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Detection of urban underground cavities using seismic scattered waves: a case study along the Xuzhou Metro Line 1 in China
Author(s) -
Zhang Jun,
Liu Shengdong,
Yang Cai,
Liu Xue,
Wang Bo
Publication year - 2021
Publication title -
near surface geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.639
H-Index - 39
eISSN - 1873-0604
pISSN - 1569-4445
DOI - 10.1002/nsg.12132
Subject(s) - offset (computer science) , geology , borehole , economic geology , seismic migration , environmental geology , seismology , engineering geology , regional geology , gemology , acoustics , geotechnical engineering , computer science , physics , metamorphic petrology , volcanism , telmatology , tectonics , programming language
ABSTRACT During metro construction, unidentified cavities pose a serious threat to the integrity of the tunnels and public safety. An efficient and accurate cavity‐detection method is needed, given the limited space and time constraints of urban construction. Equivalent offset migration is a high‐accuracy, seismic scattered‐wave imaging method that is effective in wavefield extraction, has the ability to derive the wavefield outside the range of the source–receiver points and can use imaging data for areas with poor signal‐to‐noise ratios. In this study, we consider a stratified subsurface structure and the geological conditions of a city and construct a typical urban cavity geological model to study the characteristics of cavity‐scattered waves. In numerical studies, equivalent offset migration is superior to Kirchhoff post‐stack migration in the case of seismic scattered‐wave imaging. A fast‐moving detection device for urban construction conditions is designed to meet the data‐acquisition requirements on the basis of the scattered‐wave characteristics and equivalent offset migration method. Efficient acquisition and accurate detection are confirmed, with the detected depth deviating by less than 1 m compared to the depth obtained from borehole checks along the Xuzhou Metro Line 1 in China. The results show that cavity detection using seismic scattered waves can meet urban engineering requirements. Further study on the design of a high‐performance detection device, reception and extraction of weakly scattered waves, and scattered‐wave recognition and interpretation techniques for different targets will be helpful in solving cavity‐detection problems in urban engineering.