No abstract

Abstract. This paper describes experience gained in the application of terrestrial digital photogrammetry and terrestrial laser scanning for the characterization of the structure of high mountain rock slopes and large landslides. A methodology allowing the creation and registration of 3-D models with limited access to high mountain rock slopes is developed and its accuracy verified. The importance of occlusion, ground resolution, scale and reflectivity are discussed. Special emphasis is given to the concept of observation scale and resulting scale bias and its influence on discontinuity characterization. The step-path geometry of persistent composite surfaces and its role in remote sensing measurements are described. An example of combined terrestrial digital photogrammetry and terrestrial laser scanning applied in the generation of a 3-D model of the South Peak of Turtle Mountain, the location of the Frank Slide, is presented. The advantages gained from the combined use of these techniques and the potential offered through long-range terrestrial digital photogrammetry, using high focal length lenses up to 400 mm is illustrated. Special emphasis is given to the potential of this specific technique, which has to the authors knowledge rarely been documented in the geotechnical literature.

No abstract

No abstract

Stability analysis of the 2007 Chehalis lake landslide based on long-range terrestrial photogrammetry and airborne LiDAR dataAbstract On December 4th 2007, a 3-Mm 3 landslide occurred along the northwestern shore of Chehalis Lake. The initiation zone is located at the intersection of the main valley slope and the northern sidewall of a prominent gully. The slope failure caused a displacement wave that ran up to 38m on the opposite shore of the lake. The landslide is temporally associated with a rain-onsnow meteorological event which is thought to have triggered it. This paper describes the Chehalis Lake landslide and presents a comparison of discontinuity orientation datasets obtained using three techniques: field measurements, terrestrial photogrammetric 3D models and an airborne LiDAR digital elevation model to describe the orientation and characteristics of the five discontinuity sets present. The discontinuity orientation data are used to perform kinematic, surface wedge limit equilibrium and threedimensional distinct element analyses. The kinematic and surface wedge analyses suggest that the location of the slope failure (intersection of the valley slope and a gully wall) has facilitated the development of the unstable rock mass which initiated as a planar sliding failure. Results from the three-dimensional distinct element analyses suggest that the presence, orientation and high persistence of a discontinuity set dipping obliquely to the slope were critical to the development of the landslide and led to a failure mechanism dominated by planar sliding. The threedimensional distinct element modelling also suggests that the presence of a steeply dipping discontinuity set striking perpendicular to the slope and associated with a fault exerted a significant control on the volume and extent of the failed rock mass but not on the overall stability of the slope.