On-site experimental study on expressway disaster identification based on ultra-weak FBG sensor array

The aging of expressways, intensified by extreme climate events, poses significant risks to safety and functionality. Real-time detection of underground defects without interrupting traffic is essential for preventing severe accidents. This study employs an Ultra-Weak Fiber Bragg Grating (UWFBG) array system to detect subgrade voids and surface sinkholes under normal traffic conditions. Two types of field tests, targeting underground voids (2 m-9 m) and surface sinkholes with suspended cables, are conducted. A scheme for underground voids inspection has been proposed and verified by 101 data samples. For suspended cable, vertical striped noise along time line can be read as typical vibration mode. A diagnostic framework and assessment criteria are developed for the large datasets generated by vehicle-induced signals in real-world situations. By integrating waveform and frequency features, the proposed method enables accurate early warnings of underground road defects without any disruption to traffic. • Vibration sensitive Ultra-Weak Fiber Bragg Grating (UWFBG) array system is deployed for several road disaster identification and early alarm of concealed void defect, avoiding any interruption and even disturbance to the traffic flow • Field tests have experimentally approved the effeteness of the proposed scheme to trace the underground void defect or the pavement collapse with exposed surviving optical cable. • Intensity-based waveforms mapping combined frequency analysis supply dimension information of the underground void defect of subgrade course, essential for the early alarm of underground hidden danger. • The diagnosis scheme of defect identification and assessment criterion for huge data from various vehicles of on-site projects are proposed.