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Bells Corners, Canada

Abellan A.,University of Lausanne | Oppikofer T.,Geological Survey of Norway | Jaboyedoff M.,University of Lausanne | Rosser N.J.,Durham University | And 2 more authors.
Earth Surface Processes and Landforms | Year: 2014

This manuscript presents a review on the application of a remote sensing technique (terrestrial laser scanning, TLS) to a well-known topic (rock slope characterization and monitoring). Although the number of publications on the use of TLS in rock slope studies has rapidly increased in the last 5-10years, little effort has been made to review the key developments, establish a code of best practice and unify future research approaches. The acquisition of dense 3D terrain information with high accuracy, high data acquisition speed and increasingly efficient post-processing workflows is helping to better quantify key parameters of rock slope instabilities across spatial and temporal scales ranging from cubic decimetres to millions of cubic metres and from hours to years, respectively. Key insights into the use of TLS in rock slope investigations include: (a) the capability of remotely obtaining the orientation of slope discontinuities, which constitutes a great step forward in rock mechanics; (b) the possibility to monitor rock slopes which allows not only the accurate quantification of rockfall rates across wide areas but also the spatio-temporal modelling of rock slope deformation with an unprecedented level of detail. Studying rock slopes using TLS presents a series of key challenges, from accounting for the fractal character of rock surface to detecting the precursory deformation that may help in the future prediction of rock failures. Further investigation on the development of new algorithms for point cloud filtering, segmentation, feature extraction, deformation tracking and change detection will significantly improve our understanding on how rock slopes behave and evolve. Perspectives include the use of new 3D sensing devices and the adaptation of techniques and methods recently developed in other disciplines as robotics and 3D computer-vision to rock slope instabilities research. © 2013 John Wiley & Sons, Ltd. Source

Lato M.J.,RockSense GeoSolutions Inc. | Diederichs M.S.,Queens University
Tunnelling and Underground Space Technology | Year: 2014

The benchmark method of measuring shotcrete thickness from 3D LiDAR and photogrammetry data involves scanning sequential blast rounds, aligning the data in a 3D environment, and calculating the spatial difference between the two models. The calculated difference between the two 3D surface models is measured as the thickness of the sprayed concrete. This methodology does not account for the convergence of the rockmass that naturally occurs between the scanning protocols, nor is it included in the difference equation, and resultantly the user over-measures the thickness of the sprayed concrete. The over-measurement can be corrected through changing the time of scanning with respect to the excavation sequence or calibrating the solution based on known rockmass convergence rates or numerical modelling. The use of 3D imaging data for the calculation of shotcrete thickness will remain a useful tool for geotechnical engineers, but corrections must made to the state-of-practice methodology in order to achieve accurate results. © 2014 Elsevier Ltd. Source

Lato M.J.,RockSense GeoSolutions Inc. | Lato M.J.,Kingston University | Jean Hutchinson D.,Kingston University | Gauthier D.,Kingston University | And 2 more authors.
Canadian Geotechnical Journal | Year: 2015

Traditional mapping and monitoring of active slope processes in mountainous terrain is challenging, given often difficult site accessibility, obstructed visibility, and high complexity of the terrain. For example, the rockfall hazard evaluation system employed by Canadian railways relies partly on visibility of the rockfall source zone from track level, which is often impossible for large or complex slopes, in the mountains and elsewhere. Recent advancements in remote sensing, data collection, and analysis algorithms have helped resolve some of these issues by allowing the slope processes to be mapped, and thereby understood, with a greater degree of accuracy and confidence than was previously possible. For example, a better understanding of the rate of movement of material around a natural rock slope affecting a transportation corridor would certainly improve any assessment of the hazards caused by those movements. Various remote sensing technologies have the capability to be used to assess these processes; however, the optimal conditions under which the technology should be deployed are not clearly defined. Between December 2012 and December 2013 the efficacy of three remote sensing technologies (terrestrial and aerial LiDAR (light detection and ranging) and terrestrial photogrammetry) were compared for their ability to detect natural and anthropogenic changes at a location along the CN railway, in British Columbia, Canada. The results demonstrate a high degree of interoperability between the different technologies, the ability to map topographical change with all three technologies, and the limitations and (or) weaknesses of each technology with respect to mapping change. The project location and site accessibility represent a real world situation with nonideal facets, which challenge the capabilities of these state-of-the-art technologies. These results will aid decisionmaking with respect to implementation of remote sensing technologies to monitor changes to rock slopes adjacent to transportation corridors, which will lead to better understanding and assessment of hazards. Source

Voge M.,Norwegian Geotechnical Institute | Lato M.J.,Norwegian Geotechnical Institute | Lato M.J.,RockSense GeoSolutions Inc. | Lato M.J.,Queens University | Diederichs M.S.,Queens University
Engineering Geology | Year: 2013

Remote sensing technologies, specifically terrestrial-based static LiDAR and photogrammetry, are transforming from state-of-the-art to state-of-practice tools for engineering geologists. The complexity of available software packages to perform standard geomechanical analyses is slowing the widespread adoption of these technologies within the geotechnical community. The development of automated processing tools for feature extraction and data interpretation is aimed at eliminating the need for complex software and manual analysis. This paper presents the development of the algorithms used in the software program PlaneDetect for the automated identification and mapping of planar discontinuities within a 3-dimensional surface model of a jointed rockmass. The software employs a five stage procedure of: surface smoothing, edge detection and masking, blast damaged detection and masking, discontinuity identification, and discontinuity set clustering. The software outputs a stereonet of discontinuity orientations colored by joint set family, an image of the 3-dimensional model with each mapped discontinuity colored by the set family, and a text file of discontinuity orientations. The results of the geomechanical analyses computed by PlaneDetect in comparison to the manual mapping results are more statistically reliable based on less user bias. The time saving realized through using PlaneDetect for mapping discontinuities is approximately ten times compared to the manual mapping approaches. © 2013 Elsevier B.V. Source

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