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Geotechnical mapping of an underground tunnel using handheld laser scanning

Point cloud model of tunnel

Point cloud model of tunnel - 2

In rock mechanics, traditional methods for on-site characterization of rock exposure typically involves manual tools and observations, such as a geological compass with inclinometer, photography, and note-taking. These traditional methods have long been known to have major drawbacks, which includes uncertainty and inaccuracy of data, time intensive, and dangers caused by physical contact with often-compromised rock faces. Tunnelling projects, in particular, pose unique challenges for in situ data acquisition due to their challenging environment, such as limited lighting and confined spaces.

Point cloud model of tunnel - 3

Coltop3D Visualization of Tunnel

To overcome the limitations of traditional geotechnical mapping methods, LiDAR has seen increased used in the industry. For rock engineering, LiDAR is favourable because it produces accurate, reliable and controllable 3D data quickly, with reduced-risk compared to traditional methods as it is a non-contact technique. Furthermore, the data can be stored and archived for further processing using various software in the future.

Capturing the tunnel construction using the Paracosm PX-80

At UAS, we employed our handheld LiDAR system, the Paracosm PX-80, to capture a tunnel construction in detailed 3D digital format (.las). Together with our client, we then used the data to detect geological features from tunnel drilling, monitor the geometry of tunnels during excavation, make deformation measurements, and extract other features. Key software used in this project includes Geo-Plus VisionLidar, CloudCompare, and Coltop3D.

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