【摘要】 软弱场地的地震动效应问题一直是工程地震学的研究重点。本文所说的软弱场地主要对应场地分类中的Ⅳ类场地,覆盖层较厚并含有软弱土夹层,以天津滨海地区为主要代表。研究表明,场地土本身对地震动具有放大作用,而软夹层具有减震作用,含软夹层的软弱场地对地震动参数的影响可以认为是场地土和软夹层对地震动参数的影响共同叠加的结果。叠加的结果将使其具有不同于其他场地的特点。本文选取了天津滨海地区不同地点的钻孔实例来进行计算,说明这类场地对地震动参数的影响。从计算的结果看,对地表峰值加速度而言,含软夹层的软弱场地的放大系数要小于其他类别场地的放大系数,而且在输入地震动较小时相对于地震动输入是放大作用;在输入地震动峰值较大时,表现为减震作用。对反应谱的特征周期而言,场地越软,反应谱越宽,特征周期值越大,而且随着输入峰值加速度的增加,特征周期也增加。对反应谱平台值来说,场地的影响并不显著。更多还原

【Abstract】 The ground motion effects of soft site have been the focus of research on engineering seismology.The soft site in this article refers to class IV venues of the site category,with very thick covering and containing soft interlayer.The Tianjin Coastal area is representative of this kind of site.Studies have shown that site soil has an amplifying effect on ground motion,while the soft interlayer has a damping effect.The impact of soft site with soft interlayer on the ground motion parameters is considered the superposition of the effects of soft site soil and soft interlayer.The result of superposition is that they have different features from other sites.This article chooses drilling examples from Tianjin coastal area to illustrate the ground motion parameters of this kind of site.From the result of the calculation,for the peak acceleration,the amplification factor of soft site is less than other types of site,and when the input ground motion is small,the effect of site is amplifying; but when the input ground motion is large,the soft site can cause a damping effect.As for the characteristic periods of response spectra,the softer is the site,the wider is the response spectrum,the larger the value of characteristic period,and with the input peak acceleration increasing,the characteristic period is also increased.Moreover,with the increase of the input peak acceleration,the characteristic period is also increased.For the response spectrum platform value,the influence of the site is not significant.更多还原