The Overtopping Study Of Oblique And Multidirectional Irregular Wave Action On Vertical Breakwater

In the sea dike designs, usually base on admissible overtopping measure standard for reducing the crest free board and the price of the construction, but wave overtopping significantly affects its functional efficiency, the safety of transit and mooring on the rear side, wave transmission in the sheltered area, and to some extent, the structural safety itself. Therefore, The overtopping discharge is in fact the main parameter for the design of sea dike and retaining wall. A series of hydraulic model tests has been carried out in a wave basin with the aim of studying the effect of oblique wave perpendicular attack on the wave overtopping of vertical breakwater, little research work of oblique irregular waves, especially multidirectional irregular waves attack on the wave overtopping of vertical breakwater. However, real sea waves are multidirectional and irregular, and usually attack a breakwater obliquely. It has been found that oblique waves may standing waves, and under oblique and multidirectional waves attack exert larger overtopping,. For making engineering design more economic and reasonable, besides filling up to the content of vertical breakwater in our country criterion of blank, it is necessary of the overtopping study of oblique and multidirectional irregular wave action on vertical breakwater. In this paper, the overtopping discharge of obliquity and multi-directionality action on vertical breakwater is studied systemically by a 3-D hydraulic model test.The physical model test was carried out in the multidirectional basin at the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The JONSWAP spectrum suggested by Goda was used to simulate irregular waves, and directional spreading function of Guangyi-type was used in the test. Angles of incidence varied from 0° to 45°, and three spreading extent, σ=0° , 13° , 25°, three kinds of wave steepnesses and five kinds of wave heights were tested.The effects of crest, angle, multi-directionality, depth and wave steepness on average overtopping discharge maximum overtopping per wave is presented. By use of the Ordinary Least Square Estimation (OLSE), the empirical formulate of average overtopping discharge and maximum overtopping per wave, the relation formulate of average overtopping and maximum overtopping per wave, the formulate of percentage of overtopping waves, percentage of overtopping probability distribution of overtopping per wave. The analytical method used in this paper is justified by comparing with country norm form formula results , the result of Franco et al and the result of Yuxiu Wei et al.