The undrained bearing capacity of shallow circular piles in non‐homogeneous and anisotropic clay is investigated by the lower bound (LB) finite element limit analysis (FELA) under two‐dimensional (2D) axisymmetric condition using second‐order cone programming, and the new solution of the problem is presented. Modified from the isotropic von Mises yield criterion, a cross‐anisotropic undrained strength criterion of clays under the axisymmetric state of stress requiring three input shear strengths in triaxial compression, direct simple shear, and triaxial extension is employed in the 2D axisymmetric LB FELA. Parametric studies on the effects of pile embedment ratio, dimensionless strength gradient, anisotropic strength ratio, and pile roughness are investigated extensively, while the predicted failure mechanisms associated with these parameters are discussed and compared. Numerical results of undrained end bearing capacity of shallow circular piles are summarized in the form of design tables that are useful for design practice and represent a new contribution to the field of pile capacity considering the combined effects of undrained strength non‐homogeneity and anisotropy.

中文翻译：

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非均质和各向异性黏土中浅圆形桩端承力的不排水下界解

在二维（2D）轴对称条件下，使用二阶锥规划，通过下限（LB）有限元极限分析（FELA）研究了非均质各向异性粘土中浅层圆形桩的不排水承载力。提出了问题的解决方案。根据各向同性的冯·米塞斯屈服准则进行修改，在二维轴对称LB FELA中，采用了在轴对称应力状态下要求三输入抗剪强度，三阶直接剪切和三轴延伸的横各向异性各向异性不排水强度准则。广泛研究了桩的埋深比，无因次强度梯度，各向异性强度比和桩粗糙度的影响，同时讨论并比较了与这些参数相关的预测故障机制。以设计表的形式总结了浅圆桩不排水端承载力的数值结果，这对设计实践是有用的，考虑到不排水强度非均质性和各向异性的综合影响，这对桩容量领域做出了新的贡献。