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为寻求一种适用于不同类型场地的地震动空间相干函数实用模型,从美国、日本和我国台湾的密集型强震观测台阵的35次地震记录库中,选取1116条地震动记录,利用随机振动理论和数字信号处理技术对不同类型场地的地震动空间相干性问题进行了研究。通过对水平分量地震动和竖向分量地震动空间相干函数计算值的拟合,建立了一种适用于软土场地、一般场地和基岩场地的地震动空间相干函数实用模型,并进行了参数回归分析。分析结果表明:地震动场空间任意两点的相干性随着距离和频率的增大呈指数函数形式逐渐减弱;在软土场地、一般场地和基岩场地三类场地中,软土场地衰减最快,一般场地次之,基岩场地衰减最慢;基岩场地在距离20km处仍有较大的相干函数值;地震动水平分量的相干性要大于竖向分量的相干性。
In order to find a practical model of spatial coherence function of ground motion suitable for different types of sites, 1116 ground motion records were selected from 35 seismological records of intensive strong earthquakes in the United States, Japan and Taiwan. By using random Vibration theory and digital signal processing techniques are used to study the spatial coherence of ground motion in different types of sites. By fitting the calculated values of spatial coherence function of horizontal and vertical component ground motions, a practical model of coherence function of ground motion, which is suitable for soft soil site, general site and bedrock site, is established and the parameters regression analysis. The results show that the coherence of any two points in the seismic field decreases gradually with the increase of the distance and frequency in the form of exponential function. Among the three kinds of sites in the soft ground, the common ground and the bedrock site, the attenuation of the soft ground In general, the attenuation of bedrock site is the slowest. Basement rock site still has larger coherence function value at a distance of 20km. The coherence of horizontal component of ground motion is greater than the coherence of vertical component.