Advances in fibre-optic-based slope reinforcement monitoring: A review

Real-time assessment of slope reinforcements to diagnose their state in all stages of service life is imperative for prompt evaluation of slope stability and establishing an efficient early warning (EW) system. Many point-based monitoring instruments have been used in the last few decades. However, these sensors suffer from a particular risk of detection failures and practical limitations. Fibre-optic sensing (FOS) technologies have been developed, tested, and validated across various geoengineering applications, including slope monitoring, as they offer exceptional advantages, such as high data-carrying capacity, precise mapping of physical parameters, durability, and immunity to electromagnetic interference. The deformation of rock/soil causes the deformation and fracture of reinforcement materials, which are subsequently transferred to the encapsulated fibre-optic (FO) sensors, providing valuable information on reinforcements' safety state and performance for early failure detection. This paper is devoted to critically analysing the application of cutting-edge FOS technologies for slope reinforcement monitoring. Firstly, a concise overview of the fundamental principles underlying discrete and distributed FOS methods is provided. The key considerations for selecting FO cables and the appropriate packaging techniques necessary to withstand the challenges posed by complex geological environments are also summarised. We delve into the details of three distinct cable installation techniques within slope reinforcement components: surface bonding, slot embedment, and clamping. The recent advancements in FOS methods for monitoring slope reinforcements such as rock bolts, soil nails, anti-slide piles, geosynthetics, and retaining walls are extensively reviewed. The paper addresses this novel sensing technique's challenges and comprehensively explores its prospects. This review is anticipated to be a valuable resource for geoengineers and researchers involved in slope monitoring through FOS technology, offering insightful perspectives and guidance. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).