自由振动时带承台单桩的纵向动力特性

基于广义Voigt模型,在考虑桩身材料阻尼情况下,研究带承台单桩的竖向自由振动问题.根据阻抗传递法推出桩顶阻抗,将所求得的桩顶阻抗作为支承刚度代入承台的自由振动微分方程中,运用Laplace变换及逆变换推导得到承台自由振动位移在时域范围内的半解析解.采用参数研究方法,分析桩径、桩长、桩身材料阻尼以及不同性质的桩侧土层对带明置承台单桩自由振动特性的影响；将所得解与工程实测曲线进行对比,结果表明：得到的理论计算结果与工程实测数据较接近,理论方法能够反映工程实际.

Vertical dynamic characteristics of single pile with cushion cap undergoing free vibration

Based on generalized Voigt model, the vertical free vibration of single pile with cushion cap was theoretically investigated by considering the viscosity of pile material. First, pile top the impedance is calculated according to the impedance transformation principle. Then, substituting the top impedance which serves as the supporting rigidity into the dynamic equilibrium equation of free vibration cushion cap, a semi-analytical solution for time-domain displacement curve can be obtained by using Laplace transformation and inverse transformation methods. Parametric study method was adopted to study the effects of pile diameter, length, material viscosity and different soil types on the free vibration characteristic of pile with exposed cushion cap. Finally, a comparison between the theoretical curve and the measurement values is conducted. The results of the present approach and the engineering practice show good agreement．