The Sensing Performance of a Novel Optical Cable for Tunnel Water Leakage Monitoring Based on Distributed Strain Sensing

To overcome the shortcomings of the existing water leakage monitoring methods for traffic and public utility tunnels, such as the high probability of missed detection and significant difficulty in automatic monitoring over a long distance, this article develops a novel strain-sensitive water leakage sensing optical cable (SL cable) and proposes a new tunnel water leakage distributed monitoring method. The effects of the leakage rate, axial load, and layout angle of the SL cable are investigated through experiments. The results indicate that the leakage area can be accurately identified and localized by the SL cable, even at a leakage rate of 2 mL/min. The average compressive strain decreases only when the tension load to the cable is exceedingly high. When the layout angle of the SL cable changes, the compression strain in the leakage area shows an uneven distribution, and the maximum compressive strain increases with the layout angle. The high sensitivity and reusability of the SL cable are verified by a repeated wetting-drying experiment. The results from experiments highlight that the proposed method has significant potential for practical implementation in water leakage monitoring.