近海风机桩基础地震作用和长期循环荷载作用下动态特性研究

发布时间：2018-04-18 06:30

  本文选题：近海风电 + 粘性土　； 参考：《西南交通大学》2014年硕士论文

【摘要】：随着传统化石能源对环境的影响日趋严重,风能作为新型可再生能源得到了广泛关注。其中,近海丰富的风能资源掀起了近海风电的发展热潮。单桩式基础是海洋风电最常采用的基础形式之一,国内外许多学者开展了其在海洋环境内荷载作用下的安全性研究。由于近海风机在全寿命期内可能要承受地震荷载、风浪荷载及机械振动等多种荷载作用,因而结构安全需要满足：1)风机整体结构自振周期在运营年限内避开叶片转动周期,避免产生共振；2)在外荷载作用下横向变形满足设计要求。本文主要研究了单桩式基础在地震荷载作用下和长期循环荷载作用下的动力特性。基于上海东海大桥风电场场地条件,选取了3种地震波并采用NERA软件分析了场地响应特性。采用El Naggar提出的计算方法,结合ABAQUS软件建立了非线性Winkler地基模型,计算了单桩式基础在地震作用下的横向变形特性。结合已有的试验资料,提出了我国沿海典型粘土的软化系数经验公式并建立了数据库。在此基础上,提出了新的粘性土刚度-阻尼退化模型,该模型采用修正弹簧-阻尼器并联元件实现。基于提出的退化模型建立计算模型,分析了单桩式基础在长期循环荷载下的自振频率和横向变形特性,并将计算结果与国内外学者提出的控制标准进行了对比。与规范的拟静力法相比,本文的计算方法可较好的考虑动力荷载的特性,并能较好的考虑长期荷载对结构的累积作用,可为以后的实际工程运用提供参考。
[Abstract]:With the increasing impact of traditional fossil energy on the environment, wind energy as a new renewable energy has been widely concerned.Among them, offshore abundant wind energy resources set off offshore wind power upsurge.Single pile foundation is one of the most commonly used foundation forms for offshore wind power. Many scholars at home and abroad have carried out research on its safety under the load in marine environment.Since offshore fans may have to bear various loads such as earthquake load, wind wave load and mechanical vibration during their lifetime, the structural safety needs to meet the requirement of 1: 1) the free vibration cycle of the whole structure of the fan should avoid the blade rotation cycle in its operating life.The transverse deformation under external load meets the design requirements.In this paper, the dynamic characteristics of single pile foundation under earthquake load and long term cyclic load are studied.Based on the site conditions of Shanghai Donghai Bridge wind farm, three kinds of seismic waves were selected and the site response characteristics were analyzed by NERA software.The nonlinear Winkler foundation model is established by using the calculation method proposed by El Naggar and the ABAQUS software. The transverse deformation characteristics of single pile foundation under earthquake action are calculated.Based on the available experimental data, an empirical formula for softening coefficient of typical coastal clay in China is put forward and a database is established.On this basis, a new stiffness-damping degradation model of cohesive soil is proposed, which is implemented by a modified spring-damper parallel element.Based on the proposed degradation model, the natural vibration frequency and transverse deformation characteristics of single pile foundation under long-term cyclic load are analyzed, and the calculation results are compared with the control standards proposed by domestic and foreign scholars.Compared with the quasi-static method of code, the calculation method in this paper can better consider the characteristics of dynamic load and the cumulative effect of long-term load on the structure, which can provide a reference for the practical application in the future.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU473.1
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本文编号：1767193