舟山东港新城溃堤洪水演进数值模拟

台风会引起风暴增水和强浪。围填海工程建于软土地基上,海堤易产生不规则沉降,在台风引起的强浪作用下有可能发生溃堤,海水在高水位下大量涌入围区,引发灾难。针对溃坝的急变流特性,基于Delft3D Open Source,采用一种基于经典交错网格的改进型数值方法(其水流扩展流动数值近似算法符合动量守恒,而水流收缩流动数值近似则满足伯努利方程),建立了舟山东港新城溃堤洪水演进模型,并计算了最大可能风暴增水条件下溃堤洪水在东港新城的演进过程。结果表明,围区内的地形形势对洪水的演进及最终分布起了决定性作用,当溃口出现在不同位置时,影响范围和程度不一样。东港南部由于地势较低,且没有大型的吸纳洪水的人工湖,当附近出现50 m宽的溃口时,近乎整个南部区域都会受到海水的影响;而北部由于地势相对较高,影响有限。

Numerical simulation of sea dikes breaching flood in Donggangxincheng of Zhoushan

Typhoon can cause storm surge and strong waves. Since the reclamation projects are built on soft soil foundation, which may cause the seawall subsidence. In that case, disaster strikes when the strong waves cause sea dike breaching and seawater pours into the reclaimed area. An improved numerical method based on classic staggered grid was introduced in this study. In flow expansions, a numerical approximation was applied that was consistent with conservation of momentum, and in flow contractions, a numerical approximation was applied that was consistent with the Bernouilli Equation. The flood evolution model of Zhoushan Donggangxincheng was established, and the evolution process of the flood and breach under Probable Maximum Storm Surge was calculated. The results show that orographic terrain plays a decisive role in the evolution process and final distribution of the flood. The range and degree of influence differs when fissure occurred in different location. Almost the entire southern region of Donggang can be affected by a 50-metres-wide fissure nearby due to the low terrain and lacking of large-scale artificial lakes, while the influence in the northern area is limited due to the relatively high terrain.