基于中小河流弯道受损岸坡修复的楔形丁坝群水沙特性研究

Unlike traditional measures of stream bank protection, such as riprap concrete paving, or gabion walls,the stream barbs, which as a specialized ecological hydraulic structure for bank restoration in small and medium sized river bends, are drawing increasing attention with their unique ecological benefit. Currently, there is no report on related studies in domestic, however it have been carried out abroad widely. Hence, the function mechanism and design guidelines of stream barbs for bank stabilization need to be settled urgently. In this study, based on the flow and sediment dynamics problems induced by the layout of stream barbs against the flow direction in river bend, the three-dimension flow, sediment transport or bed deformation numerical model will be developed on the basis of the summary analysis on present achievements in bend hydraulics and spur dike hydraulics. Secondly, through verifications of flow and bed changes between laboratory flume experiment data and numerical simulation results with and without stream barbs, the effects of stream barbs in channel bend will be analyzed. And then, the study on different arrangements of barb groups will be carried out to determine the layout principle of stream barb installation. Finally, we will reveal the function mechanism of stream barbs in channel bend, and the general hydraulic design rules will also be suggested. In summary, the project we will study can contribute to the integration of stream barbs design and numerical simulation method, and the findings will provide technical support for design and construction of stream barbs in river bank restoration field.

楔形丁坝群作为一种专门用于中小河流弯道外岸岸坡修复的生态水工结构，相比抛石、混凝土铺装和石笼墙等传统护岸方式，以其特有的生态效益日益引起人们的重视，目前国外已开展相关研究，而国内还鲜见有相关研究报道。楔形丁坝群在弯道受损岸坡修复的作用机制和设计准则亟待解决。本项目针对弯道内楔形丁坝群逆水流方向布置所产生的水沙问题，基于对弯道水力学和丁坝水力学现有研究成果的总结分析，建立适用于该问题的三维数学模型；对比验证楔形丁坝群布置前后弯道内的水流与河床冲淤变化，解析弯道内楔形丁坝群的作用影响；通过对楔形丁坝群不同布置方式的研究，阐明影响弯道内导流和冲淤分布效果的结构物布置原则，最终揭示弯道内楔形丁坝群的水沙作用机制，并提出相应的水力设计准则。项目实施将有助于数值模拟手段与楔形丁坝群设计的融合，研究成果可为中小河流岸坡修复领域楔形丁坝群的设计和施工提供科技支撑。

蜿蜒曲折是河流动态演变过程中的一种自然倾向，天然河流大多维持弯曲的常态。楔形丁坝群作为一种弯道外岸岸坡修复的生态水工结构，以其特有的生态价值日益引起人们的重视，其作用机理和设计准则亟需补充和完善。本项目针对弯道三维水沙特性和楔形丁坝群的结构和布置特点，建立了适用于模拟弯道内结构物附近三维流场、冲淤变形的水动力数值模型。依托经典弯曲水槽试验的测量结果，验证了模型模拟弯道内三维水流和冲淤变形特性的能力，并模拟分析了楔形丁坝群布置前后对弯道内外岸侧近岸水流挑流和冲淤状况的影响。通过对楔形丁坝群布置角度、长度、高度和间距各参数影响分析，揭示弯道内楔形丁坝群的水沙作用机制，阐明影响弯道内导流和冲淤分布效果的结构物布置原则，最终提炼形成了弯道内楔形丁坝群结构设计步骤和方法。研究成果有助于数值模拟工具与楔形丁坝群设计的融合，可为河流岸坡修复中楔形丁坝群的工程设计和优化提供支持和指导。