International Symposium on Mitigative Measures against Snow ...

<strong>International</strong> <strong>Symposium</strong> on Mitigative Measures against Snow Avalanches
Egilsstaðir, Iceland, March 11–14, 2008
The accidental actions with a return period of 300 years are approximately by a factor of 1.6
larger compared to the variable action with a return period of 30 years. The data of Table 4
demonstrate clearly that it is not advisable to work with standard loads because the loads
depend very much on the site characteristics.
4. CONCLUSIONS
With the performed experiments on the laboratory chute as well as on the Weissfluhjoch
chute, it was possible to improve the calculation formula of the guidelines. Especially new
findings on the snow densities, the coefficients of friction and the formula to calculate the
deviation force could be introduced. The realisation of the experiments on the snow chute was
more demanding than previously assumed, especially the repeatability was not perfect
because of the varying types of snow. An important point that should be studied in more
details in the future, is the influence of a snow cover or of avalanche deposits on the damping
of the dynamic avalanche loads. In addition, the distribution of the force could be measured
with a higher resolution using more and smaller load plates after the deviation point. The new
findings proposed in this paper are mainly based on scaled experiments. It would be desirable
to verify the results with full-scale experiments on real snow sheds. However, such
experiments are quite costly because an extensive instrumentation with load plates, snow
depth gauges and velocity measurements is necessary. Further, the avalanche frequency
should be high to have a complete data set – and it should be taken into account that
avalanche deposits on the load plates can prevent good measurements as we have learned
from the Valleé de la Sionne avalanche test site.
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