The Experimental Study Of Wave Force Acting On Perforated Caisson With Rubble Foundation

With the development of coastal engineering technology, traditional breakwaters haven't met the construction requirements. In recent decades, more and more experimental and theoretical investigations on perforated have been made by many researchers. Compared with the conventional solid structure, the perforated caisson can effectively reduce the wave reflection and the wave force. In practice, caisson is often constructed on the rubble mound foundation, while the study on perforated caisson involved in the influence of mound foundation has hardly been reported. Therefore, a systematic study on wave forces acting on perforated caisson of rubble mound foundations is very necessary and essential.Through the 2D experimental investigation in the wave flume, a systematic research on wave forces on a perforated caisson of rubble mound foundations under the condition of regular and irregular waves has been performed. Different wave conditions, model parameters and two kind of foundation height have been considered.The relationships between the total vertical force when the total horizontal force reaches its peak and the major influencing factors, such as the relative chamber width, the relative foundation height, the wave steepness, the relative depth, the porosity of perforated wall et al. are identified, using single dimensional correlation analysis method. The relationships between the total horizontal force when the total vertical force reaches its peak and the above influencing factors are also discussed with the same method. From the above analyses, the effects of the phase difference to wave force of perforated caisson can be obtained. The total horizontal force and the total vertical force don't reach it peak simultaneously and the porosity of perforated wall has great influence in the phase difference. The relationships between total moment at the back toe of a perforated and the major influencing parameters are also discussed by means of single dimensional correlation analysis method. From the above analyses, the wave steepness has significant influence over the ratios of total moment perforated and block caisson. Total moment at the back toe of a perforated caisson is rather small when the porosity is bigger. The total horizontal force and the total vertical force when the total moment at the back toe of a perforated caisson reaches its peak is smaller than their maximum, which can explain why total moment at the back toe of a perforated caisson is smaller than that of a solid caisson. By use of the Ordinary Least Square Estimation, several empirical formulae have been presented. Predicted values are compared with the measured results. It can be seen that the simplified formulae work well and can be applied in the practical engineering.