Modeling for the design of protection structures: study of the Taconnaz avalanche site

Abstract

This article aims at showing how recent knowledge developed in the field of avalanche research can be used for a real case study, the Taconnaz avalanche path in which passive structures already exist but has to be improved. First, a morphological analysis of the site is carried out and historical data are analyzed. Second, each recorded event is back-calculated thanks to a numerical model of dense flowing avalanches and, for each surveyed avalanche, parameters at the entry of the run-out zone upstream of the defense structures are defined. Third, a statistical analysis of these parameters allows characterizing the hundred year return period events. Fourth, physical and numerical models of the dense avalanche interacting with defense structures are combined in order to design the most effective passive structure able to contain the reference avalanche. Finally, physical and numerical modelling of the interaction between the powder avalanche and the designed defense structure are performed to show that the proposed improvements do not increase the residual risk due to the powder part in areas downstream of the defense structures.