Sand-EPS geofoam is commonly used as a seismic buffer in a variety of geotechnical applications to alleviate damages imposed by seismic vibrations. Evaluation of the properties of the sand-EPS geofoam interface is an essential part of the design and installation of EPS geofoam in direct contact with the parent sand. In this study, a series of laboratory tests are carried out using a large-scale direct shear apparatus to evaluate the monotonic, cyclic and post-cyclic behavior of the sand-EPS geofoam interface. Adopting the relative density of the parent sand, the density of EPS geofoam, the applied normal stress, the cyclic shear strain semi-amplitude and the number of cycles as the variable parameters, their influence on the response of the sand-EPS geofoam interface is investigated. According to the experimental results, with the increase in the number of cycles, sand relative density, EPS geofoam density and the applied normal stress, the equivalent or secant stiffness of the sand-EPS geofoam interface increases while its damping ratio declines. The results of the monotonic (MDS) and post-cyclic monotonic (CMDS) shearing experiments also show that with an increase in the EPS density and normal stress, which offers greater resistance against sliding, the mobilized shear stresses generally increase.

中文翻译：

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砂-EPS土工泡沫界面的单调、循环和后循环剪切行为

砂 EPS 土工泡沫通常用作各种岩土工程应用中的地震缓冲器，以减轻地震振动造成的损坏。沙土-EPS 土工泡沫界面的性能评估是设计和安装与母砂直接接触的 EPS 土工泡沫的重要组成部分。在这项研究中，使用大型直剪设备进行了一系列实验室测试，以评估砂 - EPS 土工泡沫界面的单调、循环和后循环行为。以母砂相对密度、EPS土工泡沫密度、外加法向应力、循环剪应变半振幅和循环次数为变量参数，它们对砂-EPS土工泡沫界面响应的影响为调查。根据实验结果，随着循环次数、砂相对密度、EPS土工泡沫密度和外加法向应力的增加，砂-EPS土工泡沫界面的等效或割线刚度增加，而其阻尼比下降。单调 (MDS) 和后循环单调 (CMDS) 剪切实验的结果还表明，随着 EPS 密度和法向应力的增加（提供更大的滑动阻力），动员剪切应力通常会增加。