摘要
海上风机系统长期承受风荷载、波浪等循环荷载作用,这种低频长期荷载作用下的桩—土相互作用,使桩周土体刚度发生变化,导致桩基累积变形增大,从而危及风机系统的运行安全。根据饱和砂土室内循环剪切试验得到刚度衰减规律并嵌入FLAC3D有限差分平台,建立海上风电系统三维桩—土相互作用数值模型。研究结果表明,桩基水平位移累积速率随荷载幅值的增大而增加;在相同无量纲荷载幅值下,随桩径的增大和场地密实度的降低而增加;桩基转动中心随桩径的增大呈现下移趋势,基本不受荷载大小与场地密实度的影响;通过整体数值模型分析发现,从桩基累积变形的长期发展来看,幂函数模型的预测结果更为可靠,两种预测模型的参数随荷载幅值、桩径的增大而增加,随场地土体密实度的增加而减小。
Offshore wind turbine system is hit by cyclic loads such as wind and wave,which causes the variation of soil stiffness around pile and the accumulated deformation of pile.These actions of cyclic loads even endanger the safe operation of offshore wind turbine.In this study,a numerical model is developed to analyze the cyclic deformation of offshore monopile by using FLAC3D.Based on the results of cyclic shear tests the degradation stiffness of soil is considered in this developed numerical model.This numerical model is used to obtain the influence of amplitude for cyclic loading and sand relative density and pile diameter on accumulated deformation of monopile,and the applicability of the existed predicted methods for accumulated deformation(power function method and logarithmic function method)are evaluated.The results show that the accumulation rate of pile displacement increases as the load amplitude increase,under the same dimensionless load amplitude,it increases with the increase of pile diameter and the density of sand increases.The rotation point of the pile tends to move downward with the increasing diameter and is less affected by load amplitude and sand density.Through the analysis of the whole numerical model,it is found that the power function method are more reliable in terms of the long-term development of pile accumulation deformation.The parameters of the two prediction methods increase as the load amplitude and diameter increase,while decreases as the density of sand increases.
作者
杨钰荣
孙毅龙
许成顺
翟恩地
YANG Yurong;SUN Yilong;XU Chengshun;ZHAI Endi(Laboratory of Urban Security and Disaster Engineering,Beijing University of Technology,Beijing 100124,China;College of Civil Engineering and Architecture,Wenzhou University,Wenzhou 325035,China;Goldwind Sci and Tech Co.,Ltd,Beijing 100176,China)
出处
《海洋技术学报》
2022年第4期79-95,共17页
Journal of Ocean Technology
基金
国家自然科学基金优秀青年基金项目(51722801)。
关键词
海上风电
单桩基础
刚度衰减
长期荷载
数值模拟
offshore wind power
monopile foundation
degradation stiffness model
long-term load
numerical simulation
