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Title:: Analysis of Influencing Factors of Ground Motion Coherence Function Along Depth Direction

Author(s):: ZHONG Jufang¹; CHEN Gong¹; 2; (1.Department of Civil Engineering,College of Civil Engineering and Architecture,Nanchang Hangkong University,Nanchang 330063,Jiangxi,China)(2.Department of Civil Engineering,Changde Vocational Technical College,Changde 415006,Hunan,China)

Keywords:: KiK-net strong motion records; ground motion; coherency function; influencing factors

摘要:: 基于KiK-net台网强震记录,探讨震级、震中距、场地类别及测点高差等对沿深度方向相干函数的影响规律。结果表明:①水平分量的相干函数值随频率变化规律相同,竖向与水平分量间的差异较大; 相干函数值随频率和测点高差的增加而减小; Ⅲ类场地较之Ⅰ,Ⅱ类场地,所记录的相干函数值随频率增加而衰减的速度更快。②近场(R≤300 km)相干函数值大于远场(R>300 km); 震级对相干函数的影响规律不明显; 不同场地记录沿深度方向地震动相干性不同,建议选用王招招模型描述Ⅲ类场地地震动相干性,Harichandran模型描述Ⅰ,Ⅱ类场地地震动相干性。③基于日本“3·11”地震记录拟合得到了按震中距分段的相干函数模型参数值。

Abstract:: Based on the data of several stations in KiK-net strong-motion seismograph network,we discussed the influence of magnitude,epicenter distance,site classification,and the height difference between the surface and the underground measuring points on the coherence function of ground motion along the depth.The results showed that:① The variation law of coherency functions in two horizontal components with the frequency was similar,but the difference of coherency functions between vertical and horizontal components was significant.The coherency function decreased with the increasing of frequency and height difference,and the attenuation speed of coherency function in vertical component in the class Ⅲ site was faster than that of both the classⅠand classⅡ site with the increasing of the frequency.② The coherence function value of near-field(R≤300 km)is greater than that of far-field(R>300 km).The influence of magnitude on coherency function was not significant.The coherences of ground motion were different in different site,and different coherence function models should be used in different site types.We suggested that the coherence of ground motion in class Ⅲ site can be reflected by the function model of Wang Zhaozhao,and that in classⅠand Ⅱ sites can be reflected by the Harichandran function model.③ Based on the data of Japan “3·11” earthquake,we fit the parameters of the coherence function model in epicenter distance range.