Entrainment of debris in rock avalanches: An analysis of a long run-out mechanism

Hungr, Oldrich; Evans, Stephen G.

doi:10.1130/b25362.1

Cited by 471 publications

(365 citation statements)

References 25 publications

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“…A minimum value of the pressure coefficient k appears when the flowing material extends under "active" conditions. In contrast, if the flow sheet is compressed, a maximum value results under "passive" conditions Hungr and McDougall, 2009). DAN3D uses the approach of Savage and Hutter (1989) to calculate stress ratios parallel and perpendicular to the bed (Hungr, 2008a):…”

Section: Simulation Tools and Friction Relationmentioning

confidence: 99%

“…Both simulation tools use the equivalent fluid concept (Hungr, 1995) and assume constant density and incompressibility of the flowing media as well as the validity of the shallow water approximation (i.e., negligible slope, normal accelerations). Mass and momentum balance is provided by solving the depth-averaged flow equations in a Lagrangian reference framework for DAN3D (Hungr and McDougall, 2009) and with a fixed Eulerian coordinate system for RAMMS (Christen et al, 2010b). A number of studies can be found in literature in which similar depth-averaged equations were derived, such as Iverson and Denlinger (2001) and Pastor et al (2002) for Eulerian forms, and e.g., Savage and Hutter (1989) and Gray et al (1999) for Lagrangian forms.…”

Section: Simulation Tools and Friction Relationmentioning

confidence: 99%

“…The SPH method uses the Langrangian reference frame and does not need a computational grid. DAN3D allows a selection of different types of resistance laws, including a laminar, turbulent, plastic, Bingham, frictional or Voellmy rheology (Hungr, 1995 andMcDougall, 2009 and references therein). For comparative reasons, in this study we only focused on the Voellmy rheology.…”

Section: Simulation Tools and Friction Relationmentioning

confidence: 99%

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Modeling debris-flow runout patterns on two alpine fans with different dynamic simulation models

Schraml

Thomschitz

McArdell

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Predicting potential deposition areas of future debris-flow events is important for engineering hazard assessment in alpine regions. To this end, numerical simulation models are commonly used tools. However, knowledge of appropriate model parameters is essential but often not available. In this study we use two numerical simulation models, RAMMS-DF (rapid mass movement system-debris-flow) and DAN3D (dynamic analysis of landslides in three dimensions), to back-calculate two well-documented debris-flow events in Austria and to compare the range and sensitivity of input parameters for the Voellmy flow model. All simulations are based on the same digital elevation models and similar boundary conditions. Our results show that observed deposition patterns are best matched with a parameter set of µ [-] and ξ [m s −2 ], ranging between 0.07 to 0.11 and 200 to 300 m s −2 , respectively, for RAMMS-DF, and between 0.07 to 0.08 and 300 to 400 m s −2 , respectively, for DAN3D. Sensitivity analysis shows a higher sensitivity of model parameters for the DAN3D model than for the RAMMS-DF model. This contributes to the evaluation of realistic model parameters for simulation of debris-flows in steep mountain catchments and highlights the sensitivity of the models.

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Section: Simulation Tools and Friction Relationmentioning

confidence: 99%

Section: Simulation Tools and Friction Relationmentioning

confidence: 99%

Section: Simulation Tools and Friction Relationmentioning

confidence: 99%

See 1 more Smart Citation

Modeling debris-flow runout patterns on two alpine fans with different dynamic simulation models

Schraml

Thomschitz

McArdell

et al. 2015

Nat. Hazards Earth Syst. Sci.

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“…Nevertheless, several 528 historic rock avalanches have entrained a large amount of material during runout, increasing their 529 volume and mobility substantially. Hungr and Evans (2004) reported multiple rock avalanche events 530 of various volumes which had entrainment ratios (volume entrained/collapse volume) >1, especially 531 those which interacted with colluvium, alluvium, and glacial deposits. The Komansu deposit is likely 532 to have interacted with all three of these deposits during its long runout.…”

