端承粘弹性桩纵向振动的轴对称解析解

AXISYMMETRICAL ANALYTICAL SOLUTION FOR VERTICAL VIBRATION OF END-BEARING VISCOELASTIC PILE

将桩和土体视为粘弹性介质,在频率域求得了桩轴对称纵向振动时动力响应的解析解,进而得到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,考察了土层粘性、桩长径比、桩土模量比、桩泊松比和粘性等参数对桩头刚度因子和等效阻尼的影响.研究表明:由于考虑了桩的径向变形效应以及土层对桩的径向力作用,轴对称解析解的桩头动刚度因子和等效阻尼与经典Euler杆模型桩的桩头动刚度因子和阻尼有较大区别.因此,经典Euler杆模型桩的适用范围具有一定的局限性,在若干情形下应采用基于三维粘弹性的桩纵向振动轴对称模型进行分析.

Regarding the pile and the soil layer as viscoelastic media,the axisymmetric analytical solution for the vertical vibration of the end-bearing pile is obtained in the frequency domain,and the analytical expression for the dynamical complex stiffness of the pile top is presented.Responses of dynamic stiffness factor and equivalent damping of the pile top to the frequency are shown in figures by means of the numerical method.The influences of the soil＇s viscosity,slenderness ratio of pile,modulus ratio of the pile to soil,pile＇s Poisson ratio and viscosity on the stiffness factor and equivalent damping are examined.It is revealed that,due to the effect of the transversal deformation of the pile and the radial force of the soil acting on the pile,the dynamic stiffness factor and equivalent damping derived from the axisymmetrical solution are greatly different from those derived from the classic Euler rod model.Therefore,there are some limitations for the applicability of the Euler rod model for analysis of the vertical vibration of the pile,and the axisymmetric model based on the three dimensional viscoelasticity should be employed under some special cases.