摘要
采用综合f-k滤波和基于S变换的极化分析方法,从盆地观测点的模拟时程中提取Rayleigh面波,研究盆地内外介质的阻抗比(IC)对盆地地表地震动及次生面波的影响。结果表明:①此方法能较好地识别和提取Rayleigh面波震相。②盆地放大效应受IR影响显著。水平分量最大放大系数(AFmax)随IC的增加而增大,最大约1.15;垂直分量AFmax随之降低,最大值0.85左右。同时,盆地斜边区域水平分量地震动的削减作用随IC减小而增强。③IC对盆地显著放大区域的分布特征影响明显。IC较小时,盆地内存在多个显著放大区域;IC较大时,此区域仅出现在盆地边缘。④随IC增加,两分量的面波幅值降低,面波持时变长,传播速度增大。⑤IC较小时,面波幅值在盆地内振荡明显,随IC增大,该值在盆地边缘处最大,向内部基本不变。⑥面波幅值与地震动峰值之比在水平分量上随IC增大而降低,最大比值出现在盆地边缘;在垂直分量上受IC影响不明显,主要随与盆地边缘距离的增加而增大。
A method for extracting Rayleigh wave phases from simulated seismograms is proposed by incorporating the F-K filtering and polarization analysis based on the time-frequency S transform.Then the effects of impedance ratio(IC)between basin sediment and surrounding rock on the basin ground motion and basin-induced surface wave are investigated.The results show that:(1)The Rayleigh waves can be satisfactorily identified and extracted by using this method.(2)The amplification effects of the basin are significantly affected by IC.The maximum amplification factor(AFmax)of the horizontal component increases with growing IC,with a largest value of about 1.15 for the studied cases.Contrastly,AFmax of the vertical component decreases with larger IC with the largest value of 0.85.In addition,horizontal ground motion at basin slope region is gradually weakened with reduced IC.(3)IC has obvious influences on the distribution features of intensely amplified regions of the basin.Under small IC,a few such regions occur in the basin,however,under large IC,these regions only appear at the basin edge.(4)With increasing IC,the amplitude of the basin-induced Rayleigh waves becomes lower,but the duration gets longer,and their travelling speeds become larger.(5)For the small IC case,an obvious oscillation of the surface wave amplitude(SWA)is observed,whereas for large IC model,the largest SWA only appears near the basin edge,and it is almost unchanged inside the basin.(6)The ratio of SWA to PGD decreases with the growing IC for the horizontal component,and the largest ratio occurs at the basin edge.However,this ratio is insensitive to IC for the vertical component,and it generally increases with larger distance from the basin edge.
作者
于彦彦
丁海平
刘启方
YU Yan-yan;DING Hai-ping;LIU Qi-fang(Key Laboratory of Structure Engineering of Jiangsu Province,Suzhou University of Science and Technology,Suzhou 215011,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2020年第4期667-677,共11页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金青年基金项目(51808371)
江苏省高等学校自然科学研究面上项目(18KJB560017)。
关键词
盆地
Rayleigh面波识别
阻抗比
地震动
放大效应
basin
identification of Rayleigh wave
impedance contrast
seismic ground motion
amplification effect
作者简介
于彦彦(1985-),男,博士,讲师,主要从事场地地震效应及波动数值模拟研究。E-mail:yyy_usts@126.com。
