芦山强震记录中的奇异波形研究
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摘要
本文选取芦山地震中的强震记录,在对其进行地震事件的校核、转换数据格式、零线校正,形成标准格式的未校正加速度数据并绘制波形图后,研究发现加速度记录中存在具有规律的噪声、尖刺、断尾、明显的基线平移现象,并初步分析了其产生的原因,给出了合理的处理方法,研究了校正前后对于傅里叶幅值谱和反应谱的影响。研究表明:(1)滤波的方法可以降低甚至消除强震记录中有规律的噪声;(2)通过滤波和三分量加速度PGA所在时刻的一致性可以确定记录中的"尖刺";(3)连续重复数据点的搜索方法可用于分离加速度记录数据包的拼接;(4)通过加速度记录各时间点数据的累加可以确定时程中出现明显基线平移的时刻;(5)奇异波形的出现直接影响到时程、频谱及反应谱的特性。
In this article,strong motion records of the "4. 20"Lushan earthquake are selected and processed by seismic events correction,transformation and unification of data-format,zero-line correction and uncorrected acceleration time histories plotting in uniform-format routinely. Regular noise,"spike",the initial or end part missing and obvious baseline drift are found in strong motion records from Lushan earthquake. Then reasons and processing methods are proposed,at the same time,the effect on fourier spectrum and response spectrum is offered. Results show that:( 1) regular noise can be reduced or even got rid by filtering;( 2) compared with the agreement of PGA time for three directions,the "spike"in strong motion records can be identified by filtering;( 3) two pieces of strong motion record data pocket can be connected by finding continuous and repeated data;( 4) we can find the time for the starting of baseline drift by cumulative adding;( 5) time history,fourier spectrum and response spectrum are affected by wizard wave in strong motion records.
In this article,strong motion records of the "4. 20"Lushan earthquake are selected and processed by seismic events correction,transformation and unification of data-format,zero-line correction and uncorrected acceleration time histories plotting in uniform-format routinely. Regular noise,"spike",the initial or end part missing and obvious baseline drift are found in strong motion records from Lushan earthquake. Then reasons and processing methods are proposed,at the same time,the effect on fourier spectrum and response spectrum is offered. Results show that:( 1) regular noise can be reduced or even got rid by filtering;( 2) compared with the agreement of PGA time for three directions,the "spike"in strong motion records can be identified by filtering;( 3) two pieces of strong motion record data pocket can be connected by finding continuous and repeated data;( 4) we can find the time for the starting of baseline drift by cumulative adding;( 5) time history,fourier spectrum and response spectrum are affected by wizard wave in strong motion records.
引文
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[4]Boore,D.,J.Bommer.Processing of strong-motion accelerograms:needs,options and consequences[J].Soil Dynamics and Earthquake Engineering,2005,25:93-115.
[5]J.Bommer,Boore,D.Guidelines and recommendations for strong-motion record processing and commentary[R].Strong-Motion Record Processing Working Group,2005.
[2]Shin Aoi,Takashi Kunugi,Hiroyuki Fujiwara.Trampoline Effect in Extreme Ground Motion[J].Science,2008,322(5902):727-730.
[3]周正华,温瑞智,卢大伟,王玉石,李小军,于桦,龙承厚.汶川地震中强震动台基墩引起的记录异常分析[J].应用基础与工程科学学报,2010,18(2):304-312.ZHOU Zhenghua,WEN Ruizhi,LU Dawei,WANG Yushi,LI Xiaojun,YU Hua,LONG Chenghou.Analysis on Anomaly of Accelerograms in the Wenchuan Earthquake Caused by the Instrument Pier[J].Journal of basic science and engineering,2010,18(2):304-312.
[4]Boore,D.,J.Bommer.Processing of strong-motion accelerograms:needs,options and consequences[J].Soil Dynamics and Earthquake Engineering,2005,25:93-115.
[5]J.Bommer,Boore,D.Guidelines and recommendations for strong-motion record processing and commentary[R].Strong-Motion Record Processing Working Group,2005.
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