Analysis on underground water pipes multi-point leakage location method based on distributed optical fiber

Based on the principle of Raman scattering temperature measurement, a distributed optical fiber system was built to carry out the simulated leakage points location experiment of UPVC (unplasticized polyvinyl chloride) and cast-iron water pipes. Firstly, the original Anti-Stokes optical signal was filtered and smoothed. Then, the temperature measurement signal was classified and analyzed by using correlation coefficient method to identify whether the leakage occured in water pipes. Finally, the leakage points location in UVPC and cast-iron water pipes was identified by selective threshold method. The experimental results show that the distributed fiber optic system works stably and can accurately identify the leakage points of water pipes. The selective average threshold method can accurately locate the leakage points of 200 m underground water pipes and the location error ranges from 0.25 m to 0.65 m.