Experimental And Numerical Investigation Of Wave Forces On Quasi-ellipse Caisson

At present, the open wharves are often constructed in the deep water regions that keep far away from the seashore for the large ships, in order to cut the investment cost and shorten the construction period. Quasi-ellipse caisson is a new type of structure ideally suited for open deep-water wharves with extensive application prospect. And it is made up of three parts, front and rear parts of the caisson are the semicircle sections, the middle part of the caisson is a rectangular section. Compared with conventional circular caissons, the quasi-ellipse caissons are a better choice for large-scale precast concrete caissons, because differential settlement of the foundation poses less of a risk to an upper wharf structure supported by one row of quasi-ellipse caissons in comparison with the two rows of circular caissons. The gravity dolphin wharf supported by the solid quasi-ellipse caissons was first used by the Dalian Ore Terminal Phaseâ…¡Project, it helped to lower the top elevation of the wharf significantly and provide better service functions, safety performance, and economic efficiency. At present, fewer studies have been made on hydrodynamic characteristics of the quasi-ellipse caisson, especially for the perforated quasi-ellipse caisson. Therefore, studying hydrodynamic characteristics of the quasi-ellipse caisson has very important practical meaning and popularization value.This paper presents the experiment investigation and numerical simulation of the wave forces on the solid quasi-ellipse caisson and the perforated quasi-ellipse caisson.Firstly, the experimental investigation of the regular wave forces and irregular wave forces on the solid multiple quasi-ellipse caissons and the perforated multiple quasi-ellipse caissons is conducted. The relation between the wave forces on the multiple quasi-ellipse caissons and the parameters such as relative interval, incident wave direction, relative wave height and so on is analyzed. In addition, the wave forces of the perforated multiple quasi-ellipse caissons are compared with that of the solid multiple quasi-ellipse caissons.Secondly, the frequency-domain numerical model of wave forces on a solid quasi-ellipse caisson is developed in the thesis. On the basis of the two-dimensional source representation method, the regular wave forces on the solid quasi-ellipse caisson are obtained. The wave force of the n-th component wave on the solid quasi-ellipse caisson is calculated based on two-dimensional source representation method, the random wave forces of different cumulative probability on the solid quasi-ellipse caisson are obtained by the method of spectrum analysis. Compared with the results of the analytical solutions and experiments, the frequency-domain numerical model proves to be correct and effective. The numerical model is used to investigate the relation between wave forces and the parameters such as incident wave direction, relative length-width ratio and so on.Finally, the three-dimensional numerical model of wave interaction with perforated quasi-ellipse caisson in time domain is established. The Navier-Stokes equations are solved by the finite difference method, and VOF is employed to trace the free surface. The boundary of the perforated quasi-ellipse caisson is treated by the partial cell method and good effect is obtained. Based on the Cnoidal wave theory, wave-maker is set; combining with the numerical sponge layer and SRC radiation condition achieve the damping elimination to the incident wave, the radical sign style of the attenuation quotient is chosen. The numerical model is verified and used to investigate the characteristics of flow field and wave surface around the perforated single quasi-ellipse caisson and the perforated multiple quasi-ellipse caissons, the wave forces on the perforated quasi-ellipse caisson is also carried out, and it is compared with that of the solid quasi-ellipse caisson.