地震波反演两种计算方法比较与频率截断问题的探讨
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摘要
基岩地震动的确定是场地地震反应与土-结构动力相互作用分析的关键步骤之一。本文首先对通过反演获取基岩地震波的波动法和有限元法做了简要比较,阐述了在深覆盖土层地震波反演分析中频率截断的重要性。然后,以上海某深覆盖土层场地为例,分别采用波动法和有限元法对不同深度土层(包括土层10 m深处、土层20 m深处、土层45 m深处、土层140m深处和土层280m深处)的加速度传递函数进行了计算分析与比较,结果表明,深覆盖土层的加速度传递函数的模在高频处趋近于零。在对传递函数深入分析的基础上,分别选用普通El Centro波和长周期TCU115波进行了反演分析,探讨了不同类型地震波在深覆盖土层反演中的频率截断问题,得到了有应用价值的结果。
It is a key step to determine the bedrock earthquake motion in the analysis of site seismic response and soil-structure dynamic interaction.Two methods of ground motion inversion of shear wave propagation and finite element were compared,and the question of frequency cut-off in ground motion inversion of soil layer with deep deposit was discussed.Then,two methods were applied to a representative site with deep deposit in Shanghai,the acceleration transfer functions from different subterranean levels (including layers below the surface 10m,20m,45m,140m and 280m) to the surface were calculated and compared.The results show that the transfer function modulus of deep soil-layer are close to zero in higher frequencies.Finally,the acceleration records from El Centro and TCU115 terminal station(for it is long period seismic wave) in CHI-CHI earthquake were chosen as the ground motions,and the question of frequency cut-off under El Centro wave and long period TCU115 wave was analyzed,and the bedrock waves below the surface 280 m was obtained.
It is a key step to determine the bedrock earthquake motion in the analysis of site seismic response and soil-structure dynamic interaction.Two methods of ground motion inversion of shear wave propagation and finite element were compared,and the question of frequency cut-off in ground motion inversion of soil layer with deep deposit was discussed.Then,two methods were applied to a representative site with deep deposit in Shanghai,the acceleration transfer functions from different subterranean levels (including layers below the surface 10m,20m,45m,140m and 280m) to the surface were calculated and compared.The results show that the transfer function modulus of deep soil-layer are close to zero in higher frequencies.Finally,the acceleration records from El Centro and TCU115 terminal station(for it is long period seismic wave) in CHI-CHI earthquake were chosen as the ground motions,and the question of frequency cut-off under El Centro wave and long period TCU115 wave was analyzed,and the bedrock waves below the surface 280 m was obtained.
引文
[1]谢君斐,石兆吉.地面运动的反演及其在震害分析中的应用[J].地震工程与工程振动,1981,(9):11-24.
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[3]蔡袁强,凌道盛,周迪永,钱磊.非线性分层地基地面运动反演分析[J].振动工程学报,2000,13(3),426-432.
[4]Schnabel P B,Lysmer J,Seed H B.SHAKE - A computer program for earthquake response analysis of horizontally layered sites,Report No EERC72-2[R].Earthquake Engineering Research Center,University of California,Berkeley,1972.
[5]张克绪,谢君斐.土动力学[M].北京:地震出版社,1989.
[6]胡聿贤,朱镜清,朱莉,胡勇.频域中的结构振动输入反演[J].地震工程与工程振动,1981,(1):41-47.
[7]黄雨,叶为民,唐益群,陈天聆.上海软土场地的地震反应特征分析[J].地下空间与工程学报,2005,1(5):773-778.
[2]陈厚群,侯顺载,王均.拱坝自由场地震输入和反应[J].地震工程与工程振动,1990,(6):53-64.
[3]蔡袁强,凌道盛,周迪永,钱磊.非线性分层地基地面运动反演分析[J].振动工程学报,2000,13(3),426-432.
[4]Schnabel P B,Lysmer J,Seed H B.SHAKE - A computer program for earthquake response analysis of horizontally layered sites,Report No EERC72-2[R].Earthquake Engineering Research Center,University of California,Berkeley,1972.
[5]张克绪,谢君斐.土动力学[M].北京:地震出版社,1989.
[6]胡聿贤,朱镜清,朱莉,胡勇.频域中的结构振动输入反演[J].地震工程与工程振动,1981,(1):41-47.
[7]黄雨,叶为民,唐益群,陈天聆.上海软土场地的地震反应特征分析[J].地下空间与工程学报,2005,1(5):773-778.
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