FBG-based automated monitoring of long-distance tunnels

Abstract

[Objective] Long-distance tunnel engineering plays a critical role in modern infrastructure construction, where tunnel monitoring is essential to ensure safety and reliability. Traditional electrical measurement method face challenges in long-distance tunnel monitoring due to power supply constraints, data acquisition limitations, and signal attenuation over extended transmission distances. [Methods] To address these challenges, a fiber Bragg grating(FBG)-based automated multi-source monitoring and transmission scheme was proposed. An integrated monitoring system architecture was constructed, comprising perception,transmission, and application layers. Automated transmission, storage, statistical analysis, and visualization of deformation,seepage pressure, and bolt stress data were achieved through 5 G network technology and cloud platforms, enabling efficient data processing and real-time monitoring. The proposed scheme was applied to a tunnel project in Hunan, China, achieving continuous monitoring over 20 km, which validated the stability and feasibility of FBG technology in long-distance data transmission. [Results] Monitoring result indicated that fiber-optic and electrical measurements exhibited closely aligned mean values across monitoring phases, with minimum relative errors of 0. 46%, 3. 23%, and 2. 37% in displacement, seepage pressure, and bolt stress monitoring, respectively. [Conclusion] Over four months of monitoring demonstrated that fiber-optic sensing technology stably acquired and transmitted large volumes of data meeting accuracy requirements. Additionally, the proximity in data magnitudes and consistency in variation patterns between the two method confirmed the reliability of fiber-optic monitoring. The proposed FBG-based sensing scheme offers a viable new approach for safety monitoring in long-distance tunnel engineering.

Keywords

FBG / tunnel monitoring / long distance data transmission / multi-source data / automated monitoring / deformation / long distance tunnels