Experimental Research On The Wave Transmission Characteristics Of Rubble Mound Breakwaters

Rubble mound breakwaters which usually consist of core materials and armor layers are porous structures. They can allow a part of wave and flow to penetrate through and represent the most commonly used type of structure in the field of coastal and ocean engineering. The waves with much longer wave periods can transmit through the breakwaters easily. Although the transmission wave height is not very large, it has much longer wave length which has a great influence on the stability of ships in the harbors.Based on traditional structures of breakwaters adopted by many practical port projects and the proper wave conditions, this paper conducts a series of physical model experiments to study the wave transmission characteristics of rubble mound breakwaters under long period waves. And then a calculation formula for wave transmission coefficient for the practical projects is proposed. The main contents are:(1) Conduct various tests with different incident wave heights and wave periods to study the influence of wave heights and wave steepness on wave transmission coefficient;(2) By changing the water depth on the toe and breakwater width, analyze the influence of factors such as water depth and breakwater width on wave transmission;(3) Choose different sizes of core materials to study the relationship between the size of core materials and the wave transmission coefficient;(4) Based on the above test results, this paper combines with theory analysis and summarizes the calculation formulas at home and abroad to obtain the calculation formula for wave transmission coefficient;(5) Analyze the wave period change and the wave spectrum after wave transmission.The results suggest that the deep water steepness Hi/(gT2)、the relative breakwater core material width B/D as well as the relative water depth d/L have a great effect on wave transmission and calculated results are identical with the experimental results which indicates that the formula could provide a reference to practical design and study.