Shaft friction degradation in geotechnical problems occurs alongside large uncertainties. Under cyclic loadings, offshore foundations can episodically suffer the loss of stiffness and strength. In such cases, initial in-situ soil state is lost as soil is disturbed during cyclic loading. In this sense, it is important to develop a testing procedure to assess the lateral friction degradation. Considering that a cone is a miniature driven pile, the use of this testing technique allows monitoring the degradation of sleeve friction during cyclic loading. This paper aims to improve the knowledge on the feasibility of using cone testing for the recognition of lateral friction degradation of a dry granular soil. Cyclic mCPT tests were performed in a calibration chamber considering a range of loading conditions. The effect of cyclic displacement amplitude and the confining pressure were investigated. Lateral friction, f_s, degrades while repeating the load cycling, resulting in loss of lateral strength due to soil-cone interface friction degradation. After about ten load cycles, degradation tended to stabilize for all tests.

中文翻译：

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干燥颗粒土壤中循环 mCPT 的性能：实验方法

岩土工程问题中的轴摩擦退化伴随着很大的不确定性发生。在循环载荷下，海上基础可能会偶尔遭受刚度和强度的损失。在这种情况下，由于土壤在循环加载期间受到干扰，初始原位土壤状态会丢失。从这个意义上说，开发一个测试程序来评估横向摩擦退化是很重要的。考虑到锥体是一个微型打入桩，使用这种测试技术可以监测循环加载过程中套筒摩擦的退化。本文旨在提高有关使用锥形测试识别干粒状土壤横向摩擦退化的可行性的知识。考虑到一系列负载条件，在校准室中进行循环 mCPT 测试。研究了循环位移幅值和围压的影响。横向摩擦力，f_s，在重复载荷循环时退化，由于土锥界面摩擦退化导致横向强度损失。在大约十个负载循环之后，所有测试的退化趋于稳定。