前后排抗滑桩加固滑坡桥基的振动台试验研究

 设计并完成前后排抗滑桩加固滑坡桥基的振动台模型试验。通过输入不同频率、加速度峰值的正弦波，分析振动时桥墩基桩、抗滑桩的受力变形规律，以及PGA放大系数变化特性。试验结果显示，当滑体为可塑的粉质黏土时，后排抗滑桩桩后土压力峰值分布随台面加速度峰值变化，由三角形逐渐变为倒三角形；由于桥墩、后排抗滑桩间距很小，两者相互作用增强，桥墩基桩受到较大的动力荷载影响，随着台面振动加速度峰值增加，桥墩基桩的应变最大值从桩顶下移至滑面附近；当正弦波加速度峰值相等时，频率越高，土体黏滞阻尼越小，滑坡的PGA放大系数越大，相应云图呈层状分布，同时高频振动波使土体产生较小的位移和变形，导致滑坡推力也较小；振动波在向上传播时，土体存在滤波效应，自振频率附近的频谱幅值会被放大。

Shaking table test on slope foundation of bridge reinforced with two rows of anti-slide piles

This paper presents a shaking table test on slope foundation of bridge reinforced by two rows of anti-slide piles. The dynamic loading applied is the sine waves with different frequencies and peak accelerations. The mechanical responses of the bridge foundation and anti-slide piles and the variation of amplification coefficient of PGA are analyzed. The results show that the distribution of peak soil pressure behind the back row anti-slide piles changes with the peak acceleration of shaking table in plastic silty clay. Due to the small distance between the bridge pier and back row anti-slide piles，the dynamic load affects the bridge foundation greatly，and the maximum strain of bridge pile foundation moves from the pile top to the sliding surface in the loading process. When the peak accelerations of sine waves are the same，the higher frequency of vibration means the smaller of viscous damping and the larger of PGA amplification coefficient in soil. The PGA amplification coefficient of the slope is distributed in layers. Meanwhile，the vibration waves of high frequency cause the smaller displacement and deformation in soil and lead to a smaller landslide thrust. When the vibration waves propagate up in soil，the spectrum of amplitude is magnified near the natural vibration frequency due to the filtering effect.