用数值模拟方法研究北京盆地对3~10 s地震动的放大效应*

(中国地震局地球物理研究所,北京 100081)

北京盆地; 盆地放大效应; 高层建筑; 地震致灾风险水平

Studying on Amplification Effect of Beijing Basin on 3~10 s Ground Motion by Numerical Simulation Method
FU Chang-hua,GAO Meng-tan,YU Yan-xiang

(Institute of Geophysics,CEA,Beijing 100081,China)

Beijing Basin; basin amplification effect; high-rise building; risk level of seismic hazard

备注

以北京盆地为例,针对不同的设定地震,研究了不同震源条件对盆地放大效应的影响。结果 表明:尽管震源因素可对计算结果带来一些不确定性,但盆地内沉积物的厚度是控制3~10 s周期段地震动加速度反应谱的主要因素。因此,计算了盆地对3~10 s周期段地震动加速度反应谱的平均放大系数,并通过回归分析得到了平均放大系数与盆地等效沉积物厚度之间的函数关系。最后,结合北京盆地内高层建筑的分布,初步探讨了高层建筑地震致灾风险水平与盆地结构的关系。

Taking Beijing Basin as an example,we set up several scenario earthquakes,and study the influence of the different epicenter condition on the basin amplification effect of ground motion.The research result demonstrates that although the different source factor may cause the uncertainty to the calculation result in a certain extent,the basin amplification effect on 3~10 s ground motion acceleration response spectrum is mainly controlled by the thickness of sediment in basin.Thus,the average basin amplification factor on 3~10 s ground motion acceleration response spectrum is computed,and the correlation function which is between the average amplification factor and equivalent thickness of sediment in basin is analyzed.Finally,according to the distribution of high-rise buildings in Beijing Basin,we preliminarily discuss the relationship between risk level of seismic hazard of high-rise buildings and basin structure.