强震加速度记录的数据处理方法

本文用数值积分法,对RDZ1-12-66型自动触发电流计记录式强震仪的幅频响应失真进行校正。并采用高通数字滤波的方法,修正加速度图的零线.为此编制了计算机程序,绘制了修正后的加速度、速度和位移时程曲线.计算了修正前后加速度图的傅氏谱。同时,对这些结果加以讨论。 修正后的加速度图,精确地表示了仪器基本频带在0.09HZ和25HZ之间的绝对地面加速度。      

Interactive Correction of the Long-Period Trend in the Deconvolution Algorithm of Seismic Records

Ground displacement reconstruction is an ill-posed problem. Therefore, additional assumptions that ensure the stability of the resulting solution have been used to solve it. Interactive correction of the trend in the time domain, which makes it possible to remove a group of long-period trends from the seismic record without repeating the procedure, can be used as an alternative to the regularization of the solution in the deconvolution algorithm. Interactive trend correction is used within the proposed criterion. In the paper, the algorithm for calculating accelerograms from velocigrams with an integrated procedure for the interactive correction of the long-period trend has been given. The efficiency of the algorithm, which is based on the relationship of the differential equation of motion of the velocimeter pendulum to the true acceleration of the foundation bed, has been shown experimentally.     

A note on the noise amplitudes in some strong motion accelerographs

The amplitudes of digitization and processing noise in strong motion digital and analog accelerographs are discussed and compared with those for hand and automatic digitization. By finding the period bands for which the signal-to-noise ratio in recorded accelerograms is greater than one, the values for the pass-band cutoff periods for data processing are presented. The Empirical scalings for amplitudes in terms of: (1) earthquake magnitude and epicentral distance and, (2) Modified Mercalli Intensity at the recording site have been employed.     

强震加速度记录的常规处理和分析方法

本文针对我国强震台网所普遍使用的电流计记录式强震仪和模拟记录数字化设备的特点,系统、全面地分析了数字强震加速度记录中包含的各类误差的性质和特点,在这样基础上给出的调整(未校正)加速度记录、校正加速度记录以及各类反应谱和傅氏谱的结果具有统一的精度和标准的格式.从而可以在相当广泛的范围内满足地震工程研究对常用地震动数据处理和分析的需要.      

基于强震记录估算同震位移的研究进展及方法

通过对强震加速度记录估算同震位移技术自20世纪40年代以来国内外研究成果的总结,系统地阐述了通过近断层加速度记录计算同震位移的相关理论、方法的发展历程和成就。首先简述了基于强震记录估算同震位移的意义和普遍存在的漂移现象,然后总结了从模拟记录到数字记录两个阶段计算同震位移所取得的成果,接着归纳了为解决漂移现象所采取的3种基于时程拟合的方法和2种基于小波分析的方法,最后对基于数字强震仪记录估算同震位移的未来研究进行了展望。     

Correction of highly noisy strong motion records using a modified wavelet de-noising method

During the past earthquakes, many valuable acceleration time histories were recorded by analog and digital accelerometers. These records are important sources of information in the field of earthquake engineering and engineering seismology. However, a large number of these records are contaminated by noise and it is necessary to correct them for practical applications. On the other hand, only a few records can be corrected using conventional filtering because of mathematical limitations of the method. However, advances in the field of time–frequency analysis and wavelet transform theory provide useful non-linear and adaptive de-noising methods for removing of non-stationary and high-energy noise from the recorded signals. In this paper, the characteristics and capabilities of the modified non-linear adaptive wavelet de-noising method are examined for correction of highly noisy strong motion records. In the frequency domain, it is shown that this method can attenuate the noise in the whole frequency range of engineering interest while in the time domain it can detect and remove non-stationary noise. In addition, the displacement response spectra of these wavelet de-noised records are more stable than conventional filtered records with respect to different correction functions. It is found that a large number of noisy acceleration records that are usually discarded from sets of records used for estimating the ground motions can be corrected using this new method.     

