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As the first step in investigating the possibility of using a distributed fibre optic strain sensing system to detect changes in the state of an underground mine resulting from mining activities, we constructed an underground mine monitoring system based on a Brillouin optical time domain reflectometer (BOTDR) system in the El Teniente mine and conducted a field trial. This paper describes the structure of and mining processes in the mine, outlines the underground mine monitoring system that we developed and constructed, and presents some monitoring results. We consider from the results of the half-year field trial that the system could detect the deformation in a tunnel in the underground mine ventilation level due to a stress distribution imbalance produced surrounding the undercut face and the large-scale ore extraction area. The monitoring system using the BOTDR-based distributed fibre optic strain sensing system can be regarded as promising for underground mine monitoring. [ABSTRACT FROM AUTHOR] more...

The article offers information on the development of technology for the repair and reinforcement of concrete manhole and tunnel structures by NTT Access Network Service Systems Laboratories in Japan. Topics include the degradation of steel reinforced concrete manholes, evaluation methods for the maintenance of manholes, and shield tunnel maintenance and management. It also discusses the deterioration of aging infrastructure such as cut-and-cover and shield tunnels. more...