The Broadband Virtual Shot Gathers Construction Based on High-Speed Train-Induced Seismic Wave

The moving high-speed train (HST) generates strong and repeatable vibrations in the railway roadbed, resulting in the propagation of complicated seismic waves into the subsurface medium. Therefore, the moving HST could be considered as a novel seismic source to detect the subsurface structure near high-speed railways (HSRs). An HST consists of several carriages. Therefore, the moving HST is one typical combined moving source that stimulates complex interference wavefields. Seismic interferometry (SI) is one commonly used method to generate virtual shot gather. However, the HST-induced seismic signal has one typical equidistant narrowband discrete (ENBD) spectrum feature, which means many frequency components are missing. Thus, the virtual shot gather based on an HST-induced seismic signal does not have sufficient bandwidth. In this study, we propose a processing scheme to construct broadband virtual shot gathers by distinguishing the moving direction of the HST and the propagation direction of seismic waves and stacking the HST events with different speeds. The feasibility of our proposed method is validated using both synthetic and real HST data, providing a broadband virtual shot gathers from HST-induced seismic signals.