西南山区铁路沿线反倾岩质边坡地震动力响应振动台试验研究

Study of Shaking Table Test on Seismic Dynamic Response of Rock Counter⁃tilt Slope Along Southwest Mountainous Railway

以西南山区铁路沿线典型的含结构面反倾岩质边坡为例开展振动台试验,采用时频域分析方法研究输入不同峰值加速度地震波时该类边坡的地震动力响应特性。结果表明:随着高度的增加,加速度峰值放大系数总体上呈增大趋势仅局部有所减小,表明地震动力响应具有高程放大效应;在高度相等的情况下,除了底部坡内测点的加速度峰值放大系数大于坡体表面,其余同一高度的2个测点均是坡体表面的加速度峰值放大系数大于坡内,表明地震动力响应具有趋表放大效应;坡肩测点的加速度峰值放大系数比边坡2/3高度处明显增大,在峰值加速度为0.9g时加速度峰值放大系数达到最大值;坡内测点加速度傅里叶幅值谱的形态和分布与坡体表面测点基本一致,在20,30 Hz附近出现2个峰值,且随坡体高度增加,频谱分布逐渐变得复杂,加速度傅里叶幅值比逐渐增大,呈现出明显的高程放大效应。

Taking the typical rock counter-tilt slope with structural surface along the southwest mountain railway as an example,the shaking table tests were carried out.The seismic dynamic response characteristics of the slope with different peak acceleration seismic waves were studied by time frequency domain analysis.The results show that with the increase of height,the peak acceleration amplification coefficient increases in general,and is only partially reduced,which indicates that the seismic dynamic response has elevation amplification effect.In the case of the same height,the peak acceleration amplification coefficient at the measuring point in the bottom slope is greater than that of the slope surface,and for other two measuring points in the same height,peak acceleration amplification coefficient on the slope surface is greater than that in the slope,which shows that the seismic dynamic response has the effect of surface amplification.The peak acceleration amplification coefficient at the measuring point of slope shoulder is obviously larger than that at the 2/3 height of slope,and reaches the maximum value when the peak acceleration is 0.9g.The shape and distribution of the Fourier amplitude spectrum of the acceleration of the measuring points inside the slope are basically consistent with those of the measuring points on the slope surface.There are two peaks near 20 Hz and 30 Hz.With the increase of the height of the slope,the spectrum distribution becomes more and more complex.The Fourier amplitude ratio of the acceleration between the measuring points on the slope surface or inside the slope and the measuring points on the platform gradually increases,showing an obvious elevation amplification effect.