砂土中水平循环荷载下单桩式海上风电体系自振频率偏移规律  

Frequency shift of monopile supported wind power turbine under lateral cyclic loading in sand

作　　者：王洋[1,2] 龚维明 竺明星[3] 戴国亮 万志辉[1,2] WANG Yang;GONG Weiming;ZHU Mingxing;DAI Guoliang;WAN Zhihui(Key Laboratory of C&PC Structures,Ministry of Education,Southeast University,Nanjing 211189,China;School of Civil Engineering,Southeast University,Nanjing 211189,China;School of Civil Engineering and Architecture,Jiangsu University of Science and Technology,Zhenjiang 212003,China)

机构地区：[1]东南大学混凝土及预应力混凝土结构教育部重点实验室,江苏南京211189 [2]东南大学土木工程学院,江苏南京211189 [3]江苏科技大学土木工程与建筑学院,江苏镇江212003

出　　处：《中南大学学报（自然科学版）》2022年第11期4372-4380,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(52078128,51808112,51878160);江苏省自然科学基金资助项目(20180155,20200675)。

摘　　要：提出循环荷载下单桩式风机体系自振频率偏移的理论评估方法。首先,考虑沉陷坑与致密域土体质量守恒原则,量化由循环荷载引起的土体参数变化;然后,基于刚性桩极限平衡理论,建立考虑桩端阻力的桩头三弹簧刚度矩阵;最后,在考虑桩头三弹簧自振频率评估框架的基础上,对循环荷载引起的自振频率偏移规律进行研究。研究结果表明:土体越疏松、桩基长细比越小,循环荷载对结构体系自振频率的影响越显著;而随着循环沉陷、致密的进程,自振频率的偏移率会有所降低。体系自振频率的偏移量和偏移方向与桩土相对刚度有关,在循环荷载作用下,完全刚性桩的自振频率表现出增大趋势,增幅可达3倍以上,设计时需慎重考虑;而半刚性桩体系在循环荷载作用下自振频率有所减小,减小量在5%以内。The theoretical evaluation method of natural frequency shift of monopile supported OWT system under cyclic loading was proposed.Considering the mass conservation principle of subsidence pit and densified soil,the variation of soil parameters caused by cyclic loading was quantified.Based on the limit equilibrium theory of rigid pile,the stiffness matrix of pile head considering the lateral resistance of pile tip was established.Based on the existing natural frequency evaluation method,the natural frequency shift caused by loading cycles was studied.The results show that the smaller the relative density of soil and the smaller the slenderness ratio of pile,the more significant the influence of cyclic loading on the natural frequency shift of the structure system is.However,with the process of soil subsidence and densification during loading cycles,the offset rate of natural frequency will decrease.The offset and shift trends of natural frequency are related to the pile-soil relative stiffness.For the perfectly rigid pile,the natural frequency increases obviously under the cyclic loading,and the increasement rate may be over three times,which should be carefully considered in the design.However,the natural frequency of semi-rigid pile decreases by less than 5%under cyclic loading.

关 键 词：循环荷载 单桩 砂土 自振频率 偏移 

分 类 号：TU473[建筑科学—结构工程]