Geotechnical Applications of 3D Laser Scanning in the Active Rock Tunnel Environment 

By: Steph Fekete

Safety, long term stability and quality control in modern geotechnical projects all demand the acquisition of reliable geotechnical information for site characterization. In rock tunnel construction, documentation of rockmass character as the tunnel progresses is essential to selecting effective support and modifying excavation strategies when required. The presentation will demonstrate how the use of high definition 3-dimensional laser scanning (LiDAR) in an active tunnel environment demonstrates great potential to supplement traditional hand mapping of rock structure and character. LiDAR technology uses transmitted laser signals to record millions of highly accurate points in space to create a 3D "image" of the scanner's surroundings. The presentation will discuss the success of field work at railway tunnel sites near Oslo, Norway. Research that has followed includes developing a process of rockmass characterization with LiDAR scan data including the extraction of joint orientation, spacing and strength estimated by roughness. Lidar scan derived data is useful in creating more representative 3D discrete element rockmass models to assess structural stability as will be demonstrated.