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In recent years, it is becoming more common to use fiber optic sensors (FOS) in the structural health monitoring (SHM)
sector, especially in the civil engineering field. A number of surface-mountable sensor system for FOS have been
developed in the past years, the recent development of Brillouin Optical Time Domain Reflectometry (BOTDR) was a
great evolution towards the SHM system development, it inspired the new edge of FOS SHM system. Different from the
traditional monitoring instruments, it provides distributed, long distance, real-time, interference free and high
accuracy/precision measurement data. It is now possible to achieve "continuous" measurement data and this SHM
technique is applicable in area that is inaccessible. The research aims to solve the problems which exist in the
convergence measurement using the conventional measuring methods, however, there is still a gap between the lab
experiments and field applications. Limited research has been conducted on how to maximize its possible applications
due to its brittle and fragile material nature. A number of additional considerations for a successful pairing of these two
must be taken into account for successful field applications. This article provides a short review on underground
monitoring techniques and FOS SHM systems. The focuses is on examine (i) the feasibility and effectiveness of different
BOTDR sensors installation methods (ii) the suitable commercially-available o sensing cable for underground
application (iii) the sensing performance of customized sensor protection package BOTDR sensor that manufactured
involving layers of fiber reinforced composites. This research serves a bridge in between the technology advancement to
the creation of a structure health monitoring system with practical application, numerical simulation and theoretical
analysis aspects, and also to provide the insights into the mechanisms of BOTDR.
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