechanical response of clays.

中文翻译：

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热加载粘土中潜热的大小

已知温度变化会引起粘土中的特定耦合，特别是在不排水条件下异常高的热压或在排水条件下的热压实，这两者都是对土工材料的机械稳定性和密封能力的潜在威胁。这些特殊的热机械耦合的热力学分析指出了潜在的潜在潜能，而潜能又可以限制加热或冷却时的温度变化。在实验室地质力学测试期间直接测量潜能的方法具有挑战性。取而代之的是，在常规实验中随着温度变化正确识别热硬化，可以提供另一种估算潜能的途径。在这项工作中 现有的实验室粘土热力学测试采用严格的热力学框架进行分析，以量化热机械负载粘土中的潜能大小。提出了结合两个关键特征的全饱和粘土的热力学一致本构模型，（a）结合能量的温度依赖性和（b）边界塑性的框架。该模型的性能通过重现在动臂和Opalinus粘土的实验室测试中获得的结果来验证。然后，考虑用来验证模型性能的热机械载荷来估算塑性屈服过程中留在黏性材料中的功的百分比。我们发现潜能的大小非常重要，通常占总耗散能量的百分之几十，并随温度显着增加。因此，期望在粘土的热机械响应中起重要作用。