海上风力机结构体系长期经受波浪、风等水平循环荷载的作用,循环荷载的长期作用会引起桩周地基土体产生棘轮效应及形成密实沉陷区,研究长期循环荷载效应对风力机单桩承载特性的影响规律具有重要的工程意义。基于有限差分软件FLAC3D计算平台,建立风力机单桩的数值计算模型,与既有桩基试验开展对比验证模型的有效性;随后引入长期循环荷载效应引起的桩周密实沉陷简化模型,开展海上风力机大直径单桩的承载性能对比研究,探讨考虑与未考虑密实沉陷区时桩基的变形、弯矩、p-y（土体抗力-桩基水平位移）曲线的差异,分析长期循环荷载效应对桩基承载特性的影响规律。结果表明,密实沉陷对单桩的刚性转动点位置基本无影响,但在桩基埋置的浅层区域,桩周密实沉陷区对桩基水平位移影响显著,且引起桩基弯矩发生突变。
Abstract
Offshore wind turbine structural system is usually struck by lateral cyclic loads such as wave and wind. Ratchet effect and a dense subsidence zone in the vicinity of offshore pile is caused by these dynamic cyclic loads. It is necessary that the influence of cyclic loads on bearing characteristics for offshore pile is revealed. Based on finite difference software FLAC3D calculation platform,a numerical calculation model of offshore monopile was established,and the reliability of this numerical model was verified by comparing with the existing pile tests. Then,a simplified model was used in this numerical model to simulate the dense subsidence zone caused by long-term effect of cyclic loads. A compared study between considering and no-considering a dense subsidence zone is conducted to present the difference of bearing performance. These differences of pile deformation,pile bending moment and p-y curve are discussed,and the influence law of long-term effect of cyclic loads on the bearing characteristics of monopole is analyzed. The results show that the dense subsidence zone has no effect on the position of the rigid rotation point of monopile. But the dense subsidence zone has a significant effect on the horizontal displacement of pile in the shallow buried area,and a sudden change of the bending moment for pile is caused.
关键词
海上风力机 /
循环荷载 /
桩基础 /
承载特性
Key words
offshore wind turbines /
cyclic loads /
pile foundation /
bearing capacity
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基金
中国博士后科学基金（2022M722960）; 浙江省自然科学基金（LQ23E090003）; 温州市科技计划（S2023001）
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