Prise en compte de l’effet dynamique dans les éléments constitutifs des écrans souples de filets pare-blocs

Across the country, flexible rockfall net screens are widely used as protective structures in mountainous areas subject to rock hazards. However, failures of structures following impacts have recently been observed. The lack of mobilization of energy dissipating devices, damage or even rupture of components (high-strength mesh wire and sheared anchor bar, buckled post, etc.) for stresses lower than the energy capacity of the screen raise questions about the approach currently considered for the design and sizing of these structures. The rupture of cables for translation speeds on impact higher than that retained by the regulations also questions the regulatory stress used to experimentally evaluate the characteristics of the screen. Current numerical models of net screens do not allow for the restoration of observed failures. This thesis project aims to develop a numerical model of rockfall screens that can take into account a stress closer to the real stress. However, to reproduce the observed local ruptures, it is necessary to integrate the dynamic nature of the stress in the various constituent elements of the screen. The simulation of the spatial and temporal propagation of the forces in the structure will be improved by introducing into the model the large deformations of the netting sheet and the guy wires in interaction with the dissipators whose behavior will be characterized dynamically. The malfunctions induced by a non-optimal dynamic interaction between components can thus be highlighted