饱和土中大直径桩纵向振动研究

发布时间：2018-05-22 16:53

本文选题：大直径桩 + 横向惯性效应　；参考：《苏州科技大学》2017年硕士论文

【摘要】：在我国的长江三角洲、珠江三角洲等沿海地区,有着很高的人口密度并伴随着众多的大型建筑工程。在这些地区,海拔较低,河网纵横,土质松软,地下水位较高,含水量较大,所以在这些地区大直径桩基更是被大量地采用。而目前对于饱和土中大直径桩基的纵向振动研究还不充足,因此本文以理论分析为主,建立了均质饱和土中、成层饱和土中桩-土耦合振动模型,并结合桩-土振动模型试验验证了理论模型的正确性。论文的主要内容有以下几个方面:(1)基于饱和多孔介质理论和Novak薄层法,将桩视为Rayleigh-Love杆,采用粘弹性桩底支承,分别建立均质饱和土中、成层饱和土中桩-土耦合作用模型并求解,推导出桩顶复刚度、桩顶导纳、桩顶速度时域响应的表达式,分析水的体积分数、横向惯性效应、脉冲宽度、桩基长径比、桩侧土体软(硬)夹层及软(硬)夹层厚度、桩身缺陷(缩颈和扩颈)程度及缺陷长度等因素对桩顶动力响应的影响,并将干土和饱和土中的桩顶动力响应进行对比。(2)基于饱和多孔介质理论和Novak薄层法,采用扩散虚土桩法桩底支承,建立基于虚土桩支承的成层饱和土中桩-土耦合作用模型,求出桩顶动力响应的表达式,分析虚土桩扩散角、嵌岩桩桩底沉渣厚度、桩侧土剪切波速不同时持力层软硬对桩顶动力响应的影响。(3)对不同桩径以及不同材质的模型桩进行低应变桩基动测试验,从试验的角度验证桩径、桩的材质、桩土模量比对桩顶速度时域响应曲线的影响,并结合桩-土振动模型试验,进行理论结果与试验结果的拟合分析,验证基于虚土桩支承的饱和土中大直径桩基纵向振动理论的合理性。
[Abstract]:In China's Yangtze River Delta, Pearl River Delta and other coastal areas, there is a high population density and accompanied by a large number of large construction projects. In these areas, the elevation is low, the river network is vertical and horizontal, the soil is soft, the groundwater level is high and the water content is large, so the large diameter pile foundation is used in these areas. At present, the longitudinal vibration of large diameter pile foundation in saturated soil is not enough, so the model of pile-soil coupling vibration in homogeneous saturated soil and layered saturated soil is established in this paper, which is mainly based on theoretical analysis. The correctness of the theoretical model is verified by pile-soil vibration model test. The main contents of this paper are as follows: (1) based on the theory of saturated porous media and Novak thin-layer method, the pile is regarded as a Rayleigh-Love rod, and the viscoelastic pile bottom is used to support the homogeneous saturated soil. The model of pile-soil coupling in layered saturated soil is solved, and the expressions of pile top complex stiffness, pile top admittance, pile top velocity response in time domain are derived, and the volume fraction of water, transverse inertia effect, pulse width and ratio of length to diameter of pile foundation are analyzed. The influence of soft (hard) and soft (hard) interlayer thickness on the dynamic response of pile top, such as the thickness of soft (hard) interlayer, the degree of pile body defect (necking and necking) and the length of defect, etc. Based on the theory of saturated porous media and Novak thin layer method, the pile-soil coupling model in layered saturated soil is established by using diffusion virtual soil pile method to support the pile bottom, and the pile top dynamic response in dry soil and saturated soil is compared. The expression of the dynamic response of the pile top is obtained, and the diffusion angle of the dummy soil pile and the sediment thickness at the bottom of the rock-socketed pile are analyzed. The influence of soft and hard layer on dynamic response of pile top with different shear wave velocities of pile side soil. (3) dynamic test of low strain pile foundation with different pile diameters and model piles of different materials are carried out. The pile diameter and pile material are verified from the point of view of test. The influence of pile-soil modulus ratio on the time-domain response curve of pile top velocities is analyzed. Combining with pile-soil vibration model test, the theoretical and experimental results are fitted and analyzed. The theory of longitudinal vibration of large diameter pile foundation in saturated soil based on virtual soil pile support is verified.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

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