Synthesis of accelerograms compatible with the Chinese GB 50011-2001 design spectrum via harmonic wavelets： artificial and historic records

A versatile approach is employed to generate artificial accelerograms which satisfy the compatibility criteria prescribed by the Chinese aseismic code provisions GB 50011-2001. In particular, a frequency dependent peak factor derived by means of appropriate Monte Carlo analyses is introduced to relate the GB 50011 -2001 design spectrum to a parametrically defined evolutionary power spectrum (EPS). Special attention is given to the definition of the frequency content of the EPS in order to accommodate the mathematical form of the aforementioned design spectrum. Further, a one-to-one relationship is established between the parameter controlling the time-varying intensity of the EPS and the effective strong ground motion duration. Subsequently, an efficient auto-regressive moving-average (ARMA) filtering technique is utilized to generate ensembles of non-stationary artificial accelerograms whose average response spectrum is in a close agreement with the considered design spectrum. Furthermore, a harmonic wavelet based iterative scheme is adopted to modify these artificial signals so that a close matching of the signals' response spectra with the GB 50011-2001 design spectrum is achieved on an individual basis. This is also done for field recorded accelerograms pertaining to the May, 2008 Wenchuan seismic event. In the process, zero-phase high-pass filtering is performed to accomplish proper baseline correction of the acquired spectrum compatible artificial and field accelerograms. Numerical results are given in a tabulated format to expedite their use in practice.     

力平衡式加速度计仪器响应误差的校正方法

本文通过对数字强震仪系统使用的力平衡加速度计的仪器响应误差进行分析,提出了一个校正仪器响应失真的处理方法(微分-微分方法),即对未校正记录做低通滤波后运用近似理想微分器做两次微分得到校正加速度记录。针对大亚湾核电站地震仪表系统(K IS)给出了仪器校正示例,并编制了相应计算软件。该方法适用于我国强震动台网数字强震仪获取的加速度记录的仪器响应误差校正处理。     

Near-source ground motion attenuation relationship for PGA and PSA of the vertical and horizontal components

In this paper, empirical ground-motion models for the vertical and average horizontal components of peak ground-motion and acceleration response spectra from shallow crustal earthquakes are derived using near-source database. These attenuation relationships were derived using a worldwide dataset consisted of corrected and processed accelerograms of 678 strong-motion records recorded with 60 km of the rupture plane of earthquakes between M_w 5.2 and 7.9. Ground motion models are functions of earthquake mechanism, distance from source to site, local average shear wave velocity, nonlinear soil response, sediment depth, depth-to-top of the rupture, hanging wall effects and faulting mechanism.     

粤西沿海震动图的生成和研究

震动图是描绘地震产生的地面运动和可能破坏情况的有效工具,主要包括峰值地面速度(PGV)等值线图、峰值地面加速度(PGA)等值线图和仪器烈度分布图等.基于华南数字地震台网记录到的2010年7月9日MS3.7级阳江地震的数据资料,利用SAC和GMT软件从记录到的地震波形数据提取地面运动参数,生成了PGV和PGA等值线图,并...     

数字与模拟观测系统测定地方震震级偏差研究

选用佛子岭地震台2008年9月至2009年8月记录的607个地方震事件,利用数字与模拟观测系统,对同一地震事件数字与模拟记录震级进行统计,做回归分析,计算两者偏差值,从震级偏差频次分布、震级偏差与震中距关系出发,比较差异性。结果表明,数字记录震级与模拟记录震级线性相关显著,经过拟合公式校正,固定常数校正和震中距校正,数字记录震级与模拟记录震级一致性较好。     

What is a Poor Quality Strong-Motion Record?

Some accelerograms are affected by non-standard recording and digitization problems that mean they are often not used in strong-motion studies. These non-standard problems cannot be corrected by the standard processing techniques that remove low and high-frequency noise from the time-history. Records from analogue instruments are more prone to these problems but even records from digital instruments, which are becoming increasingly common, can be affected by such errors. Since all strong-motion data is valuable it is important to know whether any useful information can be obtained from accelerograms that are affected by such problems. This article examines whether strong-motion records from analogue instruments that are missing their initial part due to late triggering of the instrument and also strong-motion records from digital instruments with low A/D converter resolution can be used for response spectral studies. It is found, by simulating such errors on high-quality strong-motion records, that good response spectral ordinates can be obtained from such `poor-quality' records within the period range of most engineering interest. This revised version was published online in July 2006 with corrections to the Cover Date.     

