超长期循环荷载作用下海上风机大直径单桩动力特性演变规律研究  

Evolution of dynamic characteristics of large diameter monopile of offshore wind turbine under ultra-long term cyclic load

作　　者：龚敏[1] 朱涛 陈守祥[1] 张东明[1] 贺瑞[2] GONG Min;ZHU Tao;CHEN Shouxiang;ZHANG Dongming;HE Rui(Central Southern China Electric Power Design Institute Co.,Ltd.,China Power Engineering Consulting Group,Wuhan 430071,China;College of Harbour,Coastal and Offshore Engineering,Hohai University,Nanjing 210098,China)

机构地区：[1]中南电力设计院,武汉430071 [2]河海大学港口海岸与近海工程学院,南京210098

出　　处：《振动与冲击》2023年第1期259-266,共8页Journal of Vibration and Shock

基　　金：中国电力工程顾问集团中南电力设计院科研项目。

摘　　要：大直径单桩基础是目前应用最广泛的一种海上风机支撑结构,其现有相对成熟的研究主要集中在承载力、累积变形和初始动力特性计算等问题。而海上风机对海洋环境中的风、浪、流、地震波及其运行荷载等动荷载非常敏感,因此在长期循环荷载作用过程中,其振动特性变化规律必须得到充分研究。通过在干砂中对大直径单桩进行室内1 g模型试验,以模型桩承载力为参考值,施加相同频率、不同幅值的循环荷载,并在加载过程中进行频响分析,得到桩顶水平位移频响函数,进而得出了以下结论:(1)桩基一阶共振频率随循环次数增大而增大;(2)阻尼比随循环加载次数整体呈降低趋势;(3)桩顶刚度则受循环荷载的致密作用和振动坑的形成等多因素影响,割线刚度主要呈下降趋势,卸载刚度呈增大趋势。Large diameter monopile foundation is the most widely used offshore wind turbine support structure at present.The existing relatively mature study mainly focuses on load-bearing capacity,cumulative deformation and initial dynamic characteristics calculation.Offshore wind turbine is very sensitive to dynamic loads,such as,wind,wave,current,seismic wave and its operating load in marine environment,so its vibration characteristics must be fully studied in the process of long-term cyclic load.Here,through indoor 1 g model tests of large-diameter monopile in dry sand,taking load-bearing capacity of model pile as reference value,cyclic loads of the same frequency and different amplitudes were exerted and frequency response analysis was performed in loading process to obtain the frequency response function of horizontal displacement of pile top.The results showed that(1)the first-order resonance frequency of pile foundation increases with increase in number of cycles;(2)damping ratio decreases with cyclic loading times;(3)pile top stiffness is affected by many factors,such as,compaction of cyclic load and formation of vibration pit;secant stiffness mainly has a dropping trend,and unloading stiffness has an increasing trend.

关 键 词：海上风机 大直径单桩 室内模型试验 长期循环荷载 频响分析 共振频率 阻尼比 桩顶水平刚度 

分 类 号：TU473[建筑科学—结构工程]