基于动力相互作用因子的饱和土中群管桩的纵向振动研究

利用动力Winkler弹簧-阻尼器,模拟桩周饱和土和桩芯饱和土与管桩的动力相互作用.在忽略饱和土径向位移和环向位移的情况下,将桩周饱和土视为由无穷多带一圆孔的薄土层组成,而桩芯饱和土视为由无穷多有界的圆形薄土层组成,运用数学物理手段求得了动力Winkler弹簧-阻尼器模型的刚度系数和阻尼系数.运用初始参数法和传递矩阵法,求得了饱和土中主动管桩和被动管桩的纵向位移,得到了饱和土中管桩-管桩纵向动力相互作用因子.基于管桩-管桩纵向动力相互作用因子和群桩叠加原理,得到了饱和土中群管桩的纵向动力阻抗.数值分析表明:桩间距越大,群管桩纵向动力阻抗随频率变化曲线波动越厉害;管桩内半径和管桩长径比越大,管桩纵向动力阻抗随频率变化曲线幅值越大,而桩土模量比越大则越小;桩间距对群管桩动刚度的影响最大,其次是管桩长径比,最小的是桩土模量比.

Study on Longitudinal Vibration of Pipe Pile Groups in Saturated Soil Based on Dynamic Interaction Factor

The dynamic interactions between the saturated soil around the pile and the pipe pile,and between the pile inner saturated soil and the pipe pile were modeled by the dynamic Winkler spring-damper. In the case of ignoring the radial and circumferential displacement of pipe pile,the saturated soil around the pile was supposed be composed by the infinite thin soil layers with a round hole,and the pile inner saturated soil was regarded as be composed by the infinite circular thin soil layers,and the stiffness coefficient and damping coefficient of the dynamic Winkler springdamper model were obtained by means of mathematics and physics. The vertical displacements of active pipe pile and passive pipe pile in the saturated soil were obtained by using the initial parameter method and the transfer matrix method,and the longitudinal dynamic interaction factor of pipe pile and pipe pile in the saturated soil was also got. Based on the principle of superposition of pile groups and the vertical dynamic interaction factor of pipe pile and pipe pile,the vertical dynamic impedance of pipe pile groups in the saturated soil was also obtained. The numerical analysis showed that: the curves of the longitudinal dynamic impedance of pipe pile groups will fluctuate more severe with the frequency when the pile spacing is bigger. The amplitude changes of the curves of the longitudinal dynamic impedance will be bigger with the frequency when the inner radius and the ratio of length to diameter are bigger,while the amplitudes will be smaller when the modulus ratio of the pipe pile and the saturated soil is bigger. The influence of pile spacing on the dynamic stiffness of pipe pile groups is the largest,followed by the ratio of length to diameter,and the modulus ratio of pipe pile and saturated soil is the smallest.