A review of previous studies on the applications of fiber optic sensing technologies in geotechnical monitoring

Geotechnical engineering is characterized by many uncertainties, including soil material properties, environmental effects, and engineering design and construction, which bring a significant challenge to geotechnical monitoring. However, conventional sensors with several inherent limitations, such as electromagnetic interference, signal loss in long-distance transmission, and low durability in harsh environments cannot fully meet current monitoring needs. Recently, fiber optic sensing technologies have been successfully applied in geotechnical monitoring due to the significant advantages of anti-electromagnetic interference, stable signal long-distance transmission, high durability, high sensitivity, and lightweight, which can be considered an ideal replacement for conventional sensors. In this paper, the working principle of different fiber optic sensing technologies, the development of fiber optic-based sensors, and the recent application status of these sensing technologies for geotechnical monitoring were comprehensively reviewed and discussed in detail. Finally, the challenges and countermeasures of the sensing technologies in geotechnical monitoring were also presented and discussed.