Investigations on the drift of piles subjected to cyclic lateral loading with a changing loading direction and on the reduction of the drift

桩的循环横向荷载将导致桩的位移和旋转的累积。如果在循环加载期间载荷改变其方向，则累积可以加速。这样的负载情况将发生，即来自离岸平台上的风和波浪负载。初步研究和项目第一阶段的结果表明，积累有所增加。主要进行了1g和ng模型试验。第二个项目阶段将对漂移现象使用不同的方法。将使用有限元法（FEM）和单元试验（改变剪切方向的简单剪切试验）进行数值研究。它们将补充以前的测试方案，并将允许对结果进行更广泛的解释。简单剪切试验将桩结果与土壤记忆问题更紧密地联系起来。这些实验室试验的数值模拟将证明有限元和本构模型的能力，相对于复杂的加载历史和加载路径。此外，原型将与有限元模拟，以评估该方法的能力。将考虑孔隙比的空间变异性，以模拟实际条件。这种土壤固有的各向异性可能有助于产生不平行于加载方向的桩位移，从而重现模型试验的结果。

Cyclic lateral loading of a pile will result in an accumulation of displacement and rotation of the pile. The accumulation can accelerate, if the load is changing its direction during the cyclic loading. Such a loading situation will occur i.e. from wind and wave loading on an offshore monopile. Preliminary studies and the results from the first project stage have shown an increased accumulation. Here, mainly 1g and ng model tests were performed. The second project stage is going to use a different approach on the drift phenomenon. Numerical studies using the finite element method (FEM) and element tests (simple shear tests with changing shearing direction) will be performed. They will complement the previous testing programme and will allow a wider interpretation of the results. The simple shear testing will link the pile results more closely to the question of the memory of the soil. The numerical simulation of these laboratory tests will prove the capability of the FEM and the constitutive model with respect to complex loading histories and loading paths. Furthermore, a prototype will be simulated with the FEM to evaluate the methods capabilities. The spatial variability of the void ratio will be considered to model realistic conditions. This soil inherent anisotropy might help to produce pile displacements that are non-parallel to the loading direction and thus reproduce the results from the model tests.