Geotechnical applications of lidar scanning in tunnelling

Lidar is a remote sensing technology has been used to model geometry in a wide range of industries due to the high resolution 3-dimensional 'point clouds' produced. Advance- ments in the rate of laser scanning as well as increasing robustness and portability of the sys- tems in recent years have been sufficient to encourage its use in more hazardous and dynamic environments. Researchers from Queen's University, Kingston, have demonstrated the practical employment of successive tripod set-ups within the normal excavation cycle at a drill and blast tunnelling operation near Oslo, Norway. The use of these data sets shows much potential for geotechnical applications, both for operational/contractual information as well as geo-structural data. Operational or contractual information obtained includes: shotcrete thickness, support quality control and leakage behind the lining. Geomechanical interpretation of the tunnel lidar scans can provide: joint set orientation and spacing, structurally controlled overbreak geometry, joint roughness and identification of discontinuities visible as lineations in successive rounds.