NUMERICAL ANALYSIS OF THE STABILITY OF BREAKWATER ARMOR UNITS DUE TO SEA WAVE ATTACKS

Breakwaters play an important role in providing a calm and safe area in coastal waters. For design of these structures, the stable weight of armor units must be carefully determined which depends fundamentally on an accurate estimation of the wave forces acting on the armor units. Presently, the stable weight of breakwater armor units is determined using some empirical formulae such as Hudson [1] and van der Meer [2]. Then by conducting physical tests theaccuracy of the result is evaluated. These formulae are proposed mostly for rock stones, rather than concrete blocks. In these formulae the relationship between the magnitude of the wave forces on the armors and armor weight is not considered, rather, the wave height is used fordetermination of armor weight. Also they do not indicate the instability mode of the armour unit, i.e. uplift, sliding and overturning. A more rational approach is taking the magnitude of wave forces on the armor units into account. Few studies about the wave forces acting on armor units have been conducted so far, mostly by physical tests on submerged breakwaters (e.g. [3] and [4]). Similar researches approve that themaximum wave forces implied on the armour unit has no monotonic relations with the wave parameters, besides the fact that breaking wave causes very complex flow field near the breakwater [3, 4, 5, 6]. The novel aspect of this research is evaluating the stability of armor units based on numericallyderived wave forces which consists a solid ground for design of breakwaters instead of using empirical relations