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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Modelling a cohesive-frictional debris flow: An experimental, theoretical, and field-based study
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Modelling a cohesive-frictional debris flow: An experimental, theoretical, and field-based study

机译：建模内聚摩擦性泥石流：基于实验，理论和现场的研究

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摘要

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 Fj?rland (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 etal., 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 Fj?rland, 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.
机译：由于水的成分变化和成分分布不均匀，泥石流的流变学难以表征，这些成分的分布范围可能从粘土到大石块。很少有研究从观察，实验和理论的角度来研究泥石流的流变学。我们提出了一种流变-数值耦合模型，以表征其中存在内聚和摩擦材料的泥石流。作为第一步，我们考虑了小规模的人工泥石流在具有可变的粘土与沙子百分比的水槽中，并分别测量了沙子-粘土混合物的流变特性。与数值模型BING的修改版本的预测结果进行比较，可以得出测量结果与模拟结果之间的合理一致性。作为现场案例的应用，我们分析了最近在Fj？rland（挪威西部）发生的泥石流，该泥石流现在可以获得很多信息。该事件是由于冰ora山脊破裂导致的冰川湖爆发洪水（GLOF）引起的。在以前的贡献中（Breien等人，Landslides，2008，5：271-280），我们专注于水文和地貌方面。特别是，我们记录了明显的侵蚀，并报告了事件期间沉积物迁移的变化。与实验室泥石流相反，天然泥石流内部存在大块巨石和较高的正常压力，因此需要引入一种新颖的流变模型，以区别泥浆与碎屑支撑的材料。我们用改进的BING模型和新的内聚摩擦流变学进行仿真。为了解决由Fj？rland的冲积沉积物上的泥石流引起的严重侵蚀，我们还提出了一个简单的坡度路径上的侵蚀和膨胀模型。数值模拟表明，一种自我维持的机制可以部分解释在软土地上流动的泥石流的极端增长。

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