Experimental Study On Pile-restrained Pontoon-plates Floating Breakwater

In recent years, the application of floating breakwaters has been more and more brought to people's attention because of their simple structure, inexpensive cost, nice flexibility to groundwork, easy relocation and so on. But the transmission rate of such breakwater to long waves (L/B>6) is still high, which is the main reason that restricts the floating breakwater to work as a permanent wave attenuation equipment, so it is necessary to design a new structure having good attenuation performance to long waves.In the present paper, a new kind of floating breakwater, pile-restrained pontoon-plates structure, is proposed. In this structure, to improve wave attenuation performance, the motion of water mass is disturbed by the plate under the pontoon, and the sway and roll of the structure is restricted by vertical pile anchor. Laboratory physical model tests were performed to study the wave attenuation performance and heave motion response of three kinds of pontoon-plates models and one pontoon model, influence of model geometric parameters (relative pontoon width, plate width, number of plates, pontoon draft and distance between pontoon and plate) on wave attenuation performance and heave motion response are discussed, as well as the relationship between wave attenuation performance and heave motion response.The result indicates that the wave attenuation performance of the new structure proposed in the present paper is better than pontoon structure, because its transmission coefficient is 0.2~0.3 smaller and that the heave motion is 0.1～0.2 time of incident wave height smaller.The plate width has significant influence on the transmission coefficient of middle-period wave and on the heave motion of long-period wave. The effects of pontoon draft and number of plates are unobvious. The distance between pontoon and plate has little effect on wave attenuation but obvious influence on heave motion.With the increasing heave motion of this floating breakwater, the transmission coefficient increases, and the reflection coefficient and the wave dissipation coefficient decrease...