Study On Hydrodynamic Characteristics Of Pontoon Type Floating Breakwater

Over population and environment pollution have increasingly threatened human beingsaround the world. Recently, using marine space instead of land space has been attracted as aneco-friendly alternative. The floating breakwater is a structure which can protect the port andcoastal from wave actions. Compared with the traditional base forms, it has the advantages ofeconomics, light weight, mobility, and nice flexibility to groundwork and so on.Laboratory physical model tests were performed to study the hydrodynamicperformances (include wave attenuation, wave forces, mooring forces) of pontoon typefloating breakwater under regular wave. Influence of model parameters (wave steepness,relative width, stiffness of mooring chain, angles between mooring line and horizontal line atthe joint, the pre-tensioned, the wave dissipating perforation) on hydrodynamic performancesare discussed. The results revealed that:The floating breakwater’s body-length is the most important factor in affecting the wavedissipation and the transmission coefficient reduces with its increasing. In the condition ofthis experiment, when its body-length increase from 0.25m to 0.42m, the transmissioncoefficient reduce 10％. The wave steepness also was an important reason; the transmissioncoefficient, the mooring forces and the wave forces are all increasing with its increasing. Theoffshore side mooring force F1is always greater than the onshore side mooring force F2.There is a best angles between mooring line and horizontal line, when theαbetween 45°and68.8°,which gives birth to the smallest transmission coefficient and smaller wave forces.The pretension of the mooring lines is an important factor in affecting the mooring forceand the mooring force increasing when the mooring line was been pre-tensioned. Mooringforces (including offside mooring force, onside mooring force and total mooring force)increasing with the stiffness of mooring chain’s increasing.