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The rheology of debris flows is difficult to characterize owing to the varied composition and to the uneven distribution of the components that may range from clay to large boulders, in addition to water. Few studies have addressed debris flow rheology from observational, experimental, and theoretical viewpoints in conjunction. We present a coupled rheological‐numerical model to characterize the debris flows in which cohesive and frictional materials are both present. As a first step, we consider small‐scale artificial debris flows in a flume with variable percentages of clay versus sand, and measure separately the rheological properties of sand–clay mixtures. A comparison with the predictions of a modified version of the numerical model BING shows a reasonable agreement between measurements and simulations. As application to a field case, we analyse a recent debris flow that occurred in Fjærland (Western Norway) for which much information is now available. The event was caused by a glacial lake outburst flood (GLOF) originating from the failure of a moraine ridge. In a previous contribution (Breien et al., Landslides, 2008 , 5: 271–280) we focused on the hydrological and geomorphological aspects. In particular we documented the marked erosion and reported the change in sediment transport during the event. In contrast to the laboratory debris flows, the presence of large boulders and the higher normal pressure inside the natural debris flow requires the introduction of a novel rheological model that distinguishes between mud‐to–clast supported material. We present simulations with a modified BING model with the new cohesive‐frictional rheology. To account for the severe erosion operated by the debris flow on the colluvial deposits of Fjærland, we also suggest a simple model for erosion and bulking along the slope path. Numerical simulations suggest that a self‐sustaining mechanism could partly explain the extreme growth of debris flows running on a soft terrain. 相似文献
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Submarine landslides and the importance of the initial sediment composition for run-out length and final deposit 总被引：1，自引：0，他引：1
Anders Elverhoi Hedda Breien Fabio V. De Blasio Carl B. Harbitz Matteo Pagliardi 《Ocean Dynamics》2010,60(4):1027-1046
Much remains to understand the dynamic processes during the flow of submarine landslides. A first relevant problem is to explain
the extraordinary mobility of submarine landslides, which has no comparison in subaerial mass movement. Another challenging
question is the apparent disparity between submarine landslides that remain compact for hundreds of kilometres and those that
disintegrate during the flow, finally evolving into turbidity currents. This problem is linked to a central ongoing debate
on the relative importance of turbidity currents versus submarine landslides in reshaping the continental margin. Based on
three epitomic case studies and on laboratory experiments with artificial debris flows of various composition, we suggest
a possible explanation for the disparity between compact and disintegrating landslides, identifying the clay-to-sand ratio
as the key control parameter. 相似文献
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Erosion and morphology of a debris flow caused by a glacial lake outburst flood,Western Norway 总被引：5，自引：2，他引：3
This article documents a 240,000-m3 debris flow resulting from a glacial lake outburst flood in Fjærland, Western Norway, May 8, 2004. The event started when a glacial lake breached a moraine ridge. The ensuing debris flow was able to erode material along its path, increasing in volume from about 25,000 to 240,000 m3 before depositing about 3 km from its starting point. Field investigations, pre- and post-flow aerial photographs as well as airborne laser scanning (LIDAR) were used to describe and investigate the flow. The most striking and unusual feature of this case study is the very pronounced erosion and bulking. We have made a detailed study of this aspect. Erosion and entrainment is quantified and the final volume of the debris flow is determined. We also present geometrical and sedimentological features of the final deposit. Based on the Fjærland data, we suggest that a self-sustaining mechanism might partly explain the extreme growth of debris flows traversing soft terrain. 相似文献
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