地震动持续时间的影响要素与影响规律探究

Research on the influencing elements and influencing laws of the duration of earthquake ground motion

为了研究震级、断层距以及土层平均剪切波速对地震动持续时间(有效持续时间、70%和90%能量持时)的影响,利用PEER地震动数据库强震记录,按照震级、断层距以及土层平均剪切波速与中国场地类别划分标准的对应关系对所选地震记录重新分组,通过研究地震动3个方向持时与上述因素之间的关系,进一步对比分析持时及其受各因素影响程度的差异。结果表明:持时随震级和断层距增大而延长,随土层平均剪切波速增大而减小;同时震级、断层距以及土层平均剪切波速对3个方向持时均存在明显影响,总体来说,2个水平方向持时相差相对较小,虽然竖直向和水平向持时随各影响因素变化曲线相似,但是二者仍存在明显差异。

In order to study the influence of earthquake magnitude, fault distance and average shear wave velocity of the soil within 30 m below the surface on the effective duration, 70% and 90% energy duration of earthquake ground motion, the earthquake records from PEER Earthquake Ground Motion Database are regrouped by magnitude, fault distance and the corresponding relationship between the average shear wave velocity of the soil layer and the Chinese site classification standard. In each group, the relationship between the durations in three directions and various factors and the difference of duration in three directions are studied. The results show that the durations increase as the magnitude and fault distance increase, and decrease as the average shear wave velocity of the soil increases;at the same time, the magnitude, fault distance and average shear wave velocity of the soil have obvious effects on the durations in three directions. In general, the difference of horizontal durations is relatively small, and the vertical and horizontal durations have similar curves with various factors, while the vertical duration and horizontal durations are quite different.