The behaviour of piles subjected to lateral loads has been explored by a number of investigators over the past five decades. However, the vast majority of the previous literature has ignored the potential influence of additional torsional effects due to horizontal eccentricities of the applied lateral loads. In this paper, an upper bound mechanism and a lower bound stress field are presented for the calculation of the ultimate combined torsional and lateral loads on single piles in clay. The corresponding analytical upper and lower bound plasticity solutions are shown to be in excellent agreement, bracketing the theoretically exact failure loads with an error of less than 0·5%. Two-dimensional finite-element analyses are also presented and the computed ultimate loads and observed failure mechanisms are shown to compare very well with the plasticity solutions. Based on the numerical results and analytical solutions, failure load interaction diagrams and a simple empirical equation are presented that allow the calculation of the lateral bearing capacity factor for any level of applied torsion and pile–soil adhesion factor. It is demonstrated that the effect of torsion can be very significant, causing reduction in lateral bearing capacity of up to 50% and therefore should be considered in design.

中文翻译：

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扭转对黏土桩不排水极限侧向阻力的影响

在过去的五十年中，许多研究人员已经探讨了承受侧向载荷的桩的行为。然而，由于施加的水平载荷的水平偏心，绝大多数先前的文献都忽略了附加扭转效应的潜在影响。本文提出了一个上限机制和一个下限应力场，用于计算黏土中单桩的极限组合扭转和横向载荷。相应的分析上限和下限可塑性解显示出极好的一致性，将理论上精确的破坏载荷括起来，误差小于0.5％。还进行了二维有限元分析，并显示了计算的极限载荷和观察到的破坏机理，与塑性解决方案具有很好的比较。根据数值结果和解析解，给出了破坏荷载相互作用图和一个简单的经验方程式，可以计算出任意水平的施加扭转力和桩土黏附系数的侧向承载力系数。事实证明，扭转的影响可能非常显着，导致横向承载力降低多达50％，因此在设计中应予以考虑。给出了破坏荷载相互作用图和一个简单的经验公式，可以计算出任意水平的施加扭转和桩-土附着力因子的侧向承载力因子。事实证明，扭转的影响可能非常显着，导致横向承载力降低多达50％，因此在设计中应予以考虑。给出了破坏荷载相互作用图和一个简单的经验公式，可以计算出任意水平的施加扭转和桩-土附着力因子的侧向承载力因子。事实证明，扭转的影响可能非常显着，导致横向承载力降低多达50％，因此在设计中应予以考虑。