摘要
为研究地震激励下“单桩-沉箱基础”式海洋风机桩动力响应规律,采用分离相似设计方法,将原型整体系统分离为“风机机舱-桩体-砂土”3个次级子系统,根据子系统各自特性分别进行相似设计,开展了“单桩-沉箱基础”式海洋风机桩振动台模型试验。依托试验结果对模型箱柔性边界的边界效应、风机桩应变响应、加速度响应、动土压力响应、桩-土体系共振响应等展开了分析。结果表明:边壁柔性材料能较好地降低刚性箱带来的边界效应影响;应变响应自桩底到机舱逐渐减小,且由于桩-土相互作用,桩身应变衰减较大,上部结构应变衰减则较小;桩身加速度响应具有明显的加速度放大效应,最大放大系数可达2.27;桩周动土压力没有出现随埋深增加而增加的规律性递增,而是呈现部分区段增加、部分区段减小的规律性分布,且最大动土压力位于土下3/4桩深处;输入地震动的傅氏谱能量集中频率区间与桩-土自振的傅氏谱能量集中频率区间重叠越多、频率分布越密的地震波,与结构发生的共振响应越大。基于以上结论可知,设计“单桩-沉箱基础”式海洋风机桩时宜采用“下大上小”的变截面桩体结构。
To study the dynamic response law of offshore wind turbine piles with a caisson foundation under seismic excitation,a model of offshore wind turbine pile with wind turbine and caisson foundation was designed by adopting the separating similarity design method.The prototype system is divided into three sub-systems that are engine room-pile-sand,and the requirements of similarity design are realized according to the characteristics of the sub-systems.Through the shaking table tests,the boundary effect of the flexible boundary of model box,the strain response of pile,the acceleration responses,the dynamic earth pressure response,the resonant response of the pile-soil system were analyzed.It is found that the flexible material of the sidewall can better reduce the influence of the boundary effect.The strain response decreases gradually from the bottom to top of the structure,and due to the interaction of pile-soil systems,the strain decay rate of the pile body under the soil is large,while the strain decay rate of the superstructure above the soil is small.The acceleration response of the pile body above the soil surface has a large amplification effect,and the maximum amplification factor can reach 2.27.The dynamic earth pressure around the pile does not increase regularly with the increase of burial depth but shows a regular distribution of increasing in some sections and decreasing in some sections,and the maximum dynamic earth pressure is located at the depth of 3/4 of the pile under the soil.The more overlapping the Fourier spectrum energy concentration frequency range of the input ground motion and the pile-soil vibration Fourier spectrum energy concentration frequency range and the denser the frequency distribution,the greater the resonant response to the structure.According to these conclusions,it can be seen that the variable cross-section pile structure should be adopted in the design of an offshore wind turbine pile that has a caisson foundation.
作者
李胜民
王志佳
彭留留
郭士康
黎洪磊
崔洁
LI Shengmin;WANG Zhijia;PENG Liuliu;GUO Shikang;LI Honglei;CUI Jie(School of Civil Engineering,Hainan University,Haikou 570228,China;School of Civil Engineering,Chongqing University,Chongqing 400044,China;School of Information and Communication Engineering,Hainan University,Haikou 570228,China)
出处
《地震工程与工程振动》
CSCD
北大核心
2023年第1期221-228,共8页
Earthquake Engineering and Engineering Dynamics
基金
国家自然科学基金项目(51708163)
海南省自然科学基金项目(520MS018,2019RC113,522CXTD510)。
关键词
海洋风机桩
单桩-沉箱基础
振动台
边界效应
结构动力响应
offshore wind turbine pile
monopile-caisson foundation
shaking table
boundary condition effect
structural dynamic response
