【作者】 张杰；

【导师】 孔德森； 戚庆学；

【作者基本信息】 山东科技大学 ， 建筑与土木工程（专业学位）， 2019， 硕士

【摘要】 风能是21世纪世界各国大力发展的绿色、可再生能源。我国近海风电资源十分丰富,海上风电事业发展迅速。其中超大直径单桩基础作为被最广泛应用的风机基础形式,具有极大的发展潜力和空间。超大直径单桩基础在服役期间受到风、浪等动荷载的共同作用,在此情况下对其进行瞬态动力学分析将具有明确桩基受荷性状、检验桩基稳定性和指导优化实际施工的重要意义。以江苏省如东县某近海区域的水位地质条件为基础,运用有限元模拟软件ABAQUS进行数值模拟,对波浪荷载单独作用及共同作用下的近海风电大直径单桩基础进行动力响应特性研究,并分析了在数值模型中不同因素对大直径单桩基础动力响应的影响,分析的影响因素有荷载大小、荷载位置、土体压缩模量、桩体自由度。通过影响因素的不同量值,得出近海风电大直径单桩基础动力特性的变化规律,从而为实际施工提供有价值的参考。得到以下研究结论:(1)以江苏省如东县海域为背景,对近海风电单桩基础结构进行适当简化,选择建立桩-土有限元模型,利用ABAQUS有限元数值模拟软件,建立近海风电单桩基础的有限元模型,对单桩基础做了模态分析,得出了结构前12阶模态振型。根据比较发现,单桩基础模态振型在频率范围内,固有频率比较类似,在数值上相差甚小。(2)对近海风电单桩基础在风浪荷载作用下进行的瞬态动力学分析,得到了关键部位的位移、应力、速度和加速度的极值以及其对应的动力响应时程曲线,其主要特征有两点:一是结构位移的最大值始终出现在单桩基础的桩顶;二是结构应力值最大的地方主要出现在桩身埋至15m位置处。(3)在拟静力算法中,将周期性的波浪荷载进行静力化,得到了结构拟静力荷载作用下近海风电单桩基础的位移和应力云图及极值。(4)通过改变荷载大小,荷载作用点位置及土体压缩模量,采用控制变量的方法对近海风电单桩基础的位移和应力进行对比分析并得到了以下主要结论,一是随着波浪荷载的增大,近海风电单桩基础表现的位移、应力、速度及加速度都会随之增大;二是波浪荷载作用点位置对近海风电单桩基础应力影响最大,其次是位移,速度和就加速度几乎没有影响;三是地基土压缩模量的增加,单桩基础关键部位的位移逐渐减小,桩顶表现最为明显,单桩基础关键部位的应力逐渐增大,埋深15m处表现最为突出。更多还原

【Abstract】 Wind energy is a green and renewable energy developed vigorously by all countries in the world in the 21st century.China is rich in offshore wind power resources,and offshore wind power industry is developing rapidly.As the most widely used fan foundation form,super-large diameter single pile foundation has great development potential and space.Super-large diameter single pile foundation is subjected to wind,wave and other dynamic loads during its service period.Under such circumstances,transient dynamic analysis of the pile foundation will be of great significance in determining the loading behavior of the pile foundation,checking the stability of the pile foundation and guiding the optimization of actual construction.Based on the water level and geological conditions of an offshore area in Rudong County,the finite element simulation software ABAQUS was used to carry out numerical simulation,The dynamic response characteristics of offshore wind power large diameter single pile foundation under wave loads and combined loads were studied.and the influence of different factors on the dynamic response of large diameter single pile foundation in the numerical model was analyzed.The influencing factors include load size,load location,compressive modulus of soil and degree of freedom of pile.The dynamic characteristics of offshore wind power large diameter single pile foundation were obtained by different magnitudes of influencing factors,which can provide valuable reference for practical construction.The following conclusions are drawn:(1)Taking the sea area of Rudong County as the background,the structure of offshore wind power single pile foundation is appropriately simplified,and the pile-soil finite element model is selected.The finite element model of offshore wind power single pile foundation is established by ABAQUS finite element numerical simulation software.The modal analysis of the single pile foundation is carried out,and the first 12 modal shapes of the structure are obtained.According to the comparison,it is found that the modal shapes of single pile foundation are within the frequency range,and the natural frequencies are similar,with little difference in numerical values.(2)The transient dynamic analysis of offshore wind power single pile foundation under wind wave load is carried out,and the extreme values of displacement,stress,velocity and acceleration of key parts and their corresponding dynamic response time history curves are obtained.The main characteristics are as follows:First,the maximum value of structural displacement always appears at the pile top of the single pile foundation;Second,the place where the structural stress value is the largest is mainly at the position where the pile body is buried to 15m.(3)In the pseudo-static algorithm,the wave load of Periodicity is staticized,and the displacement and stress nephogram and extreme value of offshore wind power pile foundation under the pseudo-static load are obtained.(4)The displacement and stress of offshore wind power single pile foundation are compared and analyzed by changing the load size,the position of load action point and the compression modulus of soil.The following main conclusions are obtained.First,the displacement,stress,velocity and acceleration of offshore wind power single pile foundation will increase with the increase of wave load.Secondly,the position of wave load action point has the greatest influence on the stress of offshore wind power pile foundation,followed by displacement,velocity and acceleration with little influence.Third,with the increase of the compressive modulus of the foundation soil,the displacement of the key parts of the single pile foundation gradually decreases,with the pile top showing the most obvious,the stress of the key parts of the single pile foundation gradually increases,with the most prominent performance at the depth of 15m.更多还原