【作者】 孙苗苗；

【导师】 赵林；

【作者基本信息】 中国海洋大学 ， 港口、海岸及近海工程， 2010， 硕士

【摘要】 在全球气候变暖导致的海平面上升和风暴潮灾害加剧的影响下,我国沿海地区若干堤防工程将面临防护标准不足的问题。一味加高海堤不仅需要巨大的建设和维护投资,而且使溃堤风险和损失加大,沿岸居民和其他土地使用者不安全感增加,海岸生态环境恶化。兴起于欧洲的允许部分越浪植物加固海堤背海边坡从而形成能抵抗部分越浪冲刷的多功能生态海滨防护体系,已在北海等沿岸国家得到推广,并被证明是符合可持续发展生态海岸要求的护岸方法。这一体系的重点在于允许部分越浪海堤的断面选择与设计。在工程设计中,传统上通过物理波浪水槽断面实验确定设计断面的越浪量,为海堤断面的优化设计提供依据。研究达到工程实用水平的数值波浪水池是国际海岸与近海工程界关注的热点,近年来得到迅速发展。本文基于FLUENT商业软件,在粘性流体的理论框架下,采用在动量方程中添加附加源项的方法,基于有限体积法,采用k-ε湍流模型,实现了适用于VOF方法的数值造波技术,通过计算,验证了数值波浪水槽造波的有效性,将此技术应用于越浪的数值模拟。本文在对以往相关研究成果进行回顾和分析后,在数值波浪水槽中对规则波在不可渗透简单斜坡堤上越浪过程进行了数值模拟,并越浪量计算结果同Holger Schuttrumpf (2002)物理实验结果及Holger Schuttrumpf (2002)理论公式进行比对。模拟结果表明：本数值模型能够较好地复演海堤越浪时爬坡,越过堤顶及背浪坡的过程,本数值模型的越浪量结果与试验结果的吻合较好,与理论公式结果同实验结果相对差值在同一个量级。许多研究表明,仅用平均越浪量来考虑越浪对背浪坡的破坏是不完全确切的。平均越浪量在背浪坡滑坡中起控制作用,但是无法描述背浪坡冲刷性破坏,需了解越浪水流在堤顶及背浪坡的流深、流速分布,估算海堤堤顶及背浪坡的侵蚀性和渗透性破坏。对本文第四章模拟的海堤越浪结果进行逐个分析,依据Holger Schuttrumpf理论公式,对海堤越浪水流在向浪坡,堤顶,背浪坡的流深、流速进行研究,结果表明,本数值模拟能较好的模拟波浪越浪后的各个过程,能有效模拟波浪在向浪坡爬高、流深、流速及越堤后在堤顶及背浪坡的水流流深、流速的问题。海堤的不同结构型式影响越浪流的流深、流速分布。在数值水槽内模拟了不同结构型式海堤的越浪过程。给出了不同海堤堤宽、不同海堤背浪坡坡度、不同海堤堤面粗糙程度对越浪流的影响。1)海堤堤顶宽度在3m-6m之间,增加堤顶宽度能使到达海堤堤顶与海堤背浪坡交界处越浪流的流深和流速减小。2)海堤背浪坡坡度1：m在1：2-1：4之间,增加m值能减小越浪流经过海堤背浪坡的流速。3)增大海堤堤顶及海堤背浪坡堤面的粗糙程度,能有效减小越堤水流流经海堤堤顶及海堤背浪坡的流速。更多还原

【Abstract】 Under the influence of sea levels rising by the global warming and storm surge disasters increasing, Chinese coastal areas will face a standard of protection embankment shortage. Simply heightening dikes will cause a series of disadvantage, such as a huge investment in construction and maintenance, bursts of r isks and losses to increase, coastal residents and other land users to increase the sense of insecurity, deterioration of coastal environment. Comcoast is a European project which develops and demonstrates innovative solutions for flood protection in coastal areas. Comcoast creates and applies new methodologies to evaluate flood zones from an economical and social point of view. A more gradual transition from sea to land creates benefits for a wider coastal community and environment whilst offering economically and socially sound options. The aim of ComCoast is to explore the spatial potentials defence strategies for current and future sites. The focus of comcoast is selecting cross-section of dike allowed overtopping。Traditionally, physical modeling approach is used to study overtopping of water waves over seawalls. Nowadays numericalwave tank(NWT) is a potential tool to study propagation,deformation and breaking of water waves with numerical experiments.Based on the N-S equation, the VOF method is used to track the free surface, the additive sources in the momentum equation are used to generate and absorb waves, the method of waves generating and absorbing i n the viscous fluid is presented. The numerica I wave flume which can both generate waves is obtained. The validity of waves generating is numerically confirmed.After review of the literature on the overtopping of dikes, regular wave overtopping over the crest of an impermeable coastal structure I ocated on a s I op i ng beach i s pred i cted numer i ca I I y by us i ng the numerical model developed previously for predicting wave run-up on such a structure located on the horizontal seabed. The computed average overtopping rates are shown to be in good agreement with available small-scale test data and the results calculated by the Holger Schuttrumpf (2002). Compared to the Holger Schuttrumpf theory equations, the present NWT can effectual ly solve the problems, which include the violent deformation, jet and breaking of the free surface.Although wave overtopping is explicitly considered in the design of dikes, only mean overtopping rates are included ae a desing parameter now. However, mean overtopping rates are neither appropriate for the description of the infiltration and erosion processes nor for the initiation of dike fanilures. The previously pibl ished results show that sometimes mean overtoppong rates are not always appropriate to describe the associated dike failures. Flow velocities and layer thickness of the water over the dike are required to assess the inflitration and erosion on the landward side of the dikes by overtopping water. Based on date of chapter 4, Compared to the Holger Schuttrumpf theory equations, the present NWT is capable of simulating the wave overtopping process after all, effectively simulating waves run-up, flow depth and velocity on the seadike slope, and effectively simulating flow depth and velocity on the crest dike and the landward dike. Distribution of overtopping flow depth, velocity is impacted by different structural type of the dike. The numerical wave flume is used to study the overtoppong precoss of different structural type of the dike. The overtopping flow is changed as the crest width, landword slope, friction of the dike are changed.1) when the crest width of dike is among 3m-6m, the overtopping layer thickness and velocity on the crest dike is increased with the increase of the crest width of dike.2) When the landward slope (1:m) i s 1:2-1:4, the overtopp i ng ve I oc i ty on the I andward slope of dike is increased with the increase of the value of m.3) The overtopp i ng velocity on the crest on the I andward slope of dike is reduced with the increase of bottom frittom.更多还原