Array measurements of S‐wave velocities from ambient vibrations
Array measurements of S‐wave velocities from ambient vibrations
复制标题
环境振动横波速度的阵列测量
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
D. Giardini
中科院分区：
文献类型：
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作者：
F. Kind;D. Fäh;D. Giardini
横波速度是局部灾害评估中一个非常重要的因素。用传统方法直接测量成本很高，因此需要廉价和有效的方法，使当地的危险评估更加可行。基于对来自小规模传感器阵列的环境振动记录的分析的技术最近变得流行。几个研究小组喜欢的一种技术是通过估计f-k谱及其S波速度结构的反演来提取频散曲线。本文介绍了从应用程序的基础上应用到测量的垂直分量的高分辨率波束形成的结果。合成环境振动产生的2-D有限差分代码被用来说明和测试的应用程序。通过叠加的随机信号，它示出的频散曲线可以被提取，即使60%的波场由空间不相关的信号。相速度误差小于10%，频散曲线可从共振基频向上提取。提供了来自两个真实的测量数据-来自靠近城市的一个地点和工业综合体内的另一个地点。反演得到的场地横波速度结构与参考资料一致。该方法的分辨率的经验法则得到证实。
SUMMARY The S-wave velocity is a very important factor in local hazard assessment. Direct measurement with conventional methods is very costly and therefore inexpensive and efficient methods are needed to make local hazard assessment more feasible. Techniques based on the analysis of recordings of ambient vibrations from small-scale arrays of sensors have become popular recently. One technique that is favoured by several research groups is the extraction of the dispersion curve by estimation of the f ‐k spectrum and its inversion for the S-wave velocity structure. This paper presents the results from an application based on high-resolution beamforming applied to the vertical component of the measurements. Synthetic ambient vibrations generated with a 2-D finite-difference code are used to illustrate and test the application. By superposition of random signals it is shown that the dispersion curve can be extracted even if 60 per cent of the wavefield consists of spatially uncorrelated signals. The errors in the phase velocities amount to less than 10 per cent. The dispersion curve can be extracted from the fundamental frequency of resonance upwards. Data from two real measurements are presented—from one site close to a city and another site within an industrial complex. The inverted S-wave velocity structures agree with reference data for the sites. The rule of thumb for the resolution of the method is confirmed.