北江丁坝群水动力特性数值模拟及其对通航安全的影响研究

Numerical Simulation of Hydrodynamic Characteristics of Spur Dikes in Beijiang River and Its Influence on Navigation Safety

为了深入探究北江丁坝群对通航安全的影响,研究采用非结构化网格有限体积法计算模型(Finite Volume Coastal Ocean Model,FVCOM),以英德段23 km的北江干流河段为研究区域,构建了三维水动力模型,并通过实测数据验证了模型的有效性。基于此,预设了当恒定来流量为420 m^(3)/s情况下,模拟了有、无丁坝2种不同情境下的水动力特性,重点关注和分析研究区域的急弯段。计算结果表明,丁坝使得近岸水流流速降低了44.6%~90.3%,航道水深增大了0~0.2 m,主流流速增大了66.6%~121.8%。此外,丁坝集中了横向主流,游摆程度最大降低了41.6%,摆幅最大降低了50.2%,对提高航道通航能力起到了正面效应。然而,丁坝的布置也增加了一些负面效应的风险,如单侧长丁坝导致对岸近岸流速增大了73.3%~129.0%,航道水平主流线曲折程度由784.2 m降低到774.5 m,水流动力轴线弯曲半径减小了14.0%~36.7%,对通航安全存在一定的风险。成果不仅揭示了丁坝在特定河段水动力特性中的复杂作用,也为天然航道中丁坝对通航安全的分析提供了重要的参考依据。

In order to deeply explore the influence of spur dikes in Beijiang River on navigation safety,this study adopted the calculation model of unstructured-grid finite volume coastal Dcean model(FVCOM),took the mainstream reach of 23 km of Beijiang River in Yingde section as the research area,constructed a three-dimensional hydrodynamic model,and verified the effectiveness of the model through measured data.On this basis,the hydrodynamic characteristics with and without spur dikes were simulated under the assumed constant inlet flow rate of 420 m³/s,and the abrupt bend section in the study area was analyzed.The calculation results show that the spur dike reduces the near-shore flow velocity by 44.6%~90.3%,increases the channel depth by 0~0.2 m,and elevates the mainstream flow velocity by 66.6%~121.8%.In addition,the spur dike converges the lateral mainstream.The degree of swing is reduced by up to 41.6%,and the amplitude of swing is reduced by up to 50.2%,which has a positive effect on the improvement of the navigability of the channel.However,the arrangement of the spur dike also increases some negative effects.For example,the unilateral long spur dikes lead to the increase of the opposite near-shore flow velocity by 73.3%~129.0%,the decrease of the horizontal mainstream curvature of the channel from 784.2 m to 774.5 m,and the decrease of the bending radius of the hydrodynamic axis by 14.0%~36.7%,which may constitute a potential threat to the navigation safety.The results of this study not only reveal the complex role of spur dikes in the hydrodynamic characteristics of a specific river section but also provide an important reference for the analysis of spur dikes on navigation safety in natural channels.