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中文题名:

 

考虑不确定性的近海钢管桩承载及变形特性研究

    

姓名:

 刘卓文    

学号:

 1049721803179    

保密级别:

 公开    

论文语种:

 chi    

学科代码:

 081402    

学科名称:

 工学 - 土木工程 - 结构工程    

学生类型:

 硕士    

学位:

 工学硕士    

学校:

 武汉理工大学    

院系:

 土木工程与建筑学院    

专业:

 土木工程    

研究方向:

 近海桩承载力    

第一导师姓名:

 陈波    

第一导师院系:

 武汉理工大学    

第二导师姓名:

 徐东升    

完成日期:

 2021-03-31    

答辩日期:

 2021-05-21    

中文关键词:

 

近海钢管桩 ; 桩承载力 ; 贝叶斯方法 ; 土塞效应 ; PLAXIS 3D模拟

    

中文摘要:

随着海上风电的大力发展,大直径管桩越来越多的应用于风电桩基,复杂海洋环境和岩土体参数使得单桩承载力预测较为困难。利用现场静力触探测试(CPT)数据推测桩基承载力是国内外规范中的常用方法,然而,在海洋环境下,由于成本和条件的制约,现场CPT数据较为缺乏,如何利用有限的CPT测试数据来预测桩基承载力是迫切需要解决的难题。针对上述难题,本文分析了影响大直径钢管桩承载力的因素,如桩周土体参数、桩-土相互作用系数、土塞效应等,建立了贝叶斯的不确定分析模型;基于现场桩基承载力试验数据,构建了三维随机有限元模型,分析了桩土相互作用机理,并提出了基于CPT数据的近海桩竖向承载力计算方法。本文的主要研究工作如下:

(1)探讨了单桩竖向承载力的不确定性来源和有效数据带来的计算误差,在此基础上,基于33根桩竖向承载力测试数据,利用贝叶斯概率理论,结合先验信息和现场CPT数据,对竖向承载力的不确定性进行定量分析;通过马尔科夫链式循环和蒙特卡洛随机抽样方法,生成竖向承载力的等效样本;根据对等效样本的统计分析,讨论了测量参数不确定性对竖向承载力的影响。

(2)基于响水风电场项目现场桩基测试结果,讨论了钢管桩内部土塞对竖向承载力的影响,分析钢管桩内部土体的土层分布不确定性;并对内侧摩阻力进行量化分析,将CPT预测桩基承载力方法进行了修正,并与国内外规范中计算方法进行对比,结果表明:修正后的方法预测的竖向承载力误差在0.4%~5.3%之间,误差远低于规范中的方法,且实测结果均位于修正后计算结果的90%置信区间之内。

(3)规范中桩侧摩阻力系数k为固定值,然而在海洋环境下,桩侧土体属性变化较大,基于固定系数k计算桩基竖向承载力会带来较大的误差。因此,基于随机有限元方法,建立响水风电场桩基的三维随机场模型,研究了土体参数空间变异性对桩基承载力的影响;并基于模型分析结果,提出了k系数的计算公式,由计算结果可知随深度变化,k系数在4 ~ 13之间波动,且在不同区域内的k系数的变化规律存在一致性。

(4)基于随机有限元模型,对桩-土之间荷载传递规律进行分析,探讨了桩-土沉降变形机理;对水平静载作用下的P ~ y曲线进行分析,并提出桩侧土体弹性系数kpy的计算方法,由计算结果可知,kpy随着土体的影响区域范围的增大而降低,随着土体弹性模量的增大而上升;同时,kpy的理论计算值与实际P ~ y曲线斜率有相同的变化趋势,能准确地对测试桩P ~ y曲线进行预测。

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中图分类号:

 TU473.1    

条码号:

 002000062422    

馆藏号:

 TD10050536    

馆藏位置:

 403    

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 403-西院分馆博硕论文库;203-余家头分馆博硕论文库    

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