Design of rubble mound breakwater's stability based on reliability analysis and risk assessment- Case study: Noshahr Port

Stability of the rubble mound breakwater is a very important issue in coastal and ocean engineering. It can be determined by stability number which depends on sea state and structural parameters. However, there are a lot of uncertainly in determining stability number. These uncertainties suggest that reliability analysis should be carried out for armour stones stability to ensure a desirable level of safety for breakwater. In the present study, a probabilistic framework was developed for estimating the stable armour weight placed on a rubble mound breakwater. By using this method, with a particular reliability level or expected risk, armour weight can be calculated. It is therefore, possible for design engineers to decide on the armour weight based on economical and/or construction restrictions. Application of this method was illustrated in Noshar port’s breakwater as a typical case study. The analysis yielded an almost Lognormal distribution for the armour weight. Consequently, armour weight can be assessed by analyzing the distribution based on the required reliability level. Results showed that, to get about 95% reliability, 13000 Kg weight stones must be placed at the breakwater.