Distributed optical fiber bi-directional strain sensor for gas trunk pipelines

In this paper, we designed an optical fiber bidirectional strain gauge bonded on each single detecting point. Based on detecting single point of markedly different value from the remainder of the fiber, the loss-modulation approach is appropriately applied to monitoring the strain/deflection of pipelines in OTDR. It is worth noting that the distortion of pipelines can be measured partly by detecting the strain at the joint suitable to monitor gas trunk pipelines. The key technology for measuring both tensile strain and compressive strain is the pretreatment of bending the optical fibers on the two pairs of bending points, which can be identified by optical time domain reflectometer (OTDR) if inserting time delay optical fiber.