In recent decades, the deformation of soils induced by temperature variations has received increasing attention due to the limited understanding of its governing mechanisms and variables, and the rising significance of such phenomenon for science and engineering. This paper provides new competence on this subject, with a focus on coarse-grained soils. Specifically, this work presents experimental laboratory investigations and discrete element simulations addressing the thermally induced deformation of coarse-grained soils at different length scales. For the first time, the influence of relative density is studied considering minimal levels of applied vertical stress. The results show expansive deformation of coarse-grained soils upon heating and contractive deformation upon cooling for all relative densities. The magnitude of the contraction is more significant than the expansion, leading to a residual contractive deformation over one heating-cooling cycle. Microscopic insights drawn from numerical simulations highlight an increase in grain rearrangement through inter-particle sliding during both heating and cooling. These results also show that denser soils exhibit larger heating expansion and particle sliding, corroborating the existence of expansive grain rearrangement that can be linked to a mobilisation of dilatancy arising from thermally induced deviatoric stress.

中文翻译：

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垂直应力几乎为零的粗粒土的热致变形

近几十年来，由于对土壤的控制机理和变量的了解有限，并且这种现象对科学和工程的重要性日益提高，由温度变化引起的土壤变形受到越来越多的关注。本文提供了关于该主题的新功能，重点是粗粒土壤。具体来说，这项工作提出了实验性实验室研究和离散元模拟，以解决不同长度尺度下粗粒土的热致变形。第一次，在最小水平施加垂直应力的情况下研究了相对密度的影响。结果表明，在所有相对密度下，粗粒土在加热时的膨胀变形和冷却时的收缩变形。收缩的幅度大于膨胀的幅度，导致在一个加热-冷却循环中残留的收缩变形。从数值模拟中获得的微观见解突出了在加热和冷却过程中，由于颗粒间的滑动，晶粒重排的增加。这些结果还表明，较稠密的土壤表现出较大的热膨胀和颗粒滑动，从而证实了膨胀晶粒重排的存在，该重排可以与由热诱发的偏应力引起的剪胀动员有关。