考虑冲刷情况下海上风电单桩基础优化设计研究

Study on the Optimum Geometry of Offshore Wind Turbine Monopiles Unprotected against Scour

冲刷是海上风电单桩基础设计中需要经常面对的问题,工程中一般采用冲刷保护装置或增加桩长来抵抗冲刷。但简单增加桩长是否经济合理,目前缺乏足够的研究分析。鉴于此,文中建立了考虑冲刷情况下海上风电单桩基础的优化设计模型,其中桩周土冲刷深度和范围以及桩-土相互作用根据DNV规范的公式进行计算。在优化过程中,以单桩基础最小重量为优化目标,以桩身强度和桩端转角为约束条件,以桩径、壁厚和桩长为优化参数,采用ANSYS APDL中OPTYPE的FIRST优化算法。并针对一实际工程案例,完成考虑冲刷和不考虑冲刷情况的优化设计。研究结果表明考虑冲刷发生情况下,适当增加桩径和壁厚比直接增加桩长更经济合理。

Based Scour is one of the most important problems in the design of monopile for offshore wind power exploitation. The scour protection device or pile length is usually used to resist scour. But even if simply increasing the length of pile is economical and reasonable, there is a lack of adequate research and analysis. Consequently, an optimal design model of monopile is established for offshore wind power under consideration of scour conditions, in which the scour depth, the range of surrounding soil and interaction between pile and soil are determined according to the relevant codes. In the optimization process, the minimum weight of the monopile is taken as the optimization objective, the pile strength and the pile end angle as the constraints, and the pile diameter, the wall thickness and the pile length are viewed as optimization parameters. This paper adopts the FIRST optimization algorithm of OPTYPE in ANSYS. According to a practical engineering case, an optimal design considering scour and no scour is completed. The results show that the increase of pile diameter and wall thickness ratio will be more economical and reasonable to increase the length of pile under the condition of scouring.