【摘要】 通过汶川地震震后科学考察发现,汶川地震局部场地的震害和地震动放大效应明显,地震对甘肃省境内远离震中的黄土地区造成了较为严重的破坏。在此基础上,结合钻孔波速测试,运用二维等价线性时程响应动分析法对甘肃省平凉市典型黄土塬进行了地震动力响应计算,分析了该地区局部场地条件对地震动放大效应的影响。研究发现,黄土塬具有地震动放大效应,随着塬高的增加,加速度、速度、位移均出现放大效应;随着地震动在黄土覆盖层中的传递,卓越频率向低频移动,高频成分被吸收,加速度反应谱中长周期分量逐渐增大。数值计算结果与实际震害基本吻合,其结果对黄土地区进行合理的抗震设防具有一定的科学意义。更多还原

【Abstract】 Based on earthquake damage investigation after the Wenchuan Ms8.0 earthquake,it is discovered that the phenomena of site amplification effects on ground motion were very obvious both in the mountainous area of southeastern Gansu province and the Loess Plateau areas.Combining with the borehole exploration,site seismic response analysis of the typical loess tableland at Pingliang City,Gansu province is carried out applying the dynamic finite element method of two dimensions linearly equivalent for dynamic response numerical calculation;the local amplification effect of the loess tableland is studied as well.The results show that there are seismic amplification effects at loess tableland;and acceleration,velocity and displacement increases with increase in tableland height gradually.Moreover,the low frequency components become more abundant and the high-frequency components are absorbed with increase in tableland height.The long-period components of acceleration response spectrum have increased gradually as well.The numerical results are basically consistent with the earthquake damages,so as to have certain scientific significance for the reasonable seismic fortification in loess regions.更多还原