Effect of different antifer unit placement methods on wave overtopping

Erler, Berkay
Along with stability, the most important criterion in the design of rubble mound breakwaters is the serviceability, which is mostly determined based on wave overtopping. Wave overtopping discharges are generally estimated using available empirical formulas in the literature. The effect of different armor units on wave overtopping are reflected utilizing roughness coefficients (f) in these empirical formulas in the widely accepted design specifications. However, the effect of different placement methods of these units are not completely addressed and discussed. In this study, the effect of different placement methods of antifer units on wave overtopping were investigated. For this purpose, an experimental study was carried out at Middle East Technical University, Department of Civil Engineering, Coastal and Ocean Engineering Laboratory wave flume on a conventional rubble mound breakwater cross-section constructed using antifer units having a 1:2 face slope and crown walls with varying crest heights (Rc).The different antifer placement methods proposed in the literature, namely closed pyramid, double pyramid (regular and staggered) and irregular placement methods were utilized, and experiments were carried out in a total of eight different armor layers by also considering different packing densities in each placement method. Wave steepnesses (Hm0/Lm-1,0) between 0.025 and 0.038 and relative crest freeboards (Rc/Hm0) between 0.68 and 1.85 were tested for each armor layer under five different irregular wave series. Results of experimental studies show that different antifer unit placement methods and packing densities significantly change the wave overtopping discharges. It is observed that the mean wave overtopping rate obtained when antifer units are placed with the regular double pyramid placement method is 100% higher than the irregular placement method for the same packing density. Based on the experimental results, new roughness coefficients (f) are proposed for different antifer unit placement methods.
Citation Formats
B. Erler, “Effect of different antifer unit placement methods on wave overtopping,” M.S. - Master of Science, Middle East Technical University, 2023.