Breakwaters, as key structures in offshore engineering, play a crucial role in protecting coastlines from the destructive effects of waves. Wave overtopping, which refers to the passage of water flow over the structure, is a significant challenge in the design of these structures. This research focuses on relatively deformable and barely deformable homogeneous dual-platform breakwaters to examine the impact of geometric and environmental parameters on the average overtopping discharge. A review of previous research indicates a lack of sufficient information on how effective parameters influence wave overtopping of the structure, leading to an inability to provide efficient design solutions for such structures. To address these gaps, this study employs a systematic experimental design with an innovative geometry of a dual-platform breakwater composed of upper and lower platforms relative to the still water level. The goal of utilizing dual-platform breakwaters is to reduce the amount of required materials and optimize the structure's performance under irregular wave conditions and varying hydrodynamic circumstances.The physical models of dual-platform breakwaters were constructed and tested under irregular wave conditions with the JONSWAP spectrum in the wave channel of the Civil Engineering Department at Isfahan University of Technology. The impact of geometric parameters, including the distance between the two platforms' levels from the still water level, platform width, and structure slope, as well as environmental parameters such as wave height, wave period, and water depth in front of the structure, were meticulously tested and eva‎luated. The studies showed that increasing the dimensionless platform width and raising the still water level relative to the water surface level decreased the overall overtopping discharge. Simultaneously, the combined effects of environmental parameters like wave height and period, along with the structure's slope on overtopping discharge, were eva‎luated through new dimensionless parameters. Based on the type of wave breaking on the structure, a new two-parameter relationship for accurately predicting overtopping discharge was proposed using the wave breaking similarity parameter (ξ). Laboratory results indicated that increasing hbr, ht, Tp, Hs, and h led to higher wave run-up and subsequently increased average overtopping discharge, while increasing Bt and B resulted in reduced wave run-up and average overtopping discharge.Finally, using the provided dimensionless parameters, a practical relationship for estimating wave overtopping discharge over dual-platform breakwaters was proposed. The proposed relationships were eva‎luated using data from this study and the research of Leik Anderson and Van Gent, which fall within the dimensionless parameter range of the present research. The results from these relationships indicate the proposed relationship's adequate ability to estimate wave overtopping over dual-platform breakwaters.

محمدنويد مقيم

محمدعلي روشن ضمير , محمدعلي بدري