Underground Vibration-Print Extraction and Spatial Attenuation Law Study of Ground-Borne Source Sensed by DAS

Abstract

Complexity of underground environment brings great challenges to vibration source detection, recognition and localization for fiber-optic distributed acoustic sensor (DAS), which utilizes the buried optical communication cable as its sensing media. In order to explore the spatial attenuation laws of the ground-borne vibration propagated through the complicated underground media to the fiber, the theoretical and experimental studies are carried out for fundamental research and underground vibration-print based on the spatial power spectral distribution is proposed to represent the spatial spectral attenuation characteristics in both the axial and radial directions. Field tests with both the narrowband and broadband vibration sources have further proved that the proposed spatial power spectral distribution can reflect the distinguishability at different radial distances well and even the event types, which contributes to improve the perception ability such as accurate two-dimensional (2-D) localization and identification with DAS.