Abstract
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.
Highlights
TCIT and TCIR calculated according to the Terrestrial laser scanning (TLS) technique are proposed to be marked as TCIsT and TCIsR, respectively
The authors of this paper propose the TLS technique as an alternative to the laser profiling technique for the Tunnel Contour Quality Index (TCI) evaluation proposed in [1], because it enables an efficient use of large amounts of TLS data
This is due to the fact that the calculated values of the overbreak depth and the contour roughness are the lowest out of all three blasting rounds
Summary
Tunnel Contour Quality Index (TCI) is an index proposed by Kim and Bruland [1]. It is a numerical measure of the quality of a tunnel contour and was established for the effective management of a tunnel contour quality. Kim and Bruland [1] found a relationship between the TCI value and geological and operational conditions in drill and blast (D&B) tunnels. The TCI value is a function of three parameters: the overbreak depth (Od), the contour roughness (RCL), and the longitudinal overbreak variation (Vo) (Fig. 1). The TCI may be calculated for a single blasting
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