Abstract The effect of freeze-thaw (F-T) cycles on dynamic behavior of coarse-grained materials (CGMs) (i.e., coarse-grained materials used in railway subgrade named as base course materials) is critical to ensure the service status of railway subgrade in seasonally frozen regions. In this study, a series of stress-controlled dynamic triaxial tests were conducted on CGMs with various fines contents (FCs) exposed to F-T cycles. Typical test results were then analysed and discussed, highlighting the environmental effect on the dynamic properties. The results demonstrated that the dynamic shear modulus decreased with the increase of FC or the number of freeze-thaw cycles (NFT), but the damping ratio (D) results indicated just the reverse characteristic. In this regard, a modified empirical model was determined to describe the relationship between dynamic shear modulus (Gd) and dynamic shear strain amplitude ( γ ¯ d ). Meanwhile, a unified mathematical formula was proposed to characterize D. Furthermore, the two proposed empirical equations were found to be severely inconsistent with the previous ranges suit for seismic loading. The study provides a useful reference for preliminary evaluation of the response to train loading for CGMs subjected to F-T cycles.

中文翻译：

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不同细粒含量粗粒材料在多级动态载荷下冻融循环后的动态行为：实验研究和经验模型

摘要 冻融 (FT) 循环对粗粒材料 (CGM)（即铁路路基中使用的粗粒材料称为基层材料）动态行为的影响对于确保铁路路基的使用状态至关重要。季节性冰冻地区。在这项研究中，对暴露于 FT 循环的具有各种细粉含量 (FC) 的 CGM 进行了一系列应力控制动态三轴试验。然后分析和讨论了典型的测试结果，突出了环境对动态特性的影响。结果表明，动态剪切模量随着 FC 或冻融循环次数 (NFT) 的增加而降低，但阻尼比 (D) 结果表明正好相反。在这方面，确定了一个改进的经验模型来描述动态剪切模量 (Gd) 和动态剪切应变幅度 (γ¯ d ) 之间的关系。同时，提出了一个统一的数学公式来表征D。此外，发现这两个经验方程与先前的地震加载范围严重不一致。该研究为初步评估受 FT 循环的 CGM 对列车载荷的响应提供了有用的参考。