汶川地震紫坪铺面板堆石坝地震波输入研究

对国家强震动台网中心紫坪铺面板堆石坝区域台站实测主震记录以及大坝台网实测余震记录进行分析，研究主震与强余震地震动的基本特征。分别选取茂县地办、郫县走石山、成都中和这3组基岩台站实测主震地震动，紫坪铺台站2008年11月6日实测余震地震动以及按水工抗震规范人工生成地震动作为数值计算的地震动输入，对紫坪铺大坝进行三维动力有限元分析，并与实测结果进行对比。研究表明，郫县走石山与成都中和2个远场台站位于断层下盘，其实测地震动的加速度反应谱长周期（0.65 s以后）分量过于丰富，不宜作为断裂带附近紫坪铺大坝的地震动输入；紫坪铺大坝台站实测的余震地震动1 Hz附近（大坝基频）的频率成分相对较少，且持续时间较短，以至于难以激发大坝响应；对比坝顶实测地震动加速度反应谱和数值计算反应谱，建议汶川地震中紫坪铺大坝动力计算时可采用茂县地办台站实测地震动或按抗震设计规范反应谱人工生成地震动。

Study of seismic wave input of Zipingpu concrete face rockfill dam during Wenchuan earthquake

The main shock measured by stations of China strong motion networks center(CSMNC) around Zipingpu concrete face rockfill dam(CFRD) and the aftershock measured by Zipingpu stations are analyzed.The basic characteristics of strong ground motions are studied.Three-dimensional dynamic finite element analysis is adopted to analyze Zipingpu CFRD while the main shock measured by stations like Diban of Mao county(DBM),Zoushishan of Pi county(ZSP),Zhonghe of Chengdu(ZHC) and recorded aftershock of rock stations on dam site on Nov.6,2008 and artificial ground motion generated by standardized spectrum of specifications for seismic design of hydraulic structures as seismic input;and then comparison between the finite element data and the measured data is made.It is shown that the long period component(0.65 s later) of response spectrum of ground motion recorded by stations of ZSP and ZHC is much too rich as these far-field stations locate in the footwall of fault.As Zipingpu dam locates near the fault,main shock recorded by far-field stations can not be used as seismic input.The components in the range of about 1 Hz(base frequency of the dam) of the aftershock recorded by stations of Zipingpu dam are lower and the duration is less so that it is difficult to stimulate the dam.Compared with measured and calculated spectra on dam crest,ground motions measured by Diban station of Mao county and artificial ground motion generated by standardized spectrum are suggested to be used in dynamic analysis of Zipingpu dam during Wenchuan earthquake.