基于数字音频接口的地震数据采集电路板快速评估方法*

在宽频带数字地震观测技术领域,提出一种基于数字音频接口(S/PDIF接口)的数据采集电路板快速评估方法。该方法在数据采集电路设计过程中,在模拟/数字转换电路的输出端增加了一组S/PDIF数字音频接口,将模/数转换结果转换为符合音频传输标准的编码数据,并将此数据利用外置声卡同步传输到计算机,在计算机上进行数字抽取滤波、频谱分析等数据处理与解析,从而实现对地震数据采集电路板的快速评估。实验结果表明,该方法思路清晰,实现简便,结果有效可靠,能够解决常规测试评估方法中存在的问题,在高精度、高采样率数据采集技术研发和测试评估方面,具有比较强的实用性和应用前景。     

On the reliability of long‐period response spectral ordinates from digital accelerograms

Using records from co‐located broadband and digital strong motion (SM) instruments, it is first shown that the displacement waveforms obtained by double integration of the accelerogram need not be free of unrealistic baseline drift to yield reliable spectral ordinates up to at least 10 s. Secondly, to provide objective criteria for selecting reliable digital SM records for ground motion predictions at long periods, a set of synthetic accelerograms contaminated by random long‐period noise has been used, and the difference between the original accelerograms and the spurious ones in terms of response spectra has been quantified, by introducing a noise index that can be easily calculated based on the velocity waveform of the record. The results of this study suggest that high‐pass filtering the digital acceleration record from a cutoff period selected to suppress baseline drifts on the displacement waveform appears to be in most cases too conservative and unduly depletes reliable information on long‐period spectral ordinates. Copyright © 2007 John Wiley & Sons, Ltd.     

数字化噪声对强震记录的影响及其消除方法

本文详细地分析了强震加速度记录的数字化噪声。分析表明:数字化噪声由数字化设备的系统误差和操作者的随机读数误差迭加而成,随机数字化误差是具有各态历经性质的,其振幅按高斯规律分布的平稳随机过程,在其频谱组成中,长周期分量占明显的优势,因此将对二次积分加速度记录的位移曲线产生严重的影响。 研究表明:随机数字化噪声位移主要分布在周期大于25秒的频段,对加速度记录来说,分布在周期小于25秒的频段内,其随机噪声是相当小的(假定记录纸速为1厘米/秒)。因此,利用数字滤波技术,可以除去数字化加速度记录中的大部份随机数字化噪声。 作为实例,对一个典型的强震加速度记录进行了滤波,给出了低噪声的加速度记录和由此算出的位移曲线,且和未经滤波的相应记录及其位移进行了比较。      

An approach to digitize analog form of accelerograms recorded at Tarbela—Pakistan

Pakistan has a long history of seismological activity. The devastation caused by Kashmir earthquake has been administered all over the world. In Pakistan first seismological network, consisting of analog accelerograms and seismographs, was setup in early 1969 at Tarbela, where the largest water reservoir of the country is located. An approach to convert analog ground motion records into digital form is explained using a simple technique. The digitized data was compared with the original analog record and found in good agreement. The data has been used to plot response spectra. The digitized data will be available for seismic response analysis of structures and seismic risk analysis of the region.     

强震记录仪器响应失真校正的权函数方法—时域离散序列数值分析方法与应用研究之二

简要评述了现有强震记录仪器响应失真校正方法的优点和存在的不足。在文献[1]的基础上，提出了对强震记录进行仪器响应失真校正的权函数方法，并推导建立了相应的计算公式。通过设计真实地震动为已知的算例，对加速度摆和速度摆强震仪的未校正记录，和用不同方法获得的校正记录的精度（或误差）进行了对比分析。理论和算例分析表明，本文方法简单、实用，具有很高的计算机精度且无稳定性问题。     

Mixed Cadzow filtering method in fractional Fourier domain

Conventional frequency domain singular value decomposition (SVD) filtering method used in random noise attenuation processing causes bending event damage. To mitigate this problem, we present a mixed Cadzow filtering method based on fractional Fourier transform to suppress random noise in 3D seismic data. First, the seismic data is transformed to the time-frequency plane via the fractional Fourier transform. Second, based on the Eigenimage filtering method and Cadzow filtering method, the mixed high-dimensional Hankel matrix is built; then, SVD is performed. Finally, random noise is eliminated effectively by reducing the rank of the matrix. The theoretical model and real applications of the mixed filtering method in a region of Sichuan show that our method can not only suppress noise effectively but also preserve the frequency and phase of effective signals quite well and significantly improve the signal-to-noise ratio of 3D post-stack seismic data.     

对地震转换波的数字滤波处理

本文讨论运用低通滤波、偏振滤波、频率加强滤波、相关滤波及迭加处理等数字滤波方法,对地震转换波测深资料进行数字处理的方法及效果.数字滤波处理结果在一定程度上提高了记录的信噪比,为准确地进行相位对比和震相识别提供了可靠基础.