桩撑支护深基坑大变形固结有限元分析

发布时间：2018-04-22 19:48

本文选题：桩撑支护结构 + 大变形　；参考：《广东工业大学》2013年硕士论文

【摘要】：我国城市建设过程中土体开挖对周围环境的不利影响和引起的公共危害问题日益突出,如广州等沿海沿江地区普遍存在大范围的深厚软黏土,在这些地区进行新(扩)建公路或铁路、基坑开挖、工业和民用建筑地基处理的时候,通常会遇到开挖土体发生大变形从而影响原有支护结构安全的情况。随着广州轨道交通、地下空间建设的加速,对地下工程的安全与设计也提出了更高要求。本文在分析研究大变形的相关资料和前人研究成果的基础上,对平面梁单元的修正拉格朗日描述(Updated Lagrangian,简称U.L.描述)以及完全拉格朗目描述(Total Lagrangian,简称T.L.描述)的表达式进行推导,并运用大型通用有限元软件ABAQUS对桩撑支护结构进行大变形有限元分析。本文的主要研究内容包括： (1)阐述广州地区软土的分布特点和工程特点,总结广州地区软土的物理、力学性能指标,为ABAQUS数值模拟中的模型参数选取提供参考依据和对照。 (2)阐述基坑大变形分析的基础理论、U.L.描述的Biot固结理论以及桩撑支护结构中支撑杆单元的U.L.和T.L.的有限元的矩阵表达式,最后推导了把桩作为平面梁单元的U.L.和T.L.描述下的有限元矩阵表达式。 (3)介绍了ABAQUS软件及其在岩土工程中的应用,简要讨论了弹性模型(线弹性模型、多孔介质模型,邓肯-张模型)和塑性模型(莫尔-库仑模型,修正剑桥模型)的适应范围和条件,并对某基坑算例采用不同的模型(线弹性模型、邓肯-张模型、莫尔库仑模型以及修正剑桥模型)进行大小变形分析,着重对四者的大小变形的特点和差异性进行研究。 (4)将某基坑算例的简化三维模型的大变形分析计算结果与典型平面应变模型的分析计算结果进行对比分析,验证采用简化三维模型分析的可靠性。采用简化三维模型对某基坑算例进行考虑渗流作用的大变形分析,主要分析了桩撑支护基坑在土体开挖过程中的位移场分布、孔压分布和支护桩弯矩变化规律,探讨了桩撑支护基坑开挖过程中的时间效应,最后分析土体的渗透系数、土中有无渗流以及支撑材料类型对桩撑支护基坑性状的影响。 (5)对某工程实例进行考虑渗流作用的大变形分析,并与小变形分析进行对比,之后将两种分析计算结果与实测值进行对比。本文最后总结研究成果,得出有关结论,提出自己在研究过程中的不足和问题,指出今后有待进一步研究的问题,在此基础上对以后的研究进行展望。
[Abstract]:In the process of urban construction in our country , the adverse effects of soil excavation on the surrounding environment and the problems of public hazard caused by soil excavation are becoming more and more serious , such as the large - scale deep soft clay in the coastal areas such as Guangzhou .

( 1 ) The distribution characteristics and engineering characteristics of soft soil in Guangzhou area are expounded , and the physical and mechanical properties indexes of soft soil in Guangzhou area are summarized . The reference basis and control are provided for the selection of model parameters in numerical simulation .

( 2 ) The basic theory of large deformation analysis of foundation pit , U . L . ' s consolidation theory and the matrix expression of U . L . and T . L . of the supporting rod unit in pile support structure are described . Finally , the finite element matrix expression under the description of U . L . and T.L . of the plane beam unit is deduced .

( 3 ) In this paper , the adaptive scope and condition of elastic model ( linear elastic model , porous media model , Duncan - Chang model ) and plastic model ( Mol - Coulomb model , modified Cambridge model ) are introduced briefly . The deformation analysis of the size and deformation of some foundation pit is studied by using different models ( linear elastic model , Duncan - Chang model , Morkulm model and modified Cambridge model ) .

( 4 ) The calculation results of the simplified three - dimensional model of a foundation pit are compared with those of the typical plane strain model , and the reliability of the analysis is verified by using the simplified three - dimensional model .

( 5 ) A large deformation analysis considering the seepage effect is carried out for an engineering case , and compared with the small deformation analysis , then two kinds of analysis results are compared with the measured values .

In the end , the thesis summarizes the research results , draws some conclusions , points out the shortcomings and problems in the course of the research , points out the problems to be further studied in the future , and looks forward to the future research .

【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.2

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