Distributed Sensing of Circumferential Strain Using Fiber Optics during Full-Scale Buried Pipe Experiments

As buried infrastructure in North America and around the world reaches the end of its service life, engineers and infrastructure managers will require an improved understanding of the performance of both deteriorated pipes and repair techniques. To develop this improved understanding, sensing technologies that enable the full pipe behavior to be measured, rather than a small number of localized discrete measurements, are required. A possible solution to this problem is to use distributed fiber optic strain sensors. To this end, a series of buried pipe tests were undertaken on steel, concrete, and high-density polyethylene (HDPE) pipes instrumented with distributed fiber optic strain sensors. The distributed measurements were in agreement with conventional strain gauges, but enabled the full strain distribution around the circumference of the pipe to be measured. This allowed localized behavior that would have been missed with conventional strain gauges to be detected and quantified. In addition, the choice of fiber optic cable proved to be an important consideration due to a trade-off between measurement accuracy and sensor robustness.