对二滩水电站坝区场地地面运动的估计

本文以二滩地区为例,介绍如何结合地震危险性分析的结果,采用理论模拟方法估计工作地区近场强地面运动情况,为工程抗震设计提供必需的地面运动动力学参数。 文中采用理论方法计算剪切位错点源的格林函数;根据断裂动力学模型、近场地面峰值加速度衰减曲线和场地附近的加速度谱来标定震源模型;计算了若在坝区附近发生M_s=6.2级地震时场地的综合地震图、加速度傅氏谱和反应谱等。由理论模拟计算的峰值加速度衰减曲线和观测结果符合较好。在震中距为20km处的加速度谱的截止频率f_max与观测值相吻合（约为8 Hz左右）,相应的峰值加速度为211cm/s²,振动持续时间为3.4秒。

ESTIMATION OF STRONG GROUND MOTION FOR THE ERTAN DAM REGION

In this paper an actual example to estimate the near-field strong ground motion in the Ertan Dam is given by using the theoretical simulation method. This technique is useful for providing the dynamic ground motion parameters of the anti-seismic design.The synthetic seismograms and the response spectra are computed for an earthquake （M_s=6.2） which, according to the seismic hazard analysis, will be possible near the Ertan region. The Green's functions for a dislocation point source are computed with the theoretical method. The source rupture model is constructed by the dynamic rupture analysis, as well as the peak acceleration attenuation curve and the acceleration Fourier spectra near the site. The theortical peak acceleration and the cutoff frequency f_max （-8 Hz） are in good agreement with the observation results. According to this model the near-field ground motion parameters are given near the Dam.