Currently, inconclusive evidence characterizes the thermally induced deformation of sands. In this context, the role of the transient nature of heat diffusion on the thermally induced deformation of sands has remained largely disregarded. This paper presents a theoretical and computational investigation of the transient dynamics characterizing the thermally induced deformation of sands under oedometric conditions. The study shows that heating rates determined by the pore fluid pressure dissipation timescale to ensure drained conditions can cause an important temperature nonuniformity and a breakdown of quasi-static conditions. Under these dynamic conditions, the differential expansion between the sand and the confining oedometer ring uniquely characterizes the response and is broken down into two characteristic regimes. For slow heating rates and low-expansion ring materials, a mathematical analysis shows that expansion and only expansion can occur, regardless of relative density and stress level. For fast heating rates and high-expansion ring materials, a parametric analysis establishes the possibility of a very small initial volumetric contraction for loose materials under high stress levels. In the light of the existing literature, the study shows that the intrinsic volumetric response to heating loads of sand, as a material, is only expansive; volumetric contraction may only be observed under transient conditions. This work supports a conceptual shift in the framework of analysis of thermally induced deformation of sands, from a temperature-dependent material response to a rate-dependent response of a finite volume under nonuniform conditions.

中文翻译：

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砂体热致变形的瞬态动力学

目前，尚无定论的证据表明砂的热致变形。在这种情况下，热扩散的瞬态性质对砂的热致变形的作用在很大程度上仍然被忽视。本文介绍了在测压条件下表征砂的热致变形的瞬态动力学的理论和计算研究。研究表明，由孔隙流体压力耗散时间尺度确定的加热速率以确保排水条件可能会导致重要的温度不均匀性和准静态条件的崩溃。在这些动态条件下，沙子和围压计环之间的差异膨胀独特地表征了响应，并分为两个特征区域。对于慢速加热和低膨胀环材料，数学分析表明，无论相对密度和应力水平如何，都会发生膨胀并且只会发生膨胀。对于快速加热速率和高膨胀环材料，参数分析确定了松散材料在高应力水平下的初始体积收缩非常小的可能性。根据现有文献，该研究表明，作为一种材料，沙子对热负荷的固有体积响应只是广泛的；体积收缩只能在瞬态条件下观察到。这项工作支持砂子热致变形分析框架的概念转变，从温度相关的材料响应到非均匀条件下有限体积的速率相关响应。