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DETECTION OF ROCK SLOPE FAILURE PRECURSORS USING A TERRESTRIAL LASER SCANNER
Session: Landslides and Slope Stability II / Mouvements de terrain et stabilité des pentes II
Ryan Kromer, Queens University (Canada)
Jean Hutchinson, Queens University (Canada)
Matt Lato, BGC Engineering (Canada)
Dave Gauthier, BGC Engineering (Canada)
Tom Edwards , CN Rail (Canada)
In this study, we monitored a slope along the CN Rail line in the Fraser River Valley, BC using terrestrial laser scanning (TLS) to: identify rockfall source areas based on precursor deformation, track the deforming areas in 3D, project their potential volumes and provide early warning to the railway prior to rockfall. We identified three areas of deformation, between December 2013 and June 2014, the largest having a potential failure volume of 4800 m3. Three-dimensional tracking of this block allowed us to identify the failure kinematics prior to failure of the largest block, a wedge type failure plunging at 14o with a vector deformation magnitude of 0.1 m. In September of 2014, we gave warning to the railway of the potential rockfall volume and of the kinematics for the largest identified area. We continued to monitor the deforming areas of the slope until all three rockfalls occurred, in December 2014 after a large rainfall event. We collected oblique helicopter photos for photogrammetric analysis three days post failure and calculated a depletion area volume for the largest block of 4200 m3 and volumes of 210 and 220 m3 for the smaller two deforming areas.
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