地震动强度包络线对称性的研究

Studies on the Symmetry of Amplitude Envelope Line of Ground Motion

从欧洲强震记录数据库中挑选出163组强震记录,并按照震级、场地类别和震源机制进行分类,在此基础上讨论了地震动正负向包络线是否具有对称性,并分析了场地类别和震源机制对其的影响。结果表明,地震动正负向包络线一般都不具有对称性,正向包络线要比负向包络线饱满一些,其光滑程度也是不同的,正向包络线比负向包络线更光滑一些。场地类别对地震动正负向包络线的影响程度是比较复杂的,震源机制对地震动包络线不同持时段内的影响也是不同的,但平均包络线基本上都可以用单峰点的曲线来表示。

163 groups of strong ground motion records are picked up from Euro databank which are sorted according to earthquake magnitude and site classification. Based on these records, the symmetry of amplitude envelope lines of ground motion in positive and negative directions is discussed, and their effects on site classification and focus mechanism are investigated. From the statistical results, it can be seen that the envelope line is asymmetrical, and the envelope line in the positive direction is more plump than that in the negative direction. In addition, the degree of smoothness of the configuration of envelope line in the positive direction is different from that in the negative direction. In general, the envelope line in the positive direction is smoother than that in the negative direction. The effects on site classification of amplitude envelope line of ground motion in both positive and negative directions is rather complex, and the effect on focus mechanism of amplitude envelope line of ground motion in the positive direction differs from that in the negative direction. Moreover, the envelope lines in both positive and negative directions can be generally represented by single peak curves.