Item: Avalanche pressure at the Vallée de la Sionne test site: Comparison of maximum measured loads with design loads
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Title: Avalanche pressure at the Vallée de la Sionne test site: Comparison of maximum measured loads with design loads
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- Betty Sovilla [ WSL Institute for Snow andAvalanche Research SLF, 7260 Davos Dorf, Switzerland ]
- Micheal Kyburz [ WSL Institute for Snow andAvalanche Research SLF, 7260 Davos Dorf, Switzerland ]
- Mark Schaer [ WSL Institute for Snow andAvalanche Research SLF, 7260 Davos Dorf, Switzerland ]
- Stefan Margreth [ WSL Institute for Snow andAvalanche Research SLF, 7260 Davos Dorf, Switzerland ]
Date: 2018-10-07
Abstract: The assessment of the impact pressure exerted by avalanches on structures is an important task in avalanche engineering. Impact pressures of more than 50 avalanches were measured at the Vallée de la Sionne experimental site, in Switzerland, in the last 20 years. Measurements performed on a 20m high and 0.6m wide pylon show that the highest long-lasting bending moment is exerted by warm/wet avalanches, characterized by velocity of around 10ms, which however can develop very high flow depths, up to 7m in one of our data sets. In spite of the relatively low absolute value of pressures these avalanches exert a constant load for tens of seconds, over large depths. Conversely, the intermittency region, coupled with a dense basal layer, which characterized the front of large powder avalanches exerts the highest short-lasting bending moment. Mesoscale coherent structures which are present in this region can move with velocities up to 60ms and produce peak loads of 800-1000 kPa, which however, only last for a fraction of a second. The dense basal layer of large powder snow avalanches can also exerts a very large long-lasting pressure (up to 1000 kPa), which, however is concentrated in a thin layer close to the base of the flow, and thus contributes marginally to the overall bending moment. Finally, heavy objects transported into the flow, such as rocks, can exert large local pressure peaks that can be larger than 1000 kPa. We compare these measurements to standard calculation procedures and discuss their relevance in term of structure design.
Language of Article: English
Presenters:
Keywords: maximum impact pressure, maximum bending moment, snow avalanches.
Page Number(s): 21-25
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Digital Abstract Not Available
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