强震动记录H/V谱比法计算处理的若干关键环节

Some Technical Notes on the Data Processing of the Spectral Ratio Based on the Strong-motion Records

强震动记录H/V谱比法自提出以来,已广泛应用于地震工程各研究领域中。但对数据处理的2个关键环节——Taper预处理及傅氏谱平滑未有详细研究。因此,本文针对强震动记录H/V谱比法计算涉及的重要数据处理过程,对四川地区19个强震动台站在汶川地震余震中获取的642组强震动记录开展研究。研究实例表明:S波H/V谱比振幅在周期<1s时高于全时程,论证计算H/V谱比时截取S波窗口的必要性;S波窗口的截断会引起傅里叶振幅谱的边瓣效应,若不加以处理,将显著影响低频部分H/V谱比结果,Taper预处理对于消除这种截断误差具有良好效果;在兼顾平滑效果及卓越周期识别准确度的基础上,通过不同带宽的Parzen窗试算,认为0.5Hz带宽宜用于傅里叶H/V谱比曲线平滑。

The H/V spectral ratio method based on strong motion record has been widely used in the field of earthquake engineering since it was developed;however,there are few research papers about the key steps of tapering the truncated S-wave time series and smoothing the Fourier amplitude spectrum in the strong-motion records.Based on 642 strong-motion records collected at 19 stations during Wenchuan aftershocks in Sichuan area,we illustrated some technical notes about data processing.The results show that the amplitude of the S-wave spectral ratio less than 1.0s period is higher than those calculated using the whole time series,and extracting S-wave window in calculating H/V spectral ratio is needed.The truncation of S-wave window could lead to the side lobe effect of Fourier amplitude spectrum,and the H/V spectral ratio at the low frequency part will be significantly contaminated if without tapering,which could effectively eliminate truncation error.On the basis of taking into account both the smoothing effect and the excellent accuracy of period identification,through the trial calculation of Parzen windows with different bandwidths,we consider that the 0.5Hz bandwidth is suitable for smoothing the Fourier H/V spectral ratio curve..