Axisymmetrical Analytical Solution for Vertical Vibration of End-Bearing Pile in Saturated Viscoelastic Soil Layer
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摘要: 基于弹性和饱和多孔介质理论,将桩和饱和土层分别视为单相弹性介质和饱和粘弹性介质,利用Helmholtz分解和变量分离法,在频率域研究了饱和粘弹性土层中端承桩纵向振动的动力特性,给出了饱和粘弹性土层中桩纵向振动时动力响应的轴对称解析解及桩头复刚度的解析表达式.通过数值计算,给出了桩头动刚度因子和等效阻尼随激励频率的响应,考察了饱和土物性参数、桩土模量比、桩长径比、桩Poisson比等参数对桩头刚度因子和阻尼的影响.研究表明:由于考虑了桩的径向变形效应以及饱和粘弹性土层对桩的径向力作用,轴对称精确解的桩头动刚度因子和阻尼分别与经典Euler-Bernoulli杆模型桩的桩头动刚度因子和阻尼有较大的区别,特别是在若干激励频率处.因此,经典Euler-Bernoulli杆模型桩的适用性具有一定的局限,更加精确的分析应采用三维精确模型.Abstract: Based on the elasticity and theory of saturated porous media,regarding the pile and the soil as a single phase elastic medium and a saturated viscoelastic medium,respectively,the dyn amical behavior of vertical vibration of an end-bearing pile in a saturated viscoelastic soil layer was investigated in frequency domain with the Hemlho ltzdecom position and variable separation method.The axisymm etrical analytical solutions for vertical vibrations of the pile in a saturated viscoelastic soil layer were obtained,and the an alytical expression of the dynam ical complex stiffness of the pile top was presented.The responses of dynamic stiffness factor and equ ivalent damping of pile top against the frequency are shown in figures by means of the numerical method,and the effects of the saturated soil parameters,modu lusration of the pile to soil,slenderness ratio of pile and piles.Poisson ratio,etc.on the stiffness factor and damping are examined.It is shown that,due to the effect of the transversal deformation of the pile and the action of radial force of the saturated viscoelastic soil to the pile,the dynamic stiffness factor and the damping derived from the axisymmetrical solution are greatly distinct from those derived from the classical Euler-Bernoullirod model,especially at some specific excitation frequencies.Therefore,there are some limitations for the applicability of the Euler-Bernoulli rod model for analys is of the vertical vibration of the pile,and themore accurate analysis should be based on the three dim ensionalmodel.
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