海上风机变径单桩基础竖向承载特性及变径参数影响研究

Research on Vertical Bearing Characteristics and Influence of Correlation Parameters of Variable Diameter Monopile Foundation for Offshore Wind Turbine

为适应施工与承载能力要求,海上风机单桩基础常采用桩身变径措施,变径段可能会对桩基竖向承载特性产生影响。采用有限元分析软件ABAQUS建立变径桩数值模型,开展变径单桩竖向承载性能的数值模拟研究,并分析其尺寸参数对竖向承载能力的影响。计算结果表明:与通长桩相比,变径特性基本不影响其桩身轴力分布;随着竖向荷载增加,两类桩各承载分量占比首先保持不变,随后外侧摩阻力占比下降,内侧摩阻力和桩端阻力占比增加;增大变径桩底部桩径能有效提高桩基竖向承载力,且提高外侧摩阻力承载占比;增大变径段上部长度和变径段长度对桩基竖向极限承载力无明显影响,但会导致外侧摩阻力占比降低和内侧摩阻力占比提高。

In order to meet the requirements of construction and bearing capacity, the measure of the variable diameter of the pile body is often used for the monopile foundation of offshore wind turbines, and the variable diameter section may have an impact on the vertical bearing characteristics of pile foundation. A numerical model of a variable diameter monopile was established by the finite element analysis software ABAQUS, and a series of numerical simulations on the vertical bearing performance of variable diameter monopiles and the influence of their size parameters on the vertical bearing capacity were carried out. The numerical analysis results show that the variable diameter characteristics have little influence on the axial force distribution of the pile compared with the pile with the same diameter. With the increase of vertical load, the proportion of each bearing component of the two types of monopiles remains unchanged at first, and then the proportion of external side friction resistance decreases, while the proportion of internal side friction resistance and pile tip resistance increases. Increasing pile diameter at bottom of variable diameter pile can effectively improve the vertical bearing capacity and increase the proportion of the external side friction resistance. Increasing the upper length and the length of the variable diameter section has no obvious effect on the vertical ultimate bearing capacity of the pile foundation, but will lead to the decrease of the proportion of the external side friction resistance and the increase of the proportion of the internal side friction resistance.