Pressure of snow avalanches against buildings

The paper aims to analyse the effects of topography and building position on the magnitude of pressure exerted by snow avalanches against buildings, through a structural back analysis and nu- merical fluid-dynamics. Studying a real snow avalanche impact occurred in 2008 which destroyed a village in Valsavarenche (Aosta Valley - IT), the attention is focused on the avalanche flow deviation caused by the destructive interaction with a first building, which protected part of a second building beyond it. By means of photographical and in situ survey, a detailed description of avalanche geomet- rical, dynamical and physical properties is outlined. A structural investigation, based both on debris arrangement and on measurements on the undamaged parts of buildings is also carried out. Thus, a back analysis is carried out in order to define collapse dynamics and to estimate the upper and the lower bound of impact pressure. Afterwards, numerical fluid-dynamical analyses are per- formed to simulate different impact scenarios and to understand the effects of obstacles on avalanche behavior: a qualitative measure of the interactions among buildings, which may mutually protect one another, is obtained.