Section: Proposed Emplacement Sequence 514mentioning

confidence: 99%

The extremely long-runout Komansu rock avalanche in the Trans Alai range, Pamir Mountains, southern Kyrgyzstan

et al. 2014

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The nal publication is available at Springer via http://dx.doi.org/10.1007/s10346-014-0492-y 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-pro t 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. Massive rock avalanches form some of the largest landslide deposits on Earth and are major 16 geohazards in high-relief mountains. This work reinterprets a previously-reported glacial deposit in 17 the Alai Valley of Kyrgyzstan as the result of an extremely long-runout, probably coseismic, rock 18 avalanche from the Komansu River catchment. Total runout of the rock avalanche is ~28 km, 19 making it one of the longest-runout subaerial non-volcanic rock avalanches thus far identified on 20Earth. This runout length appears to require a rock volume of ~20 km 3 ; however the likely source 21 zone in the Trans Alai range likely contained just ~4 km 3 of rock and presently the deposit has a 22 volume of only 3-5 km 3 ; a pure rock avalanche volume of > 10 km 3 is therefore impossible, so the 23 event was much more mobile than most non-volcanic rock avalanches. Explaining this exceptional 24 mobility is crucial for present day hazard analysis. There is unequivocal sedimentary evidence for 25 intense basal fragmentation, and the deposit in the Alai valley has prominent hummocks; these 26 indicate a rock avalanche rather than a rock-ice avalanche origin. The event occurred 5000-11000 yr 27 B.P., after the region's glaciers had begun retreating, implying that supraglacial runout was limited. 28Current volume -runout relationships suggest a maximum runout of ~10 km for a 4 km 3 rock 29 avalanche. Volcanic debris avalanches, however, are more mobile than non-volcanic rock avalanches 30 due to their much higher source water content; a rock avalanche containing a similarly high water 31 content would require a volume of about 8 km 3 to explain the extreme runout of the Komansu event. 32

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“…Indeed, numerical models do not take into account complex natural phenomena such as the static/flowing transition in granular flows or the co-existence and interaction of fluid (water, gas) (e.g. [14]; [26]; [7]; [27]; [42]; [18]; [28]; [43]; [8]; [23]). Water is almost always involved in natural landslides (e.g.…”

Section: Introductionmentioning

confidence: 99%

A two-phase shallow debris flow model with energy balance

et al. 2015

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Abstract. This paper proposes a thin layer depth-averaged two-phase model provided by a dissipative energy balance to describe avalanches of solid-fluid mixtures. This model is derived from a 3D two-phase model based on the equations proposed by Jackson [R. Jackson, The Dynamics of Fluidized Particles, 2000] which takes into account the force of buoyancy and the forces of interaction between the solid and fluid phases. Jackson's model is based on mass and momentum conservation within the two phases, i.e. two vector and two scalar equations. This system has five unknowns: the solid volume fraction, the solid and fluid pressures and the solid and fluid velocities, i.e. three scalars and two vectors. As a result, an additional equation is necessary to close the system. Surprisingly, this issue is inadequately accounted for in the models that have been developed on the basis of Jackson's work. In particular, Pitman and Le [E.B. Pitman, L. Le, Phil. Trans. R. Soc. A, 2005] replaced this closure simply by imposing an extra boundary condition. If the pressure is assumed to be hydrostatic, this condition can be considered as a closure condition. However, the corresponding model cannot account for a dissipative energy balance. We propose here a closure equation to complete Jackson's model, imposing incompressibility of the solid phase. We prove that the resulting whole 3D model is compatible with a dissipative energy balance. From this model, we deduce a 2D depth-averaged model and we also prove that the energy balance associated with this model is dissipative. Finally, we propose a numerical scheme to approximate the depth-averaged model. We present several numerical tests for the 1D case that are compared to the results of the model proposed by Pitman and Le.1991 Mathematics Subject Classification. 65C20,81T80,91B74,97M10.The dates will be set by the publisher.

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Entrainment of debris in rock avalanches: An analysis of a long run-out mechanism

Cited by 471 publications

References 25 publications

Modeling debris-flow runout patterns on two alpine fans with different dynamic simulation models

Modeling debris-flow runout patterns on two alpine fans with different dynamic simulation models

The extremely long-runout Komansu rock avalanche in the Trans Alai range, Pamir Mountains, southern Kyrgyzstan

A two-phase shallow debris flow model with energy balance

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