抗拖网海床基沙土基床冲刷机理及数值模拟研究

发布时间：2018-08-16 08:22

【摘要】：抗拖网海床基沙土基床冲刷是一个非常复杂的三维问题。抗拖网海床基是海底结构物的一种形式，目前国内外对海底结构物沙土基床冲刷机理已开展了一定研究，但要进行准确的分析预测需开展大量的工作。海底结构物冲刷的范围和深度是海床基结构设计中的重要参考依据。国内外学者对海洋结构物沙土冲刷做了大量原型观测、模型试验和数值模拟的研究工作，得出了很多有关计算冲刷深度的经验公式和半经验半理论公式，这对海床基沙土基床冲刷的研究具有很重要的意义。随着计算机硬件和CFD的发展，数值模拟以其独特的优势在未来海床基冲刷的研究中发挥极其重要的作用。本文采用FLUENT及FLOW-3D分别建立了抗拖网海床基的外部流场及沙土冲刷的三维数学模型，完成了外部流场和沙土基床冲刷的数值模拟。结果表明该数学模型能够模拟抗拖网海床基周围水流的流场形态和冲刷坑的变化情况。在模拟过程中，该数学模型形象直观地反映了抗拖网海床基周围的流场形态和漩涡体系，充分展现了冲刷坑的形成过程。此外，构成影响抗拖网海床基泥沙冲刷的因素主要有抗拖网海床基附近的水流条件和泥沙条件。本文通过改变水流流速和泥沙粒径，，来模拟不同条件下对沙土基床冲刷的影响，并分析了抗拖网海床基最大冲刷深度随这两种因素改变的趋势。结果表明，该模型可以预测抗拖网海床基沙土基床冲刷的范围和深度，具有一定的实用性，对海床基长期布放后的仪器姿态预测具有重要意义，同时对海床基的结构设计具有一定的指导作用。
[Abstract]:It is a very complicated three-dimensional problem to resist scour of sand-soil base bed based on trawl seabed. The anti-trawl seabed base is a form of seabed structure. At present, some researches have been carried out on the erosion mechanism of sand and soil base bed of seabed structure at home and abroad, but a great deal of work is needed to carry out accurate analysis and prediction. The scour range and depth of seabed structure is an important reference in the design of seabed-based structure. Scholars at home and abroad have made a large number of prototype observations, model tests and numerical simulation of sand erosion of marine structures. Many empirical and semi-empirical semi-theoretical formulas for calculating scour depth have been obtained. This is of great significance to the study of the erosion of the seabed-based sand-soil bed. With the development of computer hardware and CFD, numerical simulation plays an important role in the study of seabed erosion in the future with its unique advantages. In this paper, FLUENT and FLOW-3D are used to establish three dimensional mathematical models of the external current field and sand erosion resistance of trawler seabed, and the numerical simulation of external current field and sand bed scour is completed. The results show that the mathematical model can simulate the flow pattern and scour pits around the trawl bed. In the process of simulation, the mathematical model vividly reflects the shape of the current field and the swirl system around the trawl bed, and fully shows the formation process of the scour pit. In addition, the main factors affecting the resistance to sediment erosion are the current and sediment conditions near the trawl bed. By changing the flow velocity and sediment particle size, this paper simulates the effect of different conditions on the sand bed erosion, and analyzes the trend of the maximum scour depth of the trawl seabed with these two factors. The results show that the model can predict the range and depth of sand bed erosion resistance to trawling seabed, and has some practicability, which is of great significance to the prediction of instrument attitude after long-term placement of seabed base. At the same time, it can guide the structure design of seabed.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P754

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