桥梁基桩的屈曲及其可靠度分析方法分析.docx

摘 要
\J随着我国大跨度桥梁的高速发展,超长、超高的桥梁基桩在工程建设中应用 f“益广泛,因此桥梁基桩的屈曲分析也日益受到应有的重视。基桩的屈曲分析是一个相当复杂而又具有实际工程意义的课题,其影响因素繁多。尽管国内外学者上世纪就已有相应的探讨,取得了许多研究成果,但大多局限于对基桩本身的屈曲研究,而未考虑基桩本身的初始弯曲、施工缺陷和土体分层等诸多特殊情况的影响。结构可靠度设计是近年来才提出的基于概率论的设计方法,由于桩土共同工作珥桩基的结构体系和设计计算体系十分复杂,各种土性的取值因为样本空fsJ 的非常庞大而难以准确确定,因此离实际应用尚存在一定问题,而对基桩屈曲的可靠度分析目前似尚未见文献报道。通过对桥梁基桩屈曲破坏机理的深入分析, 客观地评价了国内外基桩屈曲的各种分析方法,讨论了诸如桩身初始倾斜、初始弯曲、初始倾斜以及分层地基等特殊环境对基桩屈曲的影响;给出了多种边界条件下基桩屈曲分析的能量法解答及其幂级数解的思路,提出了基桩屈曲分析的非线性有限元方法,并利用大型有限元结构分析软件ANSYS实现了桥梁基桩届曲分析的非线性分析;完成了对桥梁基桩在初始倾斜、初始弯曲、初始缺陷及分层地基情况下的非线性屈曲分析,得出一些可用于指导工程实践的重要结论;提出了基桩屈曲的可靠度分析思想,采用贝叶斯方法对基桩屈曲极限荷载的概率分布进行修正,引用模糊随机可靠度的验算点法计算基桩的屈曲可靠度,利用蒙特卡洛模拟求解基桩屈曲极限荷载随机变量的统计特征值,提出了几种计算基桩屈曲可靠度指标的方法,从而实现了基桩屈曲的可靠度分析:将本文方法用于已有模型实测资料及大型现场实桩实测资料的分析,其表明本文方法计算结果与实测值吻合良好。
关辚倦浆、腓可靠墩牝有限元
ABSTRACT
With the great development of brides with large—scale span in China, the application of superlong and superhigh bridge pile in construction is increasingly popular,SO that the bridge-pile buckling analysis(hereafter abbreviated as BPB Analysis)gradually receives its due a practically significant topic on project,the BPB Analysis influenced by many factors is scholars at home and abroad had made corresponding research during the last century and at the same time they had made great achievements,most of them confine themselves to the research on perfect pile buckling,not considering the influence of
many special situations such as the initial bend,the defects in construction
and the layered soil,etc The reliabiliW design has not been advanced according to the design method of probability theory until recent years.
For the cooperation of pile—soil,plicacy of the structure system and
the design and calculation system of the pile foundation,and further more for it's difficult to determine the properties of various kinds of soil due to the large scope of samples,there are still some problems in real the way it seems there iS no document or report about the reliability analysis of pile buckin