Item: Chute experiments on slushflow dynamics
Title: Chute experiments on slushflow dynamics
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors: C. Jaedicke, M. A. Kern, P. Gauer, M.-A. Baillifard, K. Platzer International Centre for Geohazards, Oslo, Norway Norwegian Geotechnical Institute, Oslo, Norway WSL/Swiss Federal Institute for Snow and Avalanche Research, Davos, Switzerland
Abstract: Slushflows are gravity mass flows consisting of a mixture of snow and water, which exhibit considerable damage potential for endangered areas. Small scale slushflows with a volume of 10-15 m3 were generated in the 30 m long and 2.5 m wide snow chute of the Swiss Federal Institute of Snow and Avalanche Research at Weissfluhjoch, Davos, Switzerland. Velocity profiles, dynamic pressure, basal and normal shear and flow height data were recorded in order to test suitable instruments for slushflow measurements. From the obtained data, the order of magnitude of the drag factor for slushflows interacting with obstacles could be estimated. We give an overview of the experimental setup and discuss experimental problems arising from the specific characteristics of slushflows. First results are presented, which indicate that the drag factor might be considerably higher than the estimates commonly used for dry flowing avalanches. Compared to snow avalanches, shear and normal stresses are generally higher in slushflows. The analysis of shear stress versus normal stress indicates some viscoplastic behavior. The results imply that slushflows have to be considered when choosing design criteria for avalanche protection measures wherever this kind of flows can occur. An increase in both temperature and winter precipitation could lead to more frequent slushflow events implying the need to redesign countermeasures. The results from the chute experiments are discussed with respect to development of numerical models of slushflows and a future adaptation of the optical velocity measurement devices to slushflows.
Keywords: slushflow, flow dynamics, scale experiments
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