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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
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Volume 2, issue 3/4
Nat. Hazards Earth Syst. Sci., 2, 193–202, 2002
https://doi.org/10.5194/nhess-2-193-2002
© Author(s) 2002. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.

Special issue: Landslides and related phenomena: Avalanches

Nat. Hazards Earth Syst. Sci., 2, 193–202, 2002
https://doi.org/10.5194/nhess-2-193-2002
© Author(s) 2002. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.

  31 Dec 2002

31 Dec 2002

Physical modelling of the interaction between powder avalanches and defence structures

F. Naaim-Bouvet1, M. Naaim1, M. Bacher2,1, and L. Heiligenstein1 F. Naaim-Bouvet et al.
  • 1Cemagref, Torrent and Avalanche Research Unit, 2 rue de la Papeterie, BP 76, F-38402 Saint-Martin-d’Hères, France
  • 2WLS-BOKU, Institute of Torrent and Avalanche Control, Universität für Bodenkultur, Peter-Jordanstrasse, A-1190 Vienna, Austria

Abstract. In order to better understand the interaction between powder snow avalanches and defence structures, we carried out physical experiments on small-scale models. The powder snow avalanche was simulated by a heavy salt solution in a water tank. Quasi two-dimensional and three-dimensional experiments were carried out with different catching dam heights. For the reference avalanche, the velocity just behind the nose in the head was greater than the front velocity. For the 2-D configuration, the ratio Umax/Ufront was as high as 1.6, but it depends on the height. For the 3-D configuration, this ratio differed slightly and was even greater (up to 1.8). The vertical velocity rose to 106% of the front velocity for the 3-D simulation and 74% for the 2-D simulation. The reduction in front velocity due to the presence of dams was an increasing function of the dam height. But this reduction depended on topography: dams were more effective on an open slope avalanche (3-D configuration). The ratio Umax/Ufront was an increasing function of the dam’s height and reached a value of 1.9. The obstacle led to a reduction in vertical velocity downstream of the vortex zone.

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