【摘要】 海底条件的变化可能会加剧人工鱼礁的局部冲刷甚至产生掏空,导致人工鱼礁倾覆或掩埋,最终影响人工鱼礁的生态修复功能。为更好地了解人工鱼礁的冲刷特性,明确冲刷地形的形成机制,本研究首先采用物理模型试验的方法,对放置在粉砂底质上的人工鱼礁在不同水流条件下的局部冲刷问题进行了研究,并通过对原型流场进行数值模拟,讨论分析了水流及礁体结构特征对局部冲刷形态的影响机制。模型试验结果显示,0.11 m/s流速对试验选取的模型沙的影响不显著,礁体模型背面冲刷坑的深度仅为0.5 mm,两侧无明显冲刷坑,当流速增加到0.22和0.27 m/s时,沙床表面形成了均匀分布的沙鳞,背面冲刷坑深度分别达到1.0和1.5 mm,两侧冲刷坑的最大深度为4.5 mm,宽度分别为4.0和7.5 cm;流场数值模拟的分析结果显示,原型条件下流场、沙床剪切力和涡量的高值区和模型试验中冲刷强区存在对应关系,礁体的开孔和多柱支撑设计增大了局部冲刷强度。该研究表明,在粉砂底质条件下人工鱼礁的局部冲刷程度随流速的增加而增强,但总体冲刷不严重,未出现掏空或掩埋现象;礁体结构对局部冲刷有较大影响,因此,礁体设计与布局时应综合考虑流场效应、稳定性和冲刷形态等因素。更多还原

【Abstract】 Artificial reefs(ARs) are an important part of marine ranching, which are installed in seabed to protect and cultivate marine life systems. After ARs are deployed, changes in seabed conditions may intensify local scouring of seabed nearby ARs and influence the stability of ARs. Therefore, it is necessary to investigate the scouring characteristics. In this study, a physical model experiment was conducted in an experimental sink to investigate the local scouring of an artificial reef at different water flow velocities, which was placed on silty sand bed. The experiment results show that the scouring response of the silty bed to the 0.11 m/s flow velocity is not significant. The depth of the scouring hole behind the reef model is 0.5 mm, and there is no obvious scouring hole on both sides. When the flow velocity increases to 0.22 and 0.27 m/s, sand scales are uniformly distributed on the surface of sand bed. The depth of the scouring hole behind is 1.0 and 1.5 mm respectively. The maximum depth of the scouring holes on both sides is 4.5 mm and the width is 4.0 cm and 7.5 cm respectively. Combined with the experiment results, the numerical simulation method was introduced to analyse the mechanism of scouring phenomenon nearby ARs. According to the simulation, the flow field, shear force and vortex distribution are similar to the scouring pattern of silty sand bed in the experiments. The numerical simulation results show that the holes in the surface and multi-legs of reef increase the flow and scouring strength. The high value area of above three parameters corresponds to the area with stronger scouring. It is concluded that the scouring strength of ARs in the silty sand bed increases with flow velocity, but it is not strong enough to influence the stability of reef model. The structure of ARs does have effects on the local scouring. Flow field, stability and scouring pattern should be taken into consideration during the design of ARs.更多还原