【作者】 任效忠；

【导师】 王永学；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2011， 博士

【摘要】 为适应船舶大型化、降低投资成本以及缩短工期的需要,当前深水港口建设常选在天然水深条件好或稍经疏浚的离岸深水区域且为开敞式码头。准椭圆沉箱是一种有广阔应用前景的新型深水开敞式码头结构型式,其水平断面由前后两个半圆和中间矩形三部分构成。相比传统的圆沉箱,准椭圆沉箱适合预制巨型沉箱。码头上部结构安置于一排准椭圆沉箱基础上,能有效避免采用两排圆沉箱导致的基床不均匀沉降问题。不开孔准椭圆沉箱首次应用于大连港矿石码头二期工程,有效地降低了码头面高程,实现了较好的使用性能、安全性能与经济效益。目前,关于准椭圆沉箱新结构的水动力特性研究工作还很少,尤其是开孔准椭圆沉箱。因此,开展准椭圆沉箱的水动力特性研究具有重要的实际意义和推广应用价值。本文应用物理模型试验和数值模型计算相结合的手段,对不开孔准椭圆沉箱和开孔准椭圆沉箱的波浪力进行了系统地研究。首先,本文开展了规则波和不规则波作用下不开孔与开孔准椭圆沉箱群墩波浪力的试验研究,分析了相对间距、入射波向、相对波高等因素对不开孔与开孔准椭圆沉箱群墩波浪力的影响；并对不开孔与开孔准椭圆沉箱群墩波浪力进行了比较。其次,本文建立了计算不开孔准椭圆沉箱单墩波浪力的频域数值计算模型。应用二维源分布法对不开孔准椭圆沉箱单墩规则波波浪力进行了数值模拟。基于二维源分布法得到不规则波浪的各个组成波作用于结构上的波浪力分量,应用波谱分析方法给出不同累积概率下作用于结构上的不规则波波浪力。计算结果与解析解、试验结果的比较验证,显示了该频域计算模型的正确性和有效性。应用该频域模型研究了入射波向、相对长宽比等因素与不开孔准椭圆沉箱单墩波浪力之间的关系。最后,本文建立了波浪与开孔准椭圆沉箱相互作用的三维时域数值计算模型。应用有限差分方法直接求解三维N-S方程,采用VOF方法跟踪流体自由表面。引入部分单元体方法处理开孔准椭圆沉箱边界并取得良好效果。基于椭余波理论,设置了规则波数值造波边界；采用海绵层阻尼消波和Sommerfeld辐射条件相结合的方法解决水槽末端的波浪反射问题,海绵层内的衰减系数选取为根号形式。时域数值模型的有效性进行了验证,应用该时域模型研究了开孔准椭圆沉箱单墩与群墩周围的流场与波面特征,开孔准椭圆沉箱波浪力也进行了数值研究并与不开孔准椭圆沉箱波浪力进行了比较。更多还原

【Abstract】 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 PhaseⅡProject, 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.更多还原