冲刷对海上风电单桩基础自振频率影响的研究  

Effects of scour on the natural frequency of offshore wind turbine structures

作　　者：陈琛 马宏旺[1] 李玉韬 芦直跃 CHEN Chen;MA Hongwang;LI Yutao;LU Zhiyue(School of Naval Architecture,Ocean&Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学船舶海洋与建筑工程学院,上海200240

出　　处：《振动与冲击》2020年第22期16-22,共7页Journal of Vibration and Shock

基　　金：国家“973”基础研究资助项目(2014CB046200)。

摘　　要：目前海上风电基础形式大多采用单桩基础,海水的冲刷作用影响结构的动力特性和受力性能,其中自振频率受到的影响最为显著,因此,研究冲刷对海上风电单桩基础自振频率的影响十分必要。通过模型试验研究了冲刷深度、砂土密度和桩埋置深度对单桩基础自振频率的影响;利用ABAQUS软件建立了单桩基础的三维有限元模型,并通过与模型试验结果对比分析,验证数值模型的可靠性;以一实际工程为例,分析了补偿冲刷造成自振频率降低的各种措施。结果表明,随着冲刷深度的增加,单桩基础的自振频率会逐渐降低,其中砂土越松、埋置深度越浅,降低越明显;在相同用钢量的情况下,增加桩埋置深度、壁厚和桩径,都能增加结构自振频率,但增加桩径的效果最为明显;建议在实际工程设计中,可通过增加桩径来补偿由冲刷造成自振频率的降低以满足设计要求。The majority of offshore wind turbines(OWT)are supported by large diameter monopiles.Scour caused by seawater affects the dynamic characteristics and mechanical property of the wind turbine,and its impact on the structural natural frequency is especially significant.Therefore,it is necessary to study the effect of scour on the natural vibration frequency of OWT monopile foundations.First,the effects of scouring depth,sand density and pile embedding depth on the natural frequency of monopile foundations were studied by model test.Then,a three-dimensional finite element model of monopile was established by ABAQUS and the reliability of the numerical model was verified by comparison between the simulation results and model test results.Finally,taking a project as an example,a variety of measures to reduce the natural frequency caused by scour were analyzed.It is shown that,with the increase of scour depth,the natural frequency of the monopole foundation will gradually decrease,and the looser the sandy soil is and the shallower the embedded depth is,the more obvious the decrease is.With the same amount of steel consumption,increasing the embedded depth,wall thickness and pile diameter all can increase the natural frequency of the structure,but increasing the pile diameter has the most obvious effect.It is suggested that the decrease of natural frequency caused by scour can be compensated by increasing pile diameter in practical engineering design to meet the design requirements.

关 键 词：海上风机 单桩基础 冲刷 自振频率 ABAQUS 

分 类 号：P752[天文地球—海洋科学]