Simulations of dense-snow avalanches on deflecting dams

Irgens, Fridtjov; Schieldrop, Bonsak; Harbitz, C. B.; Domaas, Ulrik; Opsahl, Runar

doi:10.3189/1998aog26-1-265-271

Cited by 4 publications

(4 citation statements)

References 9 publications

(14 reference statements)

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“…More elaborate descriptions of the flow of an avalanche against a dam are given by McGlung and Mears (1995) and Irgens and others (1998). Laboratory scale-model experiments have also been used to study the flow of avalanches that hit deflecting and catching dams (Chu and others, 1995; Tai and others, 2001).…”

Section: Introductionmentioning

confidence: 99%

Run-up of two avalanches on the deflecting dams at Flateyri, northwestern Iceland

Jøhannesson

2001

Ann. Glaciol.

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Two deflecting dams were constructed above the village Flateyri, northwestern Iceland, after the catastrophic avalanche accident on 26 October 1995 when 20 people were killed. Both deflectors have since been hit by moderately large avalanches, in each case with a volume of > 100 000 m3 and an estimated return period of 10–30 years. The avalanches hit the deflectors with deflecting angles of 20–25° and a maximum run-up of 12–13 m. They flowed about 500 m along the deflectors after the initial impact and terminated in the ocean on the respective sides of the reef where the village is situated. Back-calculated impact velocities are of the order of 30 m s–1. In both cases, the impact channelized a part of or The whole of the width of the avalanche into a stream 20–80 m wide, the run-out of which is estimated to have been increased by > 100 m by the deflection of the avalanche by the dam. Although the avalanches are much smaller than the design avalanches of the deflecting dams, they have provided avalanche professionals and the public in Iceland with much-welcomed direct evidence of the effectiveness of the defence structures at Flateyri against moderately sized events. They also provide unique direct observations for further scientific investigations of the deflection of avalanches by man-made deflecting dams.

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Section: Introductionmentioning

confidence: 99%

Run-up of two avalanches on the deflecting dams at Flateyri, northwestern Iceland

Jøhannesson

2001

Ann. Glaciol.

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“…The sign of the friction term is an important element of the theory. Below I describe field examples from Flateyri, Iceland, in 1995 (see also Appendix B) and Vassdalen, Norway, in 1986 where the sgn function is estimated to be + 1 for the highly destructive, fast moving Flateyri avalanche and -1 for the slower moving Vassdalen avalanche [Irgens et al, 1998].…”

Section: Derivation For Dry Frictional Materials' Dense Dry Flowing mentioning

confidence: 99%

Superelevation of flowing avalanches around curved channel bends

McClung¹

2001

J. Geophys. Res.

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Abstract. Flowing avalanches are those with a dense core of flowing granular material at the base, which dominates the dynamics causing friction. Sometimes when avalanches descend, they encounter curved channel bends, which cause the flowing material to superelevate or climb up on the wall of the channel bend so that the level of the flowing snow is higher on the outside of the bend than at the center of the channel. This can provide important information about avalanche speeds. The conventional approach for estimating speeds is mathematically equivalent to one developed from equations based on fluid mechanics with a balance between fluid pressure force and centrifugal force to yield a simple expression which relates channel radius, avalanche speed, and superelevation geometry. In this paper, the conventional theory is replaced by one which relates avalanche speed to basal friction (as appropriate for flowing snow), passive snow pressure (accounting for friction between snow particles), channel radius, and superelevation geometry. It is shown that the conventional theory is physically unrealistic for flowing snow modeled as a frictional material. Also, the conventional theory will result in lower speed estimates than the new formulation for the same amount of superelevation.

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“…The influence of obstacles on avalanche flows has been the topic of many recent studies combining full-scale observations on snow avalanches, small-scale experiments with granular materials, theory and numerical modelling. Studies refer to avalanche flows interacting with deflecting dams (Irgens and others, 1998; Johannesson, 2001; Hakonardottir and Hogg, 2005; Cui and others, 2007; Faug and others, 2007; Gray and Cui, 2007), catching dams (Chu and others, 1995; McClung and Mears, 1995; Naaim and others, 2004; Gauer and others, 2007, 2009; Faug and others, 2008a,b) and retarding mounds (Hákonardóttir and others, 2003; Chiou and others, 2005). Up to now the particular situation of free-surface flows overflowing a catching dam has been addressed in terms of the run-out shortening downstream of the dam (Faug and others, 2008a,b).…”

Section: Introductionmentioning

confidence: 99%

A simple analytical model for pressure on obstacles induced by snow avalanches

Faug¹,

Chanut²,

Beguin³

et al. 2010

Ann. Glaciol.

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ABSTRACT. The forces snow avalanches are able to exert on protection dams or buildings are of crucial interest in order to improve avalanche mitigation measures and to quantify the mechanical vulnerability of structures likely to be damaged by snow avalanches. This paper presents an analytical model that is able to calculate these forces taking into account dead-zone mechanisms. First, we present a 2-D analytical hydrodynamic model describing the forces on a wall overflown by gravity-driven flows down an inclined plane. Second, the 2-D model is successfully validated on discrete simulations of granular flows. Third, we provide ingredients to extend the 2-D model to flows of dry and cold snow. Fourth, we propose a simplified 3-D analytical model taking into account lateral fluxes. Finally, the predictions from the simplified 3-D analytical model are successfully compared to recent measurements on two full-scale snow avalanches released at the Lautaret site in France.

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Simulations of dense-snow avalanches on deflecting dams

Cited by 4 publications

References 9 publications

Run-up of two avalanches on the deflecting dams at Flateyri, northwestern Iceland

Run-up of two avalanches on the deflecting dams at Flateyri, northwestern Iceland

Superelevation of flowing avalanches around curved channel bends

A simple analytical model for pressure on obstacles induced by snow avalanches

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