SPATIAL ASSESSMENT OF THE FAILURE PROBABILITY OF RUBBLE-MOUND BREAKWATERS

Nowadays, many aging harbor defense structures need to be urgently upgraded, also considering the climate change- induced forcing variability (Foti et al., 2020). In particular, adaptation solutions should be designed taking into account the intrinsic uncertainty of climate projections (Morim et al., 2018), as well as the impossibility to apply the traditional design assumption of stationary forcing (Davies et al., 2017). The above-mentioned climate uncertainties, together with the non-conventional nature and the lack of geometry and material uniformity of historical or adapted structures can be properly considered only through approximated or fully probabilistic (i.e. level II and level III, respectively) design methods (Burcharth, 1987, 1993). The present work proposes the application of a probabilistic design framework based on the Monte Carlo simulation technique to existing harbor rubble-mound breakwaters and their possible upgrading solutions, considering the lack of structural and forcing uniformity along the structure. The assessment of the structure performances is carried out by iteratively calculating easy- to-use indexes for different cross-sections of the breakwater, which are representative of its uneven geometry and composition, as well as of the variable wave forcing. Then, performance spatial maps are constructed to provide a concise view of the obtained results, which can guide both the design and the decision-making processes. Here, the proposed methodology is applied to the case study of the Catania harbor breakwater (Italy).