三维台阶地形地震动效应研究  

Effect of 3-D step topography on ground motion

作　　者：丁志华[1] 周红[1] 蒋涵[1] 

机构地区：[1]中国地震局地球物理研究所,中国北京100081

出　　处：《地震学报》2014年第2期184-199,339,共16页Acta Seismologica Sinica

基　　金：国家自然科学基金重大研究计划项目(90915012)资助

摘　　要：运用谱元法模拟了不同类型三维台阶地形对点源地震动的影响,发现在中小地震中,大型山系边缘的三维台阶地形对地表地震波具有一定的影响.台阶斜坡与上水平地层交线和下水平地层交线的影响作用各不相同.通过地表接收到的地震动描述了各种不同地形的波形快照特点,并且通过绘制的台阶斜坡与上水平地层交线及下水平地层交线的测线图,发现波形相对于水平地形有明显的后续波.同时发现,台阶地形上下测线相对于水平地形具有放大作用.下测线波形放大倍数基本在1.1—1.5,上测线放大倍数在0.9—1之间.通过描述山体边缘台阶结构在点源地震中产生的影响,定量计算了三维台阶不同角度各个位置相对于水平地形的放大倍数,为以后工程研究提供一个依据.This paper simulates the different types of three-dimensional step to- pography effects on ground motion due to a point source by using spectral ele- ment method. Level topography and several different 3-D step topographies are simulated, which shows that the 3-D step topographies have an important im- pact on seismic waves. The effect from the intersecting lines of step slopes with upper level is different from that with the lower level. Moreover, the character- istics of various topographies are described using snapshots of the ground mo- tions; the measuring line diagrams of the intersecting lines of step slope with upper level and those with the lower level demonstrate that the waveform dia- grams of 3-D step topography have obvious scattering waves relative to level to- pography. Also it shows that the values on the upper and lower measuring lines on 3-D step topography are amplified relative to level topography. On the wave- forms of lower measuring lines the amplification ranges {rom 1.1 to 1.5, and that is from 0.9 to 1 on the waveforms of upper measuring lines. These studiesdescribe the impact of step topography at the edge of the mountain due to a point-source earthquake and give the respective positions~ magnification of the 3-D step topography relative to level topography, providing a basis for forward engineering studies.

关 键 词：谱元法 山体边缘地形 三维台阶地形 地形效应 点源 

分 类 号：P315.9[天文地球—地震学]