海上风电大直径单桩基础固有频率影响因素的数值分析

针对海上风电整机结构其低阶固有频率的控制问题,基于有限元分析技术开展小直径桩土相互作用的数值模拟分析,与试验结果、API规范计算结果进行对比,验证了数值模型的适用性,分析大直径单桩结构桩内土芯、冲刷深度、表层土置换措施对整机固有频率的影响,结果表明,基于有限元实体单元计算所得一、二阶整机固有频率要明显大于传统p-y方法计算结果;桩内土芯对一、二阶整机固有频率影响很小;在一定范围内,随着泥面冲刷深度的增加,一、二阶固有频率降低不明显,认为传统p-y方法对于大直径单桩的适用性有待研究;在实际工程设计中,桩内土芯的影响可忽略;对于大直径单桩,在一定范围内可以忽略冲刷的影响。

Numerical Analysis of Influencing Factors on Natural Frequency of Large-diameter Single Pile Foundation of Offshore Wind Power

Aiming at the low-order natural frequency control problem of offshore wind turbine structure,the small diameter pile-soil interaction was numerically simulated by FEM.Comparison of the numerical results with the experimental results and that of API regulation verify the applicability of the numerical model.The effects of soil core,scouring depth and surface soil replacement measures on natural frequency for the large diameter single pile was studied.The results show that the natural frequencies of the first and second-order complete machines by FEM based on solid elements are significantly greater than those calculated by the traditional p-y method;the soil core in the pile has little effect on the low order natural frequencies;within a certain range,the increasing of the scour does not lead to the sharp decline of the first and second order natural frequencies.The applicability of the traditional p-y method to large-diameter single piles needs to be further investigated;in practical engineering design,the influence of soil core in the pile can be ignored;for large-diameter single piles,the impact of scour can be ignored within a certain range.