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![a) ALS change detection results from 2006 to 2009. b) Model output at 500 time-steps, with residual stress cells indicated in dark blue overlain on the hillshade surface topography. Key points indicated: [i] bench below the rail line, [ii] highway cut slope, [iii] steep slopes upslope of the river, and [iv] a steep slope on the east margin of the slide.](profile/Siobhan-Whadcoat/publication/342814805/figure/fig5/AS:911392072822789@1594304211650/a-ALS-change-detection-results-from-2006-to-2009-b-Model-output-at-500-time-steps.jpg)
a) ALS change detection results from 2006 to 2009. b) Model output at 500 time-steps, with residual stress cells indicated in dark blue overlain on the hillshade surface topography. Key points indicated: [i] bench below the rail line, [ii] highway cut slope, [iii] steep slopes upslope of the river, and [iv] a steep slope on the east margin of the slide.
Source publication
The upslope growth of retrogressive landslides is generally difficult to model. A cellular stress transfer model is a deterministic, numerical model that operates on a grid, and allows the patterns and underlying mechanics of movements to be explored using a reduced complexity approach. The model is time-dependent, which allows stress to transfer b...
Contexts in source publication
Context 1
... corresponds to the last ALS data collection before temporary stabilization work was started in 2011, to provide a point of comparison without significant anthropogenic changes ( Gaib et al. 2012). The emergent patterns of residual stress cells in this analysis were similar to the results shown in Figure 6. An exception was that, in this case, residual stress cells were calculated in the area near the east margin, [iv] in Figure 6, earlier in the analysis. ...
Context 2
... emergent patterns of residual stress cells in this analysis were similar to the results shown in Figure 6. An exception was that, in this case, residual stress cells were calculated in the area near the east margin, [iv] in Figure 6, earlier in the analysis. This result is likely attributed to the formation of a tension crack that is visible in the 2009 topography, leading to localized areas of steeper relative slope, in turn leading to stress concentration in this area. ...
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Citations
... Poschmann et al. (1983) described the retrogression mechanism that affects rotational slides, observing that the progressive retrogression can result in a "terraced" morphology, with counterscarps in the upper slope and remolded material in the lower slope. The retrogressive behavior of the Ten Mile Slide was also preliminarily investigated using a conceptual cellular automata model (Mitchell et al., 2018), which has highlighted the potential role of stress redistribution following the formation of slope damage within the topography. ...
The deformation and failure of slopes is associated with the formation of geomorphic features reflecting “external slope damage.” Characterizing the spatial and temporal distribution of slope damage is beneficial to understanding the mechanisms and processes underlying slope instability. To date, characterization of slope damage has predominantly been performed using qualitative approaches. In this paper, a new workflow for the quantitative, spatio-temporal characterization of the external slope damage is described and applied to the investigation of the Ten Mile Slide, an active landslide located in southern British Columbia. Since 2006, monitoring activity at the site has included periodic repeat airborne laser scanning (ALS) surveys, which have allowed the creation of a high-detail, three-dimensional database showing the progressive deformation and retrogression of the slide. External slope damage features are manually mapped in the ALS datasets, and slope damage intensity is then computed and displayed on thematic maps. The proposed workflow introduces important new slope damage measures including External Discrete Slope Damage Feature maps (EDSDF), External Slope Damage Intensity Cell (ESDICe) maps, External Slope Damage Intensity Contour (ESDICo) maps and slope damage intensity spatio-temporal plots. The new spatio-temporal damage measures are used to create damage index tables and track changes in slope damage intensity with time at any point within the slide area. The spatio-temporal analysis shows that the distribution of external slope damage features is not homogeneous across the Ten Mile Slide area. In particular, the spatio-temporal damage methodology outlines higher accumulation slope damage rates along the eastern boundary of the slide area, due to the presence of a stream incision that provides kinematic freedom and allows the lateral deformation of the slide and the formation of tensile cracking. The proposed approach in this thesis allows comprehensive, quantitative, and repeatable damage analysis to be undertaken, providing a robust method for characterizing the geomorphic evolution of slopes from a damage perspective. This research methodology provides engineers and geoscientists with a valuable tool for planning subsequent slope investigation and optimizing new or existing monitoring and early-warning systems.
