不同荷载速度下弹性土体中排桩的隔振效果分析

Vibration isolation for moving loads with different velocities by using piles-in-row embedded in an elastic medium

利用Muki和Sternberg的虚拟桩法,分析了不同荷载速度下弹性土体地基中排桩对移动荷载引起振动的被动隔振效果。首先由积分变换推导弹性土体表面受移动荷载的自由波场解、内部受圆形均布简谐荷载作用下的基本解,再根据基本解与桩土变形协调条件,建立了频域内土—桩的第二类Fredholm积分方程。最后通过求解积分方程与相应的积分逆变换得到时间域内评价隔振效果的振幅比。通过与已知文献结果比较,验证本文方法的正确性。数值结果表明:荷载速度对排桩的隔振效果有一定影响:当移动荷载小于土体的剪切波速时,随荷载速度增加排桩的隔振效果会降低,然而当荷载速度大于土体的剪切波速后,部分区域的隔振效果较好。

Based on the Muki and Sternberg's method,the vertical vibration isolation due to moving loads with different velocities using pile-in-row embedded in an elastic half space is investigated.Using the transform method,the free field solution for a moving load applied on the surface of the elastic half space is obtained,and the fundamental solution for a harmonic circular patch load applied in the elastic half space is derived.Using the free field solution as well as the fundamental solution,the second kind of Fredholm integral equation in the frequency domain describing the dynamic interaction between piles-in-row and the elastic half space is developed.After numerical solution of the frequency domain integral equation and inversion of the corresponding integral transform,the amplitude reduction ratio used to assess the vibration isolation effect of piles-in-row is obtained.Comparison of our results with the existing results shows that our results are in good agreement with the existing ones.Numerical results of this study show that the speed of moving loads has an important impact on the vibration isolation effect of piles-in-row.With the increasing moving load speed,the vibration isolation effectiveness decreases when the speed of the moving load is lower than the shear speed of the elastic half space,while a better vibration isolation effect for high speed loads can be obtained in part of the elastic half space.