Abstract A parametric study on the long-term deformations of monopile foundations for offshore wind turbines is presented. The finite element calculations of a monopile in fine sand were performed with a high-cycle accumulation (HCA) model. The results are analyzed with respect to the horizontal displacements, the tilting of the pile head, settlement of the ground surface and effective stress changes in the surrounding soil. The dimensions of the pile (diameter, length of embedding, wall thickness), the initial density of the sand and the cyclic loading (average value, amplitude, lever arm) have been varied. The influence of the drainage conditions (either fully drained or partially drained) is also discussed. The validity of Miner’s rule is checked for both types of drainage conditions. Furthermore, the effect of changes of the direction of the cycles and of a multidimensional cyclic loading is addressed. The interesting phenomenon of a “self-healing”, i.e. a re-erection of the deformed monopile after a storm event, is demonstrated based on simulations with small cycles following a large preloading. Simulations with homogeneous and stochastically fluctuating fields of void ratio are compared.

中文翻译：

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海上风力发电机单桩基础长期变形的高周累积模型研究

摘要 提出了海上风力发电机单桩基础长期变形的参数研究。细砂中单桩的有限元计算采用高循环堆积 (HCA) 模型进行。分析了水平位移、桩头倾斜、地表沉降和周围土壤有效应力变化的结果。桩的尺寸（直径、嵌入长度、壁厚）、沙子的初始密度和循环载荷（平均值、振幅、杠杆臂）已经改变。还讨论了排水条件（完全排水或部分排水）的影响。对两种类型的排水条件都检查了 Miner 规则的有效性。此外，解决了循环方向变化和多维循环加载的影响。“自我修复”的有趣现象，即风暴事件后变形单桩的重新竖立，是基于大预加载后小循环的模拟来证明的。比较了具有均匀和随机波动的空隙率场的模拟。