不同压实度铁路路堤边坡地震响应振动台试验研究

Shaking table test on seismic response of railway embankment slopes with different compaction degrees

为研究和对比不同压实度铁路路堤边坡的地震响应,设计了路堤本体压实度分别为95%、91%、87%和83%的4组路堤边坡模型,开展了不同压实度路堤边坡的振动台试验研究。通过穿插进行白噪声激励得到不同压实度路堤边坡的动力特性参数;通过施加不同类型和不同强度的地震动激励,研究不同压实度路堤边坡加速度放大倍数分布规律及其影响因素。结果表明,随着地震动激励次数的增多,路堤边坡自振频率下降,阻尼比增大,压实度对路堤边坡动力特性变化影响显著;加速度放大倍数沿路堤边坡高度呈非线性增大,加速度放大倍数随地震动激励强度增大而减小;台面输入的地震波经路堤边坡传播后,其频谱特性发生了明显的变化,不同压实度路堤边坡对地震波频谱特性的影响不同;不同地震动激励下不同压实度路堤边坡的加速度放大倍数分布情况有所差异,这与地震动频谱特性和路堤边坡动力特性参数有关。

In order to study and compare the seismic response of railway embankment slopes of different compaction degrees,shaking table model tests on railway embankment slopes with compaction degrees of 95%,91%,87% and 83% in embankment noumenon are designed and carried out.White noise excitations are interspersed among seismic waves to obtain dynamic characteristic parameters of embankment slopes with different compaction degrees.Different amplitudes and different types of seismic waves are performed to study the distribution behaviors of acceleration magnification along the height of embankment slopes and their influential factors.The results show that the natural vibration frequencies of embankment slopes decrease,and damping ratios increase with the increase of seismic excitations.The dynamic characteristics of embankment slopes are greatly affected by the compaction degree of embankment noumenon.Acceleration amplifications increase nonlinearly along the height of embankment slopes;and the acceleration amplifications decrease with the increase of input excitation intensity.The embankment slopes make the spectrum characteristics of input seismic waves change greatly;and the spectrum characteristics of acceleration responses differ among the embankment slopes of different compaction degrees.The distributions of acceleration magnification of different compaction degree embankment slopes differ under excitations of different seismic waves,which are influenced by both of the spectrum characteristics of seismic waves and dynamic characteristics of embankment slopes.