Recent progress of using Brillouin distributed fiber optic sensors for geotechnical health monitoring

Distributed optical fiber sensors (DOFS) have been attracted significant attention from geotechnical engineering communities for a few decades. Innovative development of structural design, encapsulation and implementation methods of optical fiber sensors leads to many new applications in geotechnical monitoring field. This paper presents a comprehensive review of Brillouin based DOFS for health monitoring of various geotechnical structures include geotextiles, soil nails, anchors, pipelines, piles, retaining walls, tunnels, and landslides. Recent application status of using two successful commercialized technologies including Brillouin Optical Time Domain Reflectometry (BOTDR) and Brillouin Optical Time Domain Analysis (BOTDA) for geotechnical health monitoring was reviewed and discussed in details. Particular emphasis was given to sensor design, encapsulation, and installation methods of DOFS in various successful geotechnical applications. Comparison analysis regarding typical advantages and limitations of different technologies (DOFS, fiber Bragg grating sensors, and conventional sensors) for geotechnical health monitoring was also presented and discussed in this paper.