地震动随场地深度变化的相干性分析

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振动与冲击 ›› 2019, Vol. 38 ›› Issue (9) : 140-147.

论文

地震动随场地深度变化的相干性分析

洪娜1,2，陈清军1,2

作者信息 +

Coherence analysis for ground motions with variation of site depth

HONG Na1,2,CHEN Qingjun1,2

Author information +

文章历史 +

摘要

目前有关地震动相干性研究基本上是限于自由场地的地面运动相干性问题。为探究地震动随场地深度变化的相干性，寻求一种适用于不同类型场地随深度变化的地震动相干函数模型，以日本KiK-net台网采集的2679对地震动记录为基础，利用随机振动理论和数字信号处理技术对不同类型场地随深度变化的地震动相干性问题进行了研究。通过对水平向地震动分量相干函数计算值的拟合，建立了一种适用于不同类型场地的水平向地震动随深度变化的相干函数模型，并进行了参数回归分析。分析结果表明：震级及震中距（<200km）对相干函数的影响可忽略不计；剪切波速对相干函数产生较大的影响，与浅层土相比，深层土剪切波速的影响更大；水平向地震动的相干函数值随深度和频率的增大呈指数形式衰减；相较于深度的影响，频率对相干函数值衰减速率的影响更加明显。在对地震动相干函数值的估计中，场地条件是不容忽视的因素，随着场地由硬变软，相干函数值随深度的衰减愈来愈快。

Abstract

At present, the research on the coherency of seismic ground motions is almost limited to the coherency problem of ground motion in free field. In order to investigate the variability of seismic ground motions on depth and seek a model to simulate coherency of ground motions function varied with depth for different types of sites, 2679 pairs of ground motion records were collected from KiK-net of Japan in this paper. The random vibration theory and the digital signal processing techniques were used to study the coherency varied with depth. By fitting the calculated coherency function of horizontal components of ground motions, a coherency model with unified mathematical expression for different sites was proposed and the corresponding parameters were analyzed. The results show that there is no significant dependence between the estimated coherencies from different earthquake magnitudes or epicentral distance (less than 200 km); shear wave velocity(VS) plays an significant role on depth coherency and compared with Vs of shallow soil, the effect of Vs of deep soil on depth coherency is notable; the coherence function varied with depth for horizontal components has an exponential reduction tendency along with increasing depth and frequency, and frequency plays a more significant effect on the velocity of coherency function than depth. Coherency function is site dependent: the softer the site condition, the faster decay the coherencies with depth.

导出引用

洪娜1,2，陈清军1,2. 地震动随场地深度变化的相干性分析[J]. 振动与冲击, 2019, 38(9): 140-147

HONG Na1,2,CHEN Qingjun1,2. Coherence analysis for ground motions with variation of site depth[J]. Journal of Vibration and Shock, 2019, 38(9): 140-147

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