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4D Ground Frequency Map: Concept and Application

JIANG Yiran, LIANG Xuan, NING Jieyuan, BAO Tiezhao, ZHANG Xianbing

Acta Scientiarum Naturalium Universitatis Pekinensis 2019, 55 (5): 850-858. DOI: 10.13209/j.0479-8023.2019.077

Abstract （993）

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Based on the data from the array deployed by Peking University around high-speed rail in Baoding City, Hebei Province, China, in order to obtain spectra with higher signal to noise ratio at farther stations, the paper considers the variation of train type and stacks the spectra of three components of high-speed rail seismic signal produced by the same type trains on the same station. Using the clustering algorithm, the regular pattern of how the three component spectra vary with the train type and station position is obtained. Based on the characteristics of high-speed rail seismic spectra and their variation, we propose the concept of 4D ground-frequency map, and discuss its practicability in monitoring the status of high-speed rail and its surrounding media.

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Spectral Characteristics of High-Speed Rail Seismic Signal under Viaduct

JIANG Yiran, BAO Tiezhao, NING Jieyuan, ZHANG Xianbing

Acta Scientiarum Naturalium Universitatis Pekinensis 2019, 55 (5): 829-838. DOI: 10.13209/j.0479-8023.2019.072

Abstract （1101）

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Employing a total of 10461 seismic records induced by 951 high-speed trains recorded by 11 shortperiod stations of a temporary array deployed by Peking University under the high-speed railway viaduct, we observe how the spectral characteristics vary with the speed and model of the train as well as the rail and groundsill by using a clustering algorithm K-Means. For a high-speed train in uniform motion, the spectrum of the produced seismic wave is mainly composed of nearly equally spaced peaks and its fundamental frequency is equal to the ratio of the train speed to the carriage length. By aligning the fundamental frequency, the influence of the train speed is reduced to make the spectrum pattern time-independent and easy for comparison. Clustering results show that the spectra of the high-speed rail seismic events have stable patterns when the train model, rail and groundsill conditions keep the same; the stable spectrum patterns change significantly with the change of the train model, rail and groundsill conditions. The monitoring of the stable spectral characteristics might possibly be used in safety control of high-speed rail.

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Fault Structure Detection by Matched Filter Technique

WU Mengyu, MAO Shujuan, NING Jieyuan, TANG Qijia, JIANG Yiran

Acta Scientiarum Naturalium Universitatis Pekinensis 2018, 54 (4): 730-738. DOI: 10.13209/j.0479-8023.2017.099

Abstract （760）

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Based on matched filter technique (MFT) and earthquake relative location technique, a new method is proposed to detect fault structure. The weak matched filter technique (WMFT) is modified from MFT to find more similar earthquakes, which is now used to detected events different from known templates in location. After new events are detected, their locations relative to templates can be given by using time differences from cross correlation. Due to low requirement of the WMFT in wave similarity and its low computational cost, more events can be detected and might help depict the structure of faults clearly. The feasibility of this method is primarily proved by the study of Bohai Bay area using records of 40 days.

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