Discontinuity pattern detection and orientation measurement for tunnel faces by using structure from motion photogrammetry

• Published in: Displays Vol. 76; p. 102356
• Main Authors: Yusoff, Intan Norsheira, Mohamad Ismail, Mohd Ashraf, Tobe, Hayato, Miyoshi, Takako, Date, Kensuke, Yokota, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2023
• Subjects: Agisoft Metashape; CloudCompare; Discontinuity pattern; Image analysis; Orientation; Structure from motion; Discontinuity pattern; Structure from motion; Image analysis; Agisoft Metashape; Orientation; CloudCompare
• ISSN: 0141-9382; 1872-7387
• DOI: 10.1016/j.displa.2022.102356

•To analyses quantitative results of discontinuity using image analysis technique.•Rock mass discontinuity detection using crack pattern analysis of tunnel face.•Development of a new quantitative discontinuity estimation towards the automation of tunnel face evaluation.•Verification of the developed assessment system of the tunnel face using the JH Rock Mass Classification system. Crack is a common condition that affects water-rich loess tunnels, and it negatively influences the reliability and safety of the tunnel. Jointed rock masses are commonly found during underground excavation. Many underground openings have failed during excavation and operation. The evaluation of tunnel faces by using a new measurement system based on structure from motion (SfM) photogrammetry is proposed in this study. The main objective is to determine the discontinuity pattern and orientation of tunnel faces as an input for tunnel face stability evaluation. A set of overlapping images obtained from a tunnel face replica using 3D polystyrene and the SfM photogrammetry approach is utilized to generate a 3D point cloud model. The discontinuity pattern and orientation are determined via facet extraction of the KD-tree plugin in CloudCompare. The same set of overlapping images is analyzed in four different quality settings (low, medium, high, and ultrahigh) with different sets of point cloud numbers that control the accuracy of the measurement of discontinuity. Results show that the high-quality setting presents a consistent measurement of the discontinuity pattern and orientation in contrast to the real 3D polystyrene tunnel face model. 2D pattern results from CloudCompare are validated using the fractal analysis method in an image analysis software, where the image is converted into a binary-one. Two sets of discontinuity are derived. The means of dip and dip direction from the cluster analysis are 82°/164° and 84°/307°, respectively. The orientations are verified through manual compass measurement. The orientations for manual compass measurement for Sets 1 and 2 are 86°/151° and 80°/303°, respectively. The discontinuities obtained from the high-quality setting of the point cloud and manual measurement of the orientation by using a geological compass highlight the similarity of the discontinuity plane in both discontinuity sets for the tunnel face replica. The proposed method for tunnel face evaluation has good judgment for tunnel support and the prevention of biased analyses by professionals.