基于三维连续介质土模型的大直径桩纵向振动研究

发布时间：2018-05-18 03:23

本文选题：三维波动效应 + 大直径桩　；参考：《苏州科技大学》2017年硕士论文

【摘要】：为顺应建设事业的快速发展,建筑物的上部结构对桩基础承载力及变形能力的要求越来越高,因此桩基础呈现出向大直径桩发展的趋势。但由于大直径桩身尺寸的特殊性,其力学计算也较为复杂。相比普通桩型,对于三维连续介质土模型下的大直径桩的纵向振动动力特性研究则比较匮乏。在理论方面,对三维连续介质土模型下的大直径桩的桩身、桩侧土与桩身的相互关系、桩端土对桩身的支承作用做了简化模型的处理,采用解析方法较系统地分别对均质地基、径向非均质地基及改变桩底支承为虚土桩法三种情况下的大直径桩的桩-土耦合纵向振动问题进行研究;在试验方面,进行了室内模拟桩试验,将试验数据结果与上述研究的理论模型数据进行对比,分析基于三维连续介质土模型下大直径纵向振动理论的可行性。本论文具体研究内容可分为以下几个方面:(1)基于土体三维波动效应和大直径桩Rayleigh-love杆模型,将桩侧土体视为均质情况,桩底假设为弹性支承,结合定解条件,建立桩-土耦合振动理论解析解。研究大直径桩身考虑横向惯性效应的必要性及桩身参数——桩径、桩身泊松比对桩顶振动特性的影响。(2)考虑大直径桩成桩引起的施工效应,利用圈层间力与位移的连续条件通过函数正交性递推,建立径向非均质状态下的大直径桩桩顶动力响应的理论解。分别研究在桩侧土质硬化或软化情况下,相关特质参数——施工扰动范围及径向土体划分圈层数、扰动程度的变化对桩顶振动特性的影响。(3)改变桩底支承模型为虚土桩模型,通过积分变换及阻抗递推得桩顶频域解析解和时域半解析解。根据所得理论解,研究虚土桩参数——虚土桩划分精度、虚土桩长及虚土桩剪切波速对桩顶振动特性的影响,证明虚土桩法的合理性。(4)利用低应变无线基桩动测仪测得模型桩的桩顶速度时域曲线,通过改变模型桩径及模型桩材质,将理论与试验曲线进行拟合。达到验证理论模型正确性的目的。(5)对本文的上述研究成果进行总结,并对土体三维波动效应下的大直径桩纵向耦合振动的后续研究提出展望。
[Abstract]:In order to comply with the rapid development of construction, the superstructure of the building requires more and more high bearing capacity and deformation ability of pile foundation, so the pile foundation has a tendency to develop to large diameter pile. However, due to the particularity of the size of large diameter pile, its mechanical calculation is more complicated. Compared with ordinary pile type, the longitudinal vibration dynamic characteristics of large diameter pile under three-dimensional continuum soil model are less studied. In theory, the relationship between pile body, pile side soil and pile body, and the supporting effect of pile end soil on pile body under three-dimensional continuum soil model are simplified, and the homogeneous foundation is systematically treated by analytic method. The pile-soil coupling longitudinal vibration of large diameter piles under the condition of radial heterogeneous foundation and changing the support of pile bottom to fictitious soil pile method is studied in this paper. The experimental data are compared with the theoretical model data, and the feasibility of large diameter longitudinal vibration theory based on 3D continuum soil model is analyzed. This paper can be divided into the following aspects: 1) based on the three-dimensional wave effect of soil and the Rayleigh-love rod model of large diameter pile, the soil on the side of the pile is regarded as homogeneous, the pile bottom is assumed to be elastic support, and the solution condition is combined. The analytical solution of pile-soil coupling vibration theory is established. This paper studies the necessity of considering the lateral inertia effect of large diameter pile body and the influence of pile body parameter-pile diameter, and the effect of Poisson's ratio of pile body on the vibration characteristics of pile top. 2) considering the construction effect caused by large diameter pile. By using the continuous condition of interlayer force and displacement, the theoretical solution of the dynamic response of large diameter pile top under the condition of radial heterogeneity is established by function orthogonality recursion. Under the condition of soil hardening or softening on the pile side, the influence of the variation of the disturbance degree on the vibration characteristics of the pile top and the influence of the variation of the disturbance degree on the vibration characteristics of the pile top are studied respectively, which changes the supporting model of the pile bottom to the fictitious soil pile model. The analytical solutions in frequency domain and semi-analytical solutions in time domain are obtained by integral transformation and impedance recursion. Based on the theoretical solutions, the effects of the parameters of the virtual soil pile, the partition accuracy of the virtual soil pile, the length of the virtual soil pile and the shear wave velocity of the virtual soil pile on the vibration characteristics of the pile top are studied. It is proved that the virtual soil pile method is reasonable. (4) the time-domain velocity curve of the model pile is obtained by using a low strain wireless pile dynamometer. The theoretical and experimental curves are fitted by changing the diameter of the model pile and the material of the model pile. In order to verify the correctness of the theoretical model, this paper summarizes the above research results, and puts forward a prospect for the further study of the longitudinal coupling vibration of large diameter piles under the three-dimensional wave effect of soil.
【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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