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为了详细研究均质及复杂非均质场地中地震动的放大效应,通过大型振动台试验获得原始试验数据,再采用傅立叶变换、时频分析与分段时频分析相结合的手段,对试验数据进行分析和处理。通过对试验结果的对比分析,发现当地震动沿竖直方向传播时,不仅地震动时程曲线的峰值会随场地高度的增加而逐步放大,其频率成分含量、主频段的频谱形状,以及整体地震动能量在时频平面上的分布,均会随着场地高度及各分层介质的不同而发生较大变化。与此同时,场地表面的倾斜程度、软弱夹层的厚度等因素也均对地震动的放大效应具有显著影响。通过以上研究,得到了一系列与地震动竖向传播放大效应相关的研究规律(包括PGA峰值特性、频谱特性、时频面上能量谱的分布特性等)。
In order to study the amplifying effect of ground motions in homogeneous and complex inhomogeneous fields in detail, the original test data were obtained through a large-scale shaking table test, and then the combination of Fourier transform, time-frequency analysis and fractional time-frequency analysis was used to analyze the experimental data Analysis and processing. Through the comparative analysis of the test results, it is found that when the local vibration propagates in the vertical direction, not only the peak value of the ground motion curve will be gradually enlarged with the increase of the height of the field, the frequency content, the spectral shape of the main frequency band, The distribution of kinetic energy in the time-frequency plane will change greatly with the height of the site and the different layers of media. At the same time, the inclination of the surface of the site and the thickness of the weak interlayer also have a significant impact on the amplification effect of ground motions. Through the above research, a series of research rules (including the PGA peak characteristics, spectral characteristics, distribution characteristics of energy spectrum on the time-frequency plane, etc.) related to amplification of vertical seismic motion are obtained.