Breakwaters are used to suppress the energy of waves for providing shelter to coastal and offshore facilities. Very often, the conventional rubble mound breakwaters result in high construction cost and several environmental problems, such as water contamination and wave amplification in front of the structures due to severe wave reflection. One way to alleviate the above-mentioned problem is to appropriately increase the porosity of the breakwaters. This paper aims at developing the optimum design of a porous box-type breakwater comprising multiple scrapped pipelines via physical modelling approach. Herein, the best geometrical design of the breakwater under the governing factors of porosity, width and internal tube length is proposed. A series of experiments have been conducted under the influence of regular wave environment through the analysis of wave transmission, reflection and energy loss. Several geometrical design criteria were derived to maximize the hydraulic performance of the breakwater, when adopted at sites. The proposed breakwater is a reasonably good wave attenuator and anti-reflection structure as well as an effective energy dissipator.

No abstract

No abstract

A flexible box-type floating breakwater composed of a number of membrane ballasts filled with air, water and sand has been developed for wave protection of various coastal and offshore applications. The combination of ballasts of different materials would eventually result in the same draft for all the tested models, and the performance efficiency of each breakwater model was ascertained by the means of physical modelling. A total of four rectangular breakwater models of different dynamic properties have been developed and tested in regular wave environment in a wave flume. The performance efficiency of the breakwater is determined by the wave transmission and energy dissipation characteristics. For comparison purposes, a control test model with similar dimensions is also tested in the similar test conditions. The proposed model with sand ballast at the bottom has been proven to have a higher wave attenuation capability than the other test models and the performance efficiency is comparable to that of the rigid box-type floating breakwater in some cases.