3D Laser scanner and thermography for tunnel discontinuity mapping

Discontinuity mapping of tunnels during excavation is a key component of the interactive observational design approach. One requirement is to verify the geological and geomechanical predictions made at the design stage. In recent years, fully automated, remote-based techniques such as Terrestrial Laser Scanning (TLS) and Infrared Thermography (IRT) have become available, and their applications have increased, reducing the time needed to obtain complete geomechanical mapping of the rock mass. The effective use of these techniques is of great interest in tunnelling where the need arises for the operators to work close to the tunnel face. This paper presents a discussion of the main technical features of TLS and IRT, as well as data processing methods, followed by a case study of a tunnel excavated in the NW Italian Alps.