عنوان مقاله [English]
Rubble-mound breakwaters are common marine structures, which make a calm and safe area for ships to berth. To protect these structures from sea wave attack, armoured layers consisting of rocks or concrete blocks are put on their outer surface. Providing the stability of an armour layer is of great importance in the design of breakwaters. Until now, design of the armour layer has been based on empirical formulae and physical tests. In these conventional approaches, wave parameters are correlated to the armor weight. The current research aims to study the stability of the armour layer by a numerical method, employing the commercial code FLOW-3D. In the present research, the effects of geometrical parameters, such as breakwater slope and armour diameter and, also, physical parameters, such as wave height and period and still water depth, on the stability of the armour, are studied. For this purpose, four locations consisting of breakwater toe, still -water level and maximum of wave run-up and run-down levels are selected for placement of the armour. The breakwater is assumed to be high-crested and trapezoidal in shape. The armours are cubical and rigid. Also, monochromic waves are used in this study. Analyses are undertaken to determine forces and moments acting on the armour, which is assumed to have no interlocking between it for the sake of simplicity. The results show that wave breaking type has an important effect on the force and stability of the armour. Also, results indicate that the armour placed in the still water and maximum wave run-down levels are subjected to the most severe wave forces. Finally, some formulae are presented for computing wave forces, moments and stability numbers for armour blocks in different locations. Using these formulae allows the user to compare the stability modes of the armour for different wave characteristics.