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Rockfall events constitute one of the most dangerous phenomena in mountainous areas, which can affect transportation routes. In a risk mitigation perspective, the quantification of the risk for pedestrians and vehicles represents a crucial aspect for authorities. A method tailored to these elements at risk is herein presented. The proposed method is based on a mixed formulation of the Quantitative Risk Assessment and the Event Tree Analysis approaches. According to these procedures, an accurate evaluation of the annual probability of adverse outcomes can be computed considering all the scenarios which can lead to a fatality or to an injury. Vice versa, the method lets to evaluate the allowable traffic condition, given an acceptable threshold for the risk. Furthermore, it serves to quantify the risk reduction in case of installed passive mitigation measures and, thus, to plan the priority of intervention works. An application on a study case in the Italian Alps illustrates the potentialities of the methodology. [ABSTRACT FROM AUTHOR]

Drapery meshes are protection devices installed on a cliff for mitigating rockfall hazard. They can prevent the detachment of rock fragments and control the dynamics of the falling blocks. During their design working life, drapery meshes are subjected to ageing phenomena, corrosion and impact, which can invalidate the purposes of the protection devices. A novel procedure based on a multi-hierarchical assessment of the damages is proposed. The approach is tailored for two technologies well diffused in the Alps. The main components of the system are identified and the effects of each potential damage on the overall behaviour are taken into account through risk analysis approached. A site campaign serving to test the procedure is described. The proposed approach can be modified to consider other drapery mesh installation types. [ABSTRACT FROM AUTHOR]

The study presents the dynamic structural response of steel member subjected to a localized impact from falling rock blocks in rockfall areas. A novel compliance contact model is derived for the interaction between the elastic-plastic member (the target) and an impacting rock block. Unlike other existing models, the proposed compliance contact model accurately evaluates the material properties of the rock block (considered as a deformable indenter) and of the steel target (considered as an elastic-plastic target of finite thickness). A simplified two degrees of freedom (2-DOF) lumped masses model accounting for nonlinear contact interaction and material nonlinearities is used to describe the dynamics of the phenomenon. The proposed contact law and the 2-DOF model are validated with detailed static and dynamic analyses conducted with finite element software ANSYS. The results are compared and commented in order to be implemented in future civil engineering applications. [ABSTRACT FROM AUTHOR]