软泥夹层对香港软土场地地震反应的影响

Influence of soft sandwich layer on seismic response in Hong Kong

选择了香港有代表性的８个典型场地，通过钻探、现场剪切波速测量和土样动力实验建立了场地的分析模型，用２１次地震的１２８条基岩地震动记录作为输入，计算了场地土层地震反应。结果表明，对带海泥软夹层的砂质回填土场地，地震动的长周期分量（１．２～１．５ｓ）被显著放大了，现有抗震 规范的设计反应谱不能反映这类场地的反应特性。基于计算结果，提出了分别适合有、无软夹层场 地的归一化设计反应谱。

This paper presents the in-situ shear wave velocity measurements and laboratory dynamic tests of typical Hong Kong soil samples. Based on the test data and borehole information, we carried out seismic response analysis of eight typical soil sites in Hong Kong, using 128 bed-rock excitations of 21 earthquakes in China/overseas as input data. It was found that for reclaimed sites with a soft layer of marine deposits below a general (sandy)fill, substantial soil amplification effects would extend to a longer period(l.2-- l.5 second), and this has not been accounted for in seismic codes. Consequently, normalized design response spectra for soil sites with and without a sandwich-layer of soft soil were then proposed.