Application of distributed optical fiber acoustic sensing system in pre-stressed concrete cylinder pipe (PCCP) pipeline structure health monitoring

The structural health monitoring of Prestressed Concrete Cylinder Pipes (PCCP) is still a difficult issue because the existing detection methods and pipeline protection methods require pipelines to stop running for detection and maintenance, and cannot monitor the running status of pipelines online in real time. As a result, it is impossible to prevent pipeline damage timely and effective and prevent third-party intrusion and damage. Aiming at problems such as PCCP pipeline leakage and pipe burst caused by the external third-party intrusion, pipeline aging, and other factors, this paper proposes a distributed fiber-optic acoustic sensing monitoring method based on the combination of fiber-optic back Rayleigh scattering and phase-sensitive optical time-domain reflectometry. When the pipeline is running normally, by collecting and demodulating the vibration, sound, positioning information and other data along the vibrating optical cable laid on the pipeline, the monitoring and rapid positioning of the pipeline intrusion damage and broken wire can be realized, to achieve the effect of real-time online monitoring of the structural health of the pipeline. The simulation test results show that the system can monitor the length of the pipeline up to 50km, the fault location accuracy is less than 5m, and the system has a single-point listening function, which can realize the secondary review of the fault point alarm information.