2024 Volume 12 Issue 2 Article ID: 24-17197
This study investigates the impact of different seaside slope angles on breakwater stability through hydraulic model experiments conducted at a 1/50 scale. The cross-section of the breakwater was varied with slope angles represented as cot α = 1, 1.2, 4/3, 1.5, 2, where ߙ denotes the slope angle. Each trial subjected the breakwater to 1000 hits of irregular waves generated by a piston-type wave generator, with significant wave heights ranging from 11 to 17 cm and wave periods of 1.6 and 2.1 s. Stability coefficients (KD) were estimated based on Hudson’s stability equation. For a total damage rate of 1%, (KD) values were computed as 15.6, 11.3, 11.4, 8.9, and 8.4, corresponding to cot α = 1, 1.2, 4/3, 1.5, and 2, respectively. All computed (KD) values surpassed the threshold of 8.3 proposed in prior research, indicating its validity for breakwater design. However, as the slope becomes gentler, a decrease in the required mass is expected, suggesting that the Hudson equation may slightly overestimate the level of stability improvement for a gentler slope. Furthermore, the stability number (NS) was calculated using an equation that incorporates various parameters such as relative damage level, and constant values represented by ܽ and ܾ. Given the relative damage level of 0.3, 2.32 was adopted for ܽ based on previous studies, regardless of slope angles. Consequently, different β values were derived for cot α = 1, 1.2, 4/3, 1.5, and 2, yielding 1.75, 1.54, 1.60, 1.54, and 1.76, respectively. These estimated ܾ values exceeded those proposed in prior studies for all slope angles, affirming the conservative nature of the calculations.
