径向非均质土中桩—土纵向耦合振动动力响应研究

发布时间：2018-06-28 05:12

本文选题：三维轴对称 + 纵向振动　；参考：《大连海事大学》2017年硕士论文

【摘要】：本文分析了径向非均质土中纵向振动荷载作用下桩的动力响应问题。基于土体与桩的本构关系,文中采用三维轴对称土模型,较系统的考虑了桩周土竖向波动效应,建立径向非均质土体的三维波动方程和一维粘弹性桩的波动方程,再引入桩-土边界条件和接触条件,用解析法求解了粘弹性实体桩和管桩在纵向任意激振力作用下的耦合振动问题,主要研究工作包括:1.在考虑土体径向非均质性情况下,利用三维轴对称土体模型,采用分离变量法和超越方程求根法求得实体桩与土体接触界面的复刚度,进而推导得到单桩桩顶受任意纵向激振力作用下的桩振动方程的频域表达式,再利用卷积公式和拉普拉斯逆变换得到半正弦脉冲激励作用下桩顶速度时域响应半解析解。基于所得解对桩土耦合振动的机理以及土体动力反应特性进行研究,重点研究了土体的径向非均质性对桩-土动力特性的影响。研究表明,土体的径向非均质性对桩-土动力特性有着明显的影响,考虑土体径向非均质性十分必要。2.在轴对称条件下利用三维连续介质理论研究径向非均质土中管桩-土的纵向耦合振动问题。对桩周土任意圈层的平衡方程由外而内逐层求解,求得桩周土与桩接触界面所在圈层的位移表达式,再根据桩芯土动力平衡方程和边界条件求得桩芯土的位移表达式,进而利用管桩-土接触界面完全耦合条件求解桩动力平衡方程,得到桩顶的频域响应解析解和时域响应半解析解,并采用MATLAB软件编程,得到桩顶复刚度、桩顶速度导纳曲线、桩底反射波曲线,再通过变化土体、管桩特性参数,分析管桩内外半径比、长径比、土质扰动程度、扰动范围、圈层数变化等参数对管桩纵向振动特性的影响。本文给出的桩-土纵向耦合振动理论使桩基振动理论更为完善,也为桩基抗震,防震设计及桩基动态检测技术提供了更多理论支持。
[Abstract]:In this paper, the dynamic response of pile under longitudinal vibration load in radial heterogeneous soil is analyzed. Based on the constitutive relation between soil and pile, the three-dimensional axisymmetric soil model is used to systematically consider the vertical wave effect of soil around the pile, and the three-dimensional wave equation of radial heterogeneous soil and the wave equation of one-dimensional viscoelastic pile are established. By introducing pile-soil boundary condition and contact condition, the coupled vibration problem of viscoelastic solid pile and pipe pile under the action of longitudinal arbitrary excitation force is solved by analytical method. The main research work includes: 1. Considering the radial heterogeneity of soil mass, the complex stiffness of contact interface between solid pile and soil is obtained by using three-dimensional axisymmetric soil model, the method of separating variables and the method of root finding by transcendental equation. Furthermore, the frequency domain expression of the pile vibration equation under arbitrary longitudinal excitation on the top of a single pile is derived, and the semi-analytical solution of the velocity response in time domain is obtained by using convolution formula and Laplace inverse transformation. Based on the results, the mechanism of pile-soil coupling vibration and soil dynamic response were studied, and the influence of soil radial heterogeneity on pile-soil dynamic characteristics was studied. The results show that the radial heterogeneity of soil has obvious influence on the dynamic characteristics of pile-soil, and it is necessary to consider the radial heterogeneity of soil. The longitudinal coupling vibration of pipe pile-soil in radial heterogeneous soil is studied by using three-dimensional continuum theory under the condition of axisymmetric. In this paper, the equilibrium equation of any circular layer around the pile is solved layer by layer from outside to inside, and the displacement expression of the contact layer between the pile and the pile is obtained, and the displacement expression of the pile core soil is obtained according to the dynamic equilibrium equation of the pile core soil and the boundary condition. Then the dynamic equilibrium equation of the pile is solved by using the complete coupling condition between the pipe pile and the soil contact interface, and the analytic solution of the frequency domain response and the semi-analytical solution of the time domain response of the pile top are obtained, and the complex stiffness of the pile top and the velocity admittance curve of the pile top are obtained by using MATLAB software. By changing the soil mass and the characteristic parameters of the pipe pile, the influence of the parameters such as the ratio of the inside and outside radius of the pipe pile, the ratio of length to diameter, the degree of soil disturbance, the range of disturbance and the number of circles on the longitudinal vibration characteristics of the pile is analyzed. The pile-soil longitudinal coupling vibration theory presented in this paper makes the pile foundation vibration theory more perfect, and provides more theoretical support for the pile foundation seismic resistance, anti-seismic design and pile foundation dynamic detection technology.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

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