地基液化区域桥梁抗震性能研究及数值分析

发布时间：2018-01-15 19:45

本文关键词：地基液化区域桥梁抗震性能研究及数值分析　出处：《长安大学》2014年硕士论文　论文类型：学位论文

【摘要】：震害调查结果表明，场地液化导致的地面变形是引起桩基震害的重要原因。研究可液化场地中桩基础的破坏机理和规律对预防和减轻地震液化给桥梁带来的危害具有重要意义。本文基于有限差分法程序FLAC3D建立数值模型，研究了不同条件下，在地震的作用下的土体和桩基的动力响应规律。本文的主要研究工作如下： 1.基于FLAC3D程序（有限差分法），以PL-Finn模型来模拟饱和砂土在动力作用下的特性，实体单元模拟土体，pileSEL单元模拟桩基，，建立可液化场地桩-土-结构动力相互作用有限差分三维数值模型。通过模型体系的动力特性的分析以及与振动台试验的对比，验证数值模型的正确性和可靠性； 2.利用FLAC3D进行单桩的分析计算，得出了桩在可液化地基中的反应规律：桩基内力在液化土层的交界处最大；探讨了上覆非液化土层、覆盖层密实度、上部结构的重量以及桩底的支承形式等因素对桩在动力作用下响应的影响。计算分析结果表明，覆盖层减弱了桩结构的地震响应，上部结构的重量和桩底的支承形式分别对桩的上部、下部响应影响较为显著； 3.讨论了群桩和单桩内力分布的不同，以及高桩承台和低承台形式下桩内力分布的规律； 4.探讨了碎石桩和刚性排水桩对液化场地的影响，及孔压比沿深度的分布规律。分析结果表明，这两种排水桩能够显著提高场地的抗液化性能；讨论了在桩径确定时，桩间距对提高其抗液化性能的影响。
[Abstract]:The results of the earthquake disaster investigation show that. Ground deformation caused by site liquefaction is an important cause of earthquake damage of pile foundation. It is of great significance to study the failure mechanism and law of pile foundation in liquefiable site to prevent and reduce the damage to bridge caused by earthquake liquefaction. The numerical model is established based on the finite difference method program FLAC3D. The dynamic response of soil and pile foundation under different conditions is studied. The main work of this paper is as follows: 1. Based on the FLAC3D program (finite difference method), the PL-Finn model is used to simulate the dynamic behavior of saturated sand, and the solid element is used to simulate the soil. The finite difference finite difference numerical model of pile-soil-structure dynamic interaction in liquefiable site is established by pileSEL element simulation. The dynamic characteristics of the model system are analyzed and compared with the shaking table test. Verify the correctness and reliability of the numerical model; 2. Using FLAC3D to analyze and calculate single pile, the response law of pile in liquefiable foundation is obtained: the internal force of pile foundation is the largest at the junction of liquefaction soil; The effects of overlying non-liquefaction soil layer, overburden compactness, weight of superstructure and supporting form of pile bottom on the dynamic response of pile are discussed. The overburden weakens the seismic response of the pile structure, and the weight of the superstructure and the supporting form of the bottom of the pile have a significant effect on the upper part and the lower part of the pile respectively. 3. The difference of internal force distribution between group pile and single pile is discussed, and the law of pile internal force distribution under the form of high pile cap and low pile cap is discussed. 4. The influence of gravel pile and rigid drainage pile on liquefaction site and the distribution of pore pressure ratio along the depth are discussed. The results show that the two drainage piles can improve the liquefaction resistance of the site. The influence of pile spacing on the improvement of liquefaction resistance is discussed when the diameter of pile is determined.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3

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