Study On Mechanism Of Breaking Wave Loads On Vertical Walls

As an important form of coastal engineering, the vertical breakwater is being received special attentions on the force against the wall for a long time. The breaking wave has a strong impact pressure on the walls and the mechanism of breaking wave is a hot topic to be discussed because of the complexity of wave breaking process.During the experiment, break wave on the vertical wall is simulated by physical experimental method. It is the first time to do this investigation with these equipments in China. With the analysis of the flow field which are performed by using PIV(particle image velocimetry)system and the wave pressure synchronously, following conclusions could be presented.(1) By the comparison of experimental data and normative data of breaking wave, it can be investigated that experimental total force and normative total force are basically the same. However, above the static water, experimental pressure is higher than normative pressure for both cases.(2) Based on the characteristic of wave pressure, together with flow field data gained by PIV, breaking situation of breaking waves are analyzed. Breaking forms of breaking wave with medium-height mound and high mound are discussed and the reason is investigated.(3)The pressure curve is performing as a saddle with medium-height mound ,but a triangle with the high mound.(4) The analysis indicates that pressure of break wave on the vertical wall can be considered as a result of the combination of static water pressure and dynamic water pressure. When the impact is happening, there is a high velocity and the pressure is resulted by the impact pressure. The effect of the static water pressure is getting higher with the surface getting higher, and the horizontal velocity is being reduced and the impact pressure drops down rapidly.(5)The water horizontal velocity of the moment when broken water is impacting the wall, is also studied in this paper. It is shown that the water velocity is changing as a conic when the relative depthμis growing. An experienced formula of the relative depthμand the water velocity in front of the wall can be deduced based on the experimental data.