Field and laboratory investigations of runout distances of debris flows in the Dolomites (Eastern Italian Alps)

D’Agostino, Vincenzo; Cesca, Matteo; Marchi, Lorenzo

doi:10.1016/j.geomorph.2009.06.032

Cited by 111 publications

(53 citation statements)

References 27 publications

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“…3;VAW 1992), and a comprehensive analysis of all sediment mixtures is beyond the scope of this study. The sediment mixtures used in our experiments are roughly comparable to sediment mixtures used by others (Major 1997;D'Agostino et al 2010;Scheidl et al 2013; Fig. 3).…”

Section: Experimental Debris Mixturessupporting

confidence: 72%

Debris-flow velocities and superelevation in a curved laboratory channel

2015

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Abstract:The vortex equation is often used to estimate the front velocity of debris flows using the lateral slope of the flow surface through a channel bend of a given radius. Here we report on laboratory experiments evaluating the application of the vortex equation to channelized debris flows. Systematic laboratory experiments were conducted in a 8 m long laboratory flume with a roughened bed, semi-circular cross section (top width 17 cm), and two different bend radii (1.0 and 1.5 m) with a common bend angle of 60°, and two channel inclinations (15°and 20°). Four sediment mixtures were used with systematic variations in the amount of fine sediment. In the experiments, 12 kg of water-saturated debris were released in a dam-break fashion, and multiple experiments were conducted to verify the repeatability for a given sediment mixture. Data are available for 69 experimental releases at a channel inclination of 20°and 16 releases at an inclination of 15°. Flow velocity was determined with high-speed video, and flow depth and the lateral inclination of the flow surface (superelevation) were measured using laser sensors. In general, the results from an individual sediment mixture are repeatable. We found that the channel slope as well as centerline radius have a significant influence on the correction factor k used in the vortex equation. Relatively coarse-grained sediment mixtures have larger superelevation angles than finer-grained mixtures. We found a statistically significant relation between the correction factor and Froude number. Correction factors of 1 < k < 5 were found for supercritical flow conditions. However, for subcritical flow conditions the correction factor shows a larger value as a function of the Froude number, which leads to an adaption of the forced vortex formula considering active and passive earth pressures. Finally, based on our experimental results, we present a forced vortex equation for debris-flow velocity estimation without a correction factor. Mots-clés : coulée de débris, vitesse de front de coulée, inclinaison latérale, modèle physique, équation de vortex force.

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Section: Experimental Debris Mixturessupporting

confidence: 72%

Debris-flow velocities and superelevation in a curved laboratory channel

2015

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“…Our new set of simulations also confirms that the larger the flow volume (all the other features being the same), the less mobile the center of mass of the granular flows (Okura et al, 2000;Cagnoli and Romano, 2012a;Cagnoli and Piersanti, 2015). The mobility of the center of mass is different from the mobility of the flow front, which becomes more distal as flow volume increases (Scheidegger, 1973) because the larger the flow volume, the longer the longitudinal spreading of the flow and its deposit (Davies, 1982;D'Agostino et al, 2010). This is so, in a channel for example, because the planimetric area inundated by a flow and its deposit is proportional to a power of the flow volume (Griswold and Iverson, 2008).…”

Section: Introductionsupporting

confidence: 69%

Combined effects of grain size, flow volume and channel width on geophysical flow mobility: three-dimensional discrete element modeling of dry and dense flows of angular rock fragments

Cagnoli

Piersanti

2017

Solid Earth

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Abstract. We have carried out new three-dimensional numerical simulations by using a discrete element method (DEM) to study the mobility of dry granular flows of angular rock fragments. These simulations are relevant for geophysical flows such as rock avalanches and pyroclastic flows. The model is validated by previous laboratory experiments. We confirm that (1) the finer the grain size, the larger the mobility of the center of mass of granular flows; (2) the smaller the flow volume, the larger the mobility of the center of mass of granular flows and (3) the wider the channel, the larger the mobility of the center of mass of granular flows. The grain size effect is due to the fact that finer grain size flows dissipate intrinsically less energy. This volume effect is the opposite of that experienced by the flow fronts. The original contribution of this paper consists of providing a comparison of the mobility of granular flows in six channels with a different cross section each. This results in a new scaling parameter χ that has the product of grain size and the cubic root of flow volume as the numerator and the product of channel width and flow length as the denominator. The linear correlation between the reciprocal of mobility and parameter χ is statistically highly significant. Parameter χ confirms that the mobility of the center of mass of granular flows is an increasing function of the ratio of the number of fragments per unit of flow mass to the total number of fragments in the flow. These are two characteristic numbers of particles whose effect on mobility is scale invariant.

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“…Furthermore, there are opportunities for cross-fertilisation with other fields that employ experiments with mobile sediments, including coastal wave-driven sediment transport (Hassan and Ribberink, 2005), debris flows (e.g. Goujon et al, 2007;D'Agostino et al, 2010;Iverson et al, 2010), turbidites (e.g. Postma et al, 2009;Eggenhuisen and McCaffrey, 2012), tidal experiments (e.g.…”

Section: Stream Table Setup For Bar Formationmentioning

confidence: 99%

Quantifiable effectiveness of experimental scaling of river- and delta morphodynamics and stratigraphy

Kleinhans

Dijk

Lageweg

et al. 2014

Earth-Science Reviews

121

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N. (2014) 'Quantiable eectiveness of experimental scaling of river-and delta morphodynamics and stratigraphy.', Earth-science reviews., 133 . pp. 43-61. Further information on publisher's website:http://dx.doi.org/10.1016/j.earscirev.2014.03.001Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Earth-Science Reviews. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Earth-Science Reviews, 133, June 2014, 10.1016/j.earscirev.2014.03.001. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractLaboratory experiments to simulate landscapes and stratigraphy often suffer from scale effects, because reducing lengthand time scales leads to different behaviour of water and sediment. Classically, scaling proceeded from dimensional analysis of the equations of motion and sediment transport, and minor concessions, such as vertical length scale distortion, led to acceptable results. In the past decade many experiments were done that seriously violated these scaling rules, but nevertheless produced significant and insightful results that resemble the real world in quantifiable ways.Here we focus on self-formed fluvial channels and channel patterns in experiments. The objectives of this paper are 1) to identify what aspects of scaling considerations are most important for experiments that simulate morphodynamics and stratigraphy of rivers and deltas, 2) to establish a design strategy for experiments based on a combination of relaxed classical scale rules, theory of bars and meanders, and small-scale experiments focussed at specific processes. We present a number of small laboratory setups and protocols that we use to rapidly quantify erosive and sedimentary types of forms and dynamics that develop in the landscape experiments as a function of detailed properties such as effective material strength and to assess potential scale effects. Most importantly, the width-to-depth ratio of channels determines the bar pattern and meandering tendency. The strength of floodplain material determines these channel dimensions, and theory predicts that laboratory rivers should have 1.5 times larger width-to-depth ratios for the same bar pattern. We show how floodplain formation can be controlled by a...

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Field and laboratory investigations of runout distances of debris flows in the Dolomites (Eastern Italian Alps)

Cited by 111 publications

References 27 publications

Debris-flow velocities and superelevation in a curved laboratory channel

Debris-flow velocities and superelevation in a curved laboratory channel

Combined effects of grain size, flow volume and channel width on geophysical flow mobility: three-dimensional discrete element modeling of dry and dense flows of angular rock fragments

Quantifiable effectiveness of experimental scaling of river- and delta morphodynamics and stratigraphy

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