Evaluation of Tunnel Contour Quality Index on the Basis of Terrestrial Laser Scanning Data

Abstract The Tunnel Contour Quality Index (TCI) is an index established by Kim and Bruland for an effective management of a tunnel contour quality. It is estimated on a basis of measurements of two contour profiles within a single blasting round, using a laser profiler. However, the representativeness of measurement results obtained that way for the assessment of a contour quality of the entire blasting round is disputable. Terrestrial laser scanning (TLS) technology, combined with available numerical surface modeling tools, enables development of three-dimensional models of a monitored surface. The article reports results of TCI calculations based on TLS data. The presented TLS technique is based not only on selected cross-sections of the tunnel contour but also on the description of the morphology of the tunnel contour surface. The case study concerns measurements of the “Mały Luboń” tunnel niche, located in Naprawa, Poland. The TCI values for three blasting rounds were determined in accordance with Kim and Bruland's guidelines and were compared to TCI values determined with the proposed TLS technique. On a basis of this comparison, it can be concluded that the results obtained with the TLS technique are more reliable and representative for description of the contour quality of the entire blasting round than results obtained with the laser profiling technique.