Investigation of the BOTDA Technology for Structural Condition Monitoring of Urban Tunnel

Structural condition monitoring of actual tunnels always needs many measured points of structural response as much as possible. The Brillouin optical time domain analysis (BOTDA) technology has obvious advantages in supplying amounts of measured points of strain along the sensing optical fibre. Therefore, the application of BOTDA technique for structural health monitoring (SHM) of an actual urban tunnel was investigated in this study. The SHM system based on BOTDA technique is designed for an actual tunnel, so this system realizes the long-distance and high spatial resolution of measured strain and temperature field of tunnel structure. And then the placement of long-distance sensing optical fibre of the actual tunnel was introduced in detail. The software system is described in the following aspects such as the function of collection, display and security diagnosis and early warning. Finally the effectiveness of the BOTDA technique for condition monitoring of actual tunnel is discussed.