Effects of eccentric impacts and corrosion on the structural behaviour of retaining wire ring nets

Anti-submarine (ASM) ring nets are fundamental components for various passive solutions to mitigate rockfall hazard. While numerical models could accurately assess their performance for all the applications, the modelling of a whole system comprising the net is time-consuming. An analytical model of wire ring nets currently on the market, applicable to the different configurations, can thus represent a profitable tool to investigate the performance of nets used in retaining systems. Currently, for flexible rockfall barriers the whole system structural behaviour is evaluated with real tests impact tests performed in the centre of the system, only, possibly overestimating the system capacity and consequently underestimating the residual risk at installation sites. An analytical model is proposed in this paper with the aim to evaluate the mechanical behaviour of wire ring nets for eccentric impacts too. The model validation is performed using quasi-static experimental punching tests results related to both rigid and flexible boundaries conditions for the centred impact case, while numerical models, realized applying well-established approaches, strengthen the model validation for eccentric impacts. Analyses performed during the barrier design phase and its service life enable to assess the real efficiency of retaining systems.