地震反应分析中输入界面的选取对地表地震动参数的影响

Influence of Input Interface Selection on Ground Motion Parameters in Seismic Response Analyses

摘要:

地震反应分析中输入界面选取合理与否对设计地震动参数有重要影响。基于唐山地区钻孔剖面，分别选取剪切波速为500 m/s的硬黏土和800 m/s的岩石顶面作为基岩输入界面，采用一维等效线性化方法讨论中硬场地输入界面的选取对地表地震动参数的影响，结果表明：（1）地表峰值加速度放大倍数及地表加速度反应谱特征周期都随输入界面深度的增加而递增，且这种递增与输入地震动的强度及频谱特性都有密切联系；（2）随着输入界面深度的增加，地表加速度反应谱几乎全频段内增大，仅在短周期内出现减小的情况，但幅度十分有限；（3）中硬场地地震反应分析中基岩输入界面宜取剪切波速为800 m/s的土层顶面。

Abstract:

The input interface selection has a significant influence on the ground motion parameters in seismic response analyses. Based on borehole profiles in Tangshan area, the top surfaces of rocks with shear-wave velocities of 500 m/s and 800 m/s are chosen as the input interface. Then the effect of input interface in medium-stiff soil site on ground motion parameters are discussed using the 1D equivalent linear method. The results show that (1) the peak ground acceleration magnification and the characteristic period of the surface acceleration response spectrum both increase with the depth of input interface, and the increment is closely related to the intensity and spectral characteristics of the input ground motion; (2) with the increase in the input interface depth, the surface acceleration response spectra almost increase in full frequency range and decrease only in some short period with a limited amplitude; (3) it is appropriate to choose the interface of soil with 800 m/s shear velocity as the input interface in seismic response analyses.