大风江典型工程流场变化特征及悬浮泥沙扩散数值模拟

Numerical Simulation of Current Characteristics and Suspended Sediment Diffusion of Typical Engineering in the Dafengjiang River

关键词:  大风江  大桥建设  潮流  悬浮泥沙  数值模拟

Key words:  Dafengjiang River  bridge construction  tidal current  suspended sediment  numerical simulation

摘要:

悬浮泥沙扩散会导致局部海域悬浮物增加，对区域海洋生态环境造成一定影响。本研究以大风江大桥为例，基于MIKE21模型分析了大风江潮流场变化和悬浮泥沙扩散特征。结果表明，大风江以往复流为主，涨急时最大流速为0.80m/s，落急时最大流速为0.89m/s，落急流速(平均流速为0.42m/s)大于涨急流速(平均流速为0.28m/s)。大桥建设对大风江的流场影响有限，主要影响范围为桥的东北端海域。当悬浮泥沙在低潮释放时，落潮期间浓度10mg/L的包络面积(10.11km²)远大于涨潮期间的包络面积(1.10km²)。同时落潮时最远扩散距离为7.15km,涨潮时最远扩散距离为2.69km。悬浮泥沙的扩散会对周边海域的水质造成一定影响，因此建议控制施工规模并采取防污帘等措施来减少悬浮泥沙扩散。

Abstract:

The diffusion of suspended sediment will lead to the increase of suspended matter in local sea areas,which will have a certain impact on the regional marine ecological environment.Taking Dafengjiang Bridge as an example,this study analyzes the tidal current field change and suspended sediment diffusion characteristics based on MIKE21 model.The results show that the Dafengjiang River is dominated by reciprocating flow.The maximum flow velocity is 0.8 m/s in flood peak and 0.89 m/s in ebb peak.The ebb velocity (the average flow velocity is 0.42 m/s) is greater than the flood velocity (the average flow velocity is 0.28 m/s).The influence of bridge construction on the flow field of Dafengjiang River is limited,and the main influence area is the northeast end of the bridge.When suspended sediment is released at the low ebb,the envelope area of 10 mg/L during the ebb tide (10.11 km²) is much larger than that in the flood tide (1.1 km²).At the same time,the farthest diffusion distance is 7.15 km during the ebb tide and 2.69 km during the flood tide.The diffusion of suspended sediment will have a certain impact on the water quality of the surrounding sea area.Therefore,it is suggested to control the construction scale and take measures such as anti-fouling curtains to reduce the diffusion of suspended sediment.