Monitoring tunnel liners using fibre optic sensors

• Main Author: Wiyata Sadikin
• Other Authors: Yang Yaowen
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Civil engineering
• Online Access: https://hdl.handle.net/10356/163708
• Institution: Nanyang Technological University

The issue of Structural Health Monitoring (SHM) is gaining importance as a means of assessing the health of a structure by determining the amount of degradation and evaluating the remaining service life of civil infrastructure systems. The successful field implementation of SHM has not been widely achieved and is contingent upon overcoming several obstacles, namely the development and demonstration of SHM sensors with long-term stability and reliability, and the validation of the capability of SHM systems in terms of the probability of flaw detection. SHM based on modern sensor technologies has the potential to be a cost-effective method for meeting operational needs. Currently, the various kinds of Fibre Optic Sensors (FOS) are being examined as a viable load monitoring instrument. Meanwhile, the local construction authority is exploring innovative and more cost-effective materials to enhance its tunnel construction and service. One material that has been slated to be used in future projects is the Steel Fibre Reinforced Concrete (SFRC). This material has been found in previous studies to possess greater strength than the conventional precast RC segments. Therefore, the construction industry seeks to have reliable structural monitoring systems to monitor the health of the SFRC segments when they are embedded into permanent tunnel structures in the future. As such, in this report, an experimental investigation was done to explore the structural behaviour of the SFRC segment under static flexural loads with three types of FOS; namely the Fibre Bragg Grating (FBG), Distributed Fibre Optic Sensor (DFOS) and Chirped Fibre Bragg Grating (CFBG) as well as to compare the strain relationship from the data produced by these sensors. The test results are examined for trends that are consistent across each type of sensor to evaluate each other’s reliability. Ultimately, the findings from this series of tests supports the assertion that all three types of FOS tested provide reliable strain readings within the SFRC.