The majority of wind turbine foundations consist of hollow monopiles inserted in the soil, requiring high computational effort to be numerically simulated. Alternative simplified models are very often employed instead. Three-dimensional solid models, in which the hollow structure and pile are substituted by solid cylinders with equivalent properties, are the most extended simplifications. Very few 2D models can be found in the literature due to the challenge of finding suitable equivalent properties and loads to fully represent the 3D nature of the problem. So far, very limited attention has been devoted to the accuracy of both 3D and 2D simplified models under dynamic and even static actions. Thus, in this paper, simplified 3D and 2D solid models are proposed and justified. An elasto-plastic constitutive model with accumulative degradation is used to simulate the soil behaviour, and frictional contact elements are implemented between the soil and pile to model their interaction. These simplified approaches are compared with the full 3D hollow model, under static and cyclic loads. The results demonstrate that the proposed simplified approaches are a reasonable alternative to the 3D hollow model, which allows researchers and designers to drastically reduce the computational effort in the simulations under long term conditions.

中文翻译：

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模拟空心单桩风力涡轮机基础的简化数值模型

大多数风力发电机基础由插入土壤中的空心单桩组成，需要大量的计算工作才能进行数值模拟。替代的简化模型经常被代替使用。三维实体模型是最广泛的简化方法，其中空心结构和桩被具有相同特性的实体圆柱代替。由于难以找到合适的等效属性和载荷来完全表示问题的3D性质，因此在文献中几乎找不到2D模型。到目前为止，在动态甚至静态动作下，对3D和2D简化模型的准确性的关注都非常有限。因此，本文提出并证明了简化的3D和2D实体模型。利用累积退化的弹塑性本构模型来模拟土的行为，并在土与桩之间建立摩擦接触单元以模拟它们之间的相互作用。将这些简化方法与静态和循环载荷下的完整3D空心模型进行比较。结果表明，所提出的简化方法是3D空心模型的合理替代方案，它使研究人员和设计人员可以大幅度减少长期条件下仿真中的计算量。