ACTIONS OF SNOW AVALANCHES ON A SNOW SHED

The actions of snow avalanches on slightly inclined protection structures like snow sheds are a complex dynamic phenomenon. The impact stresses (normal and tangential) evolve not only in time but also in space. To better understand these actions so as to be able to design such structures, several studies have been conducted. Experimental measurements have been performed on a full-scale avalanche test site at Col du Lautaret (French Alps) where an instrumented plate with force sensors has been set up in an avalanche path. At each artificial release of an avalanche, the impact stresses and their temporal variations were measured. This real-scale approach is completed by a laboratory-scale experimental approach using granular flows in an inclined channel where normal and tangential forces on a basal plate are measured. The experimental results show that the impact effect is very important, particularly at the location of the rupture of slope formed by the shed. However, the stresses decrease rapidly when the distance to the rupture of slope increases. Finally, to assess the dynamic effect of the avalanche loading on the structure, dynamic simulations with a simplified multi-fiber model have been conducted. The results show that the dynamic effect is not negligible but is not critical for the structure.