基于水槽模型试验的人工鱼礁局部冲淤研究

Study on local scour of artificial reef based on flume test

  • 摘要: 为提高人工鱼礁建设选址和礁体设计的科学性,基于试验水槽对2种人工鱼礁在粉砂黏土上的局部冲淤情况进行了物理模型试验,通过地形测量和理论分析,研究了5组不同流速条件下2种人工鱼礁礁体结构的局部冲淤情况。结果表明,在粉砂黏土底质上,流速小于0.22 m·s−1时,泥沙扰动小,2种礁体的周围局部冲刷小,冲淤形态以礁体底板附近浮沙堆积为主,且随速度增大而增高;流速大于0.22 m·s−1时,洗掘现象较为明显,鱼礁周围冲刷坑范围及深度随流速的增大而增加,而礁体周围泥沙堆积高度随速度增大而减小。支撑结构较为复杂的A礁冲淤现象显著且复杂,冲刷坑深度最大值位于礁体中间底部,为−15 mm,且在礁后1倍礁高处出现长尾状泥沙堆积,其在0.27 m·s−1流速时达到最大值5 mm;而B礁冲淤现象不显著,仅在底板附近出现少量堆积与冲刷坑,但由于底板开口比较大导致B礁发生沉降。因此今后的研究应结合建设选址海域的底质及水文特征对礁体支撑结构和底板进行优化设计并进行模型试验及数值模拟,以避免礁体冲淤严重引起沉降、掩埋等现象,从而影响鱼礁建设效果。

     

    Abstract: In order to improve the scientificity of artificial reef construction site selection and reef body design, we carried out the physical model tests of the local scour and deposition of two kinds of artificial reefs on silty clay based on experimental flume. Through the topographic survey and theoretical analysis, we investigated the local scour and deposition of five groups of different reef structures (two kinds) artificial fish reefs at different velocity. The results show that when the flow rate of silty clay was less than 0.22 m·s−1, the sediment disturbance and the local scour around the two reefs were small, and the main form of erosion and deposition was the accumulation of floating sand near the reef floor, which increased with the increase of velocity. When the flow velocity was greater than 0.22 m·s−1, the scour pattern was more obvious. The scour pit range and depth around the reef increased with the increase of flow velocity, while the sediment accumulation height around the reef decreased. The scour phenomenon of Reef A with complex supporting structure was significant and complex. The maximum scour pit depth was −15 mm at the bottom of the middle of the reef, and the long tail sediment accumulation occured at a height of 1 times of the reef behind the reef, which reached the maximum value of 5 mm at the flow rate of 0.27 m·s−1. However, the scour phenomenon of Reef B was not significant. Only a small amount of accumulation and scour pit appeared near the bottom plate, and its settlement was caused by the relatively large floor opening. Therefore, in the future research, the supporting structure and floor of the reef should be optimized and the model test and numerical simulation should be carried out in combination with the sediment and hydrological characteristics of the selected sea area for site construction, so as to avoid the phenomena of settlement, burial and bed surface hollowing of the reef.

     

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