Abstract

The piles of offshore wind turbines are always subjected to multidirectional loads. The vertical and lateral behaviours of piles are designed separately in practice. However, many studies have shown that the vertical load has a substantial influence on the lateral behaviours of piles. The influence of the vertical load on the lateral behaviours of monopiles can be divided into three aspects: (1) the influence of the friction stress on the ultimate resistance p_u of the p-y curve, (2) the P-Δ effect, and (3) the M_R effect induced by the uneven distribution of vertical skin friction. Based on the passive wedge theory and the influence of the ultimate soil resistance per unit length p_u caused by the vertical loads, the corrected p-y curve for sand is obtained. Considering the P-Δ effect and M_R effect, an analytical method for monopiles under combined loads, including the lateral load, vertical load and moment, in sand is proposed based on the elastic-foundation beam theory coupled with p-y curves. The method is verified by analysing several existing cases. The capability of the proposed method to reasonably calculate the responses of monopiles under multidirectional loads in sand has been verified.

摘要

海上风力涡轮机的桩总是受到多向载荷。在实践中，桩的竖向和横向行为是分开设计的。然而，许多研究表明，竖向荷载对桩的横向性能有很大的影响。竖向荷载对单桩侧向性能的影响可分为三个方面：（1）摩擦应力对p - y曲线的极限阻力_pu的影响，（2） P- Δ效应， (3)垂直表面摩擦分布不均匀引起的MR效应_。基于被动楔理论和单位长度极限土阻力的影响p _u由垂直载荷引起，得到校正的沙子p - y曲线。考虑P- Δ效应和M _R效应，基于弹性地基梁理论结合py曲线，提出了一种单桩在砂中组合荷载作用下的分析方法，包括横向荷载、竖向荷载和弯矩。通过分析几个现有案例验证了该方法。验证了所提方法在沙地多向荷载作用下合理计算单桩响应的能力。