Because indentation tests which are used in several engineering fields allow obtaining material strength parameters in a fast, reliable and reproducible manner, the present study was initiated with the aim of finding out whether such tests could also be used in geotechnical engineering. Experimental results are obtained from undrained indentation tests performed with a rigid flat-tipped, cylindrical indenter on Champlain clay specimens in order to deduce values of elastic moduli and yield stresses. These values are compared to those deduced from unconfined compression tests. Results of an Arbitrary Lagrangian–Eulerian (ALE) based finite element analysis that simulates such test are also presented. It is assumed that the clay behaves as a linear-elastic, perfectly plastic material obeying von-Mises yield criterion. A frictionless contact interface is chosen to realistically model interactions on the indenter-clay, clay-platen and clay-ring interfaces. The paper presents distributions of contact pressures beneath the indenter and along lateral and lower boundaries. Typical contours of von Mises deviator stress and equivalent plastic strain corresponding to different indentation depths in the clay specimen are presented. It is also shown that the presence of hairline cracks on the clay along the perimeter of the indenter and the limited thickness of the sample affect the deduced values of Young’s modulus and yield stress.

中文翻译：

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平端轴对称压头对敏感黏土压痕的物理建模和拉格朗日-欧拉随机有限元分析

由于在多个工程领域中使用的压痕测试可以快速，可靠和可重现的方式获得材料强度参数，因此本研究的开始是为了确定这种测试是否也可以用于岩土工程中。实验结果是通过在尚普兰粘土试样上使用刚性的扁平尖头圆柱形压头进行不排水压痕测试得出的，目的是推导弹性模量和屈服应力。将这些值与从无限制压缩测试得出的值进行比较。还介绍了基于拉格朗日-欧拉（ALE）的任意有限元分析的结果，该结果模拟了这种测试。假定粘土遵循von-Mises屈服准则，表现为线弹性，完全塑性的材料。选择了无摩擦接触界面，以真实地模拟压头-粘土，粘土-压板和粘土-环界面上的相互作用。本文介绍了压头下方以及沿横向和下部边界的接触压力分布。给出了与粘土试样中不同压痕深度相对应的冯·米塞斯偏转应力和等效塑性应变的典型轮廓。还显示出沿着压头的周边在粘土上存在细线裂纹，并且样品的有限厚度影响了杨氏模量和屈服应力的推定值。给出了与粘土试样中不同压痕深度相对应的冯·米塞斯偏应力和等效塑性应变的典型轮廓。还显示出沿着压头的周边在粘土上存在细线裂纹，并且样品的有限厚度影响了杨氏模量和屈服应力的推定值。给出了与粘土试样中不同压痕深度相对应的冯·米塞斯偏转应力和等效塑性应变的典型轮廓。还显示出沿着压头的周边在粘土上存在细线裂纹，并且样品的有限厚度影响了杨氏模量和屈服应力的推定值。