Abstract This study investigates the influence of freeze-thaw (FT) cycles on the (i) microstructure, (ii) soil water characteristics, and (iii) sensitivity of the volumetric strain and mechanical properties to moisture content for a compacted clay. The mechanical properties herein include resilient modulus (MR), unconfined compression strength (qu), and reloading modulus (E1%) and stress (Su1%) at 1% strain. Specimens were compacted at optimum moisture content and subjected to different FT cycles (i.e. 0, 1, 3, and 10 cycles). Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were performed to reveal the evolution of the microstructure during FT cycles. Specimens were then wetted or dried to different suction (s) and degree of saturation (Sr) values to obtain the (i) soil water characteristics using filter paper method and (ii) MR, qu, E1%, and Su1% using cyclic and static triaxial tests. Experimental results demonstrate that FT cycles induce cracks that are tens of microns in dimension, which reduce specimens' water retention capacity and the volumetric strain upon wetting and drying. Mechanical properties also reduce significantly and become less sensitive to the s and Sr after FT cycles. A model was used to predict the variation of the MR, qu, E1% and Su1% with s and Sr for specimens subjected to different FT cycles. An attenuation coefficient χFT was proposed to describe the FT-induced degradation in the qu, E1%, Su1%, and MR. It was found that the χFT for different mechanical properties are consistent. The evolution of their χFT with FT cycles can be described by a uniform empirical equation. The study presented in this paper is useful for the rational understanding and prediction of the hydromechanical behaviors of compacted clay taking account of the influence of FT cycles.

中文翻译：

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冻融循环对压实粘土湿度敏感性的影响

摘要 本研究调查了冻融 (FT) 循环对压实粘土的 (i) 微观结构、(ii) 土壤水分特性和 (iii) 体积应变和机械特性对含水量的敏感性的影响。此处的机械性能包括弹性模量 (MR)、无侧限压缩强度 (qu) 和再加载模量 (E1%) 和 1% 应变下的应力 (Su1%)。试样在最佳水分含量下压实，并进行不同的 FT 循环（即 0、1、3 和 10 次循环）。进行扫描电子显微镜 (SEM) 和压汞孔隙率 (MIP) 以揭示 FT 循环过程中微观结构的演变。然后将样品润湿或干燥至不同的吸力 (s) 和饱和度 (Sr) 值，以获得 (i) 使用滤纸法的土壤水分特征和 (ii) MR、qu、E1% 和 Su1%，使用循环和静态三轴试验。实验结果表明，FT 循环会导致尺寸为数十微米的裂纹，这会降低试样的保水能力和润湿和干燥时的体积应变。机械性能也显着降低，并且在 FT 循环后对 s 和 Sr 变得不那么敏感。模型用于预测经受不同 FT 循环的试样的 MR、qu、E1% 和 Su1% 随 s 和 Sr 的变化。提出了衰减系数 χFT 来描述 qu、E1%、Su1% 和 MR 中 FT 引起的退化。发现不同机械性能的χFT是一致的。它们的 χFT 随 FT 循环的演变可以通过统一的经验方程来描述。考虑到 FT 循环的影响，本文提出的研究有助于合理理解和预测压实粘土的流体力学行为。