北京地区中硬场地地震动效应研究

A Study on Seismic Effect of Medium-Stiff Soil Site in Beijing Area

依据典型工程场地的地震安全性评价报告,研究北京地区中硬场地地震动效应。首先,统计分析了地震安全性评价结果中的场地地震动放大效应。再利用201个工程场地的钻孔资料进行土层地震反应计算,分析不同地震动输入下的场地地震动放大效应。结果表明,北京地区中硬场地地震动放大效应明显,得到的场地地震动峰值加速度转换系数Ka高于《中国地震动参数区划图》(GB18306-2001)中的值,大震水准下更为突出。因此,如在北京地区直接采用《中国地震动参数区划图》(GB18306-2001)中的调整系数,可能会低估北京地区中硬场地的地震动放大效应,降低抗震设防标准。最后指出,场地地震动峰值加速度转换系数明显具有区域性,应根据详细的场地地震动效应研究结果,合理地确定场地地震动转换系数。

In this paper the reports of seismic safety evaluation of the typical sites are used to study the seismic effect of medium-stiff soil site in Beijing area.Firstly,the seismic amplification effect is statistically analyzed from the reports of seismic safety evaluation.Secondly,based on the bore data of 201 typical engineering sites,the seismic response analysis of soil layer is carried out,and the seismic amplification effects for various seismic inputs are analyzed.Our results indicate that the seismic amplification effect of medium-stiff soil site is remarkable in the study area,the seismic peak ground accderation factor Ka of the site is larger than that recommended in GB18306-2001 ＂Seismic Ground Motion Parameter Zonation Map of China＂,especially for large earthquake.Therefore,if the adjustment factor in GB18306-2001 ＂Seismic Ground Motion Parameter Zonation Map of China＂ is used directly,the seismic amplification effect of medium-stiff soil site may be underestimated,and the seismic fortification criterion may be played down in Beijing area.Finally,we point out that the seismic peak ground accderation factors Ka of the site clearly has territorial,and the seismic factor must be determined reasonably on the basis of the detailed research results of the seismic effect of the site.