Assessment of buried pipelines health condition using distributed fiber optic sensors

Natural disasters, in particular earthquakes, can cause damage to pipelines with disastrous humanitarian, social, economic, and ecologic consequences. Consequently, real-time, and automatic or on-demand assessment of damage to pipelines after the earthquake is essential for early emergency response, efficient preparation of rescue plans, and mitigation of the disastrous consequences. This paper presents the first phase of development of a method for buried pipelines health assessment based on distributed fiber optic technology, in which the sensors are both bonded to pipeline and embedded in soil. It includes determination of sensor topology, identification of required sensor properties, selection of sensors, development of installation procedures, and implementation. The first phase of the project included validation of general principles of the method through a large-scale testing. A thirteen-meter long real-size concrete segmented pipeline was assembled in a large test basin filled with soil, and tested under simulated permanent ground displacement (PGD). The basin consisted of two parts: the movable north end and the fixed south end. The movable north end of the test basin was attached to four hydraulic actuators, which were used to apply controlled displacement of the basin. As a part of validation, the results obtained from distributed sensors were compared with resistive strain gauges. The method is presented in details and results of validation test are analysed and discussed.