Forensic wedge instability-induced failure of gallery tunnel through ground-based lidar point cloud interpretation
Journal
4th ISRM Young Scholars Symposium on Rock Mechanics, YSS 2017
Journal Volume
2017-May
Pages
393-396
Date Issued
2017
Author(s)
Abstract
This study investigates the failure mechanism of a gallery tunnel. The case tunnel, built for No. 8 highway in the 1990s in eastern Taiwan, was damaged successively in 2008 and 2009. The slope above the tunnel collapsed and destroyed the tunnel more than 20 m. A great number of rock wedge with debris piled upon the damaged tunnel. Field investigation based on the ISRM suggested method regarding discontinuity in rocks indicated that there are three dominant discontinuity sets near the tunnel. However, the slope above the tunnel is steep and high, and the variation on attitudes of discontinuities were concerned for subsequent analysis. As such, a ground-based LiDAR was utilized to acquire global coordinates of the slope near the tunnel, and high precision and high density point clouds were obtained accordingly. The attitudes of fracture planes on the slope were analyzed and the stereo geographic projection analysis was used to determine the number of dominant discontinuity sets and their attitudes. A statistically hypothesis testing method was applied to examine the representativeness of the interpreted attitudes of discontinuity sets. After that, the spatial locations of wedges observed on the slope were determined accordingly. Based on the attitudes and spatial locations of rock wedge above the tunnel, the mechanism and possible influence factors that are associated with the failure of tunnel are discussed. Stability of the tunnel is also evaluated accordingly. ? 2017 by Korean Society for Rock Mechanics.
Subjects
Computer forensics; Forensic engineering; Optical radar; Rock mechanics; Rocks; Testing; Discontinuity set; Field investigation; Global coordinates; Ground-based lidars; Hypothesis testing; Point cloud; Projection analysis; Wedge failures; Failure (mechanical)
Type
conference paper