SH波作用下桩-液化土-结构体系的水平振动特性

摘要

Treating a pile and a superstructure as a Timoshenko beam and a single degree of freedom springmass system,respectively,the horizontal vibration characteristics of the pile-liquefied soil-superstructure coupled system subjected to a vertical incident harmonic SH wave was investigated based on the Winkler model of the pile-soil interaction.The boundary value problem of the single pile-liquefied soil-superstructure coupled system was established,in which the free-field displacement of the soil,translational and rotational inertia of the superstructure and the second order effect of the axial pressure of the pile were taken into consideration.And the analytical solutions of the pile deformation and superstructure motion were derived.The influences of the geometry and physics parameters on the displacement amplification factors and dynamic amplification factors at the pile top and of superstructure were examined numerically.It is shown that there exists an evident resonance phenomenon in the single pile-liquefied soil-superstructure system,and the influence of the soil free-field displacement on the displacement amplification factors of the pile top and superstructure is remarkable.Furthermore,with the increase of the superstructure stiffness,fundamental frequency of the single pileliquefied soil-superstructure system increases and the peak value of displacement amplification factors decreases.At the same time,with the development of soil liquefaction degree,the fundamental frequency and dynamic amplification factors of the single pile-liquefied soil-superstructure system decreases.%将桩等效为Timoshenko梁,上部结构等效为单自由度弹簧质量块,基于桩-土相互作用的Winkler模型,研究了在垂直入射简谐SH波作用下桩-液化土-上部结构耦合体系的水平振动特性.考虑土体的自由场位移、上部结构的平动和转动惯性以及和桩轴向压力的二阶效应,建立了单桩-液化土-上部结构耦合体系的边值问题,得到桩变形和上部结构运动的解析解.数值分析了几何和物理等参数对桩头和上部结构位移放大因子和动力放大因子的影响,结果表明:单桩-液化土-上部结构体系存在明显的共振现象,且土体自由场位移对桩头和上部结构的位移放大因子影响显著;随着上部结构刚度的增加,桩-液化土-上部结构体系的基频增大,位移放大因子峰值减小;随着土体液化的发展,单桩-液化土-上部结构系统基频和动力放大因子逐渐减小.