Investigation On Wave Reflection Of Perforated Caisson With Rubble Mound Foundation

Recently, with the development of port construction in deep water, perforated caisson as a new form of port structure become more and more popular, because it can be used to reduce wave energy and the effect of wave, it also has relatively low construction cost. Since 1961, Jarlan raised perforated caisson structures, many scholars at home and abroad studied on the reflection coefficient of perforated caisson through physical model test or numerical simulation. And some in theory, some ignored seepage characteristics of the rubble mound foundation, while nobody considered the rubble mound foundation. However, the perforated caisson usually build on the porous rubble mound foundation, and results of previous studies are different in practical application. Mostly, the experimental study of perforated caisson on the rubble mound foundation is still rare at present.Through 2-D experiment in the wave flume, analysis the relationship between reflection coefficient and its influence factors under regular wave and irregular wave. This experiment is carried out in the dimensional wave tank of Coastal and Offshore Engineering, the wave elements in test adopt common wave within engineering, included regular wave and irregular wave. Base on the previous study, this paper aims at increasing the relative height of foundation factors. The experiment is carried out under difference height of foundation, wave chamber width, porosity and wave height, in order to analyze the relationship between each factor through the single dimensional analysis.A calculation formula that through least square method(LSM) for calculating the reflection coefficient of perforated caisson with rubble foundation are proposed, which indicated relative height of foundation and relative wave chamber width with perforated caisson reflection coefficient is nonlinear, and they have greater impact on wave absorbing effect of perforated caisson. The formula is also apply to the sub-merged mound foundation. The physical experiment is valuable exploration, which can be used for engineering design and further study.Lastly, this paper calculate the reflection coefficient of perforated caisson using numerical water flume based on CLEAR-VOF method, and compared the result to the value of experiment, in order to discuss permeability of foundation impact on the reflection coefficient of perforated caisson. The study indicate that the permeability of foundation would not be ignored, and the higher of foundation, the impact get bigger.