High-Speed Nondestructive Testing Methods for Mapping Voids, Debonding, Delaminations, Moisture and Other Defects Behind or Within Tunnel Linings

摘要

Tunnel linings are prone to different structural problems such as steel rebar corrosion, concrete spalling, concrete cracking, concrete delamination, and water leakage. Although time intensive and costly, visual inspection of tunnels is subjective and cannot provide information on subsurface condition. Moreover, visual inspection requires lane closures or even the entire closure of the tunnel, resulting in traffic disruption and delays. To minimize disruption, it is necessary to use nondestructive testing techniques for high speed testing of tunnel linings. This paper reviews and evaluates different high-speed nondestructive testing methods for tunnel inspection. Nondestructive testing techniques considered in this research are ground-coupled and air-coupled ground penetrating radar (GPR), digital photogrammetry, concrete surface resistivity testing, ultrasound, impulse response, impact-echo, ultrasonic surface wave, laser scanning, percometer dielectric probe technique, thermography, ultrasonic linear array, and laser scanning. Furthermore, structural health monitoring instruments such as corrosion sensors, accelerometers, strain gages, and displacement transducers are considered to allow continuous damage detection.