Analisi quantitativa del rischio da caduta massi tramite tecniche di modellazione numerica 3D

Rockfall risk analysis for mitigation action design requires defining rockfall hazard, the spatial probability and intensity of impacts on structures, their vulnerability, and the related expected costs for different scenarios. We integrated these tasks by using the 3D mathematical model HY-STONE. We discuss the case study of Fiumelatte (Varenna, Italy), where a large rockfall in November 2004 caused 2 deaths, the destruction of several houses and damage to transportation corridors. We calibrated a 3D rockfall numerical model by back analysis of the 2004 event, and we performed simulations for the whole area at risk by considering scenarios without protection (0), with a provisional embankment (1), and with a planned long-term protection embankment (2). The spatial distribution and energy of impacts against each exposed building have been computed and used to derive the degree of expected damage according to its vulnerability. Then, the costs and benefits associated to different scenarios and rockfall probabilities have been estimated. Our approach allows assessing both the technical and cost efficiency of different mitigation options, and shows the possibility to adopt single modelling tools to achieve quantitative evaluation of rockfall risk.