Abstract The ultimate shaft capacity of pile foundations in frozen grounds has long been correlated to the long-term shear strength of the surrounding frozen soils using a surficial roughness factor “m”. This roughness factor is different for different pile materials (e.g., steel, concrete, and timber), but is often assumed to be constant for any soil type, ground temperature, or stress condition. The current study evaluates the validity of the proposed roughness factor “m” for steel piles embedded in frozen clay and exposed to different scenarios of ground temperatures and normal stress levels. Interface element tests were utilized to characterize the shear strength of frozen Leda clay and the adfreeze strength of the pile-frozen clay interface and to investigate the proposed roughness factor “m” for steel piles exposed to various temperatures and normal stress conditions. The experiments were carried out in a walk-in temperature-controlled environmental chamber. Roughness factor “m” was found not to be a constant number for a given pile material, but rather to decrease with an increase in the freezing temperature. A frictional factor “n”, analogous to roughness factor “m”, was also introduced to correlate the frictional resistance of frozen soil to the frictional resistance of the pile-soil interface. A temperature-dependent empirical equation was also proposed for predicting the shaft capacity of steel piles based on the shear strength parameters of the surrounding ice-rich clay soil.

中文翻译：

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不同暴露温度下冻结粘土中钢桩的界面剪切强度特性

摘要 长期以来，冻土中桩基的极限承载力与周围冻土的长期抗剪强度相关，使用表面粗糙度系数“m”。对于不同的桩材料（例如钢、混凝土和木材），该粗糙度系数是不同的，但通常假设对于任何土壤类型、地温或应力条件都是恒定的。目前的研究评估了建议的粗糙度系数“m”对于嵌入冻结粘土中并暴露于不同地温和法向应力水平的钢桩的有效性。界面单元测试被用来表征冷冻 Leda 粘土的剪切强度和桩-冷冻粘土界面的抗冻强度，并研究暴露于各种温度和正应力条件下钢桩的建议粗糙度系数“m”。实验在步入式温控环境室中进行。发现粗糙度系数“m”对于给定的桩材料不是一个常数，而是随着冻结温度的增加而降低。还引入了摩擦系数“n”，类似于粗糙度系数“m”，用于将冻土的摩擦阻力与桩土界面的摩擦阻力相关联。