Detecting pre-existing HDPE double-wall corrugated drainage pipe disconnection with fiber-optic distributed acoustic sensing

The efficient and large-scale detection of pre-existing disconnections within underground drainage pipe network is crucial for enhancing the service life of these systems and improving the environmental quality of water bodies. Fiber-optic distributed acoustic sensing (DAS) has demonstrated its advantages in large-scale and long-term detection. This study proposes a novel DAS-based method for identifying pre-existing disconnections in high-density polyethylene (HDPE) double-wall corrugated pipes, a common type of drainage pipe, through controlled field experiments. An excitation device was designed to generate steady vibrational excitation at the end of the pipe. Disconnections were localized with meter-level accuracy by analyzing the time–frequency domain characteristics of signals recorded by optical cables deployed within the pipe across different lap regions, thereby validating the feasibility of DAS. Furthermore, the vibration transmission mechanism based on DAS was discussed. These findings contribute to the extensive detection of disconnections in buried HDPE pipes using DAS technology, facilitating the maintenance and upgrading of the underground drainage pipe network.