黄河下游丁坝群对河势控制效果研究

Study of effects of spur-dike group on river-regime control in lower reaches of the Yellow River

下游游荡型河道的河势控制是黄河流域生态保护与高质量发展的重要内容.利用MIKE21软件构建黄河下游天然河道二维水动力数值模型,并用控制变量法,对比分析不同挑角、布设排数以及结构形式下丁坝群对河势的控制效果.结果表明,在黄河下游河湾段透水丁坝群的缓流落淤效果与实体丁坝群接近.实体丁坝坝后悬沙浓度从约30 kg/m^(3)下降到最低24.72 kg/m^(3),透水丁坝则下降至24.08 kg/m^(3);两者对河段凹岸流速减小平均贡献率均高达80%以上,具有很强的护岸效果.此外透水丁坝因其独具的透水性能,有利于水生生物繁衍生息,兼顾了防洪安全和生态友好.但因目前建造透水丁坝的配套理论与技术标准有所欠缺,工程中存在溃坝风险,因而需要进一步加强设计方法和工程新材料的研发.

To control the river-regime in the wandering channels in the lower reaches is important for the ecological protection and high-quality development in the Yellow River Basin.The 2-D hydrodynamic numerical model for natural channel in the lower reaches of the Yellow River is constructed using MIKE21 software,and the control effects of the spur-dike group on the river-regime at various oriented angles,rows and structures are analyzed by control variable method.The results show that the capacities of the permeable spur-dike group and solid spur-dike group are approximately same to slowdown the flow and deposit the soil in the bent segment of the lower reaches of the Yellow River.The concentration of the suspended sediment behind the solid spur-dikes decreases from about 30 kg/m^(3) to the lowest 24.72 kg/m^(3),while that behind the permeable spur-dikes decreases to 24.08 kg/m^(3).Both types of spur-dikes strongly protect the bank for the dikes may decrease the flow velocities by more than 80%.Besides flood control,the permeable spur-dikes,in which aquatic organisms are easily to live and reproduce because of its porousness,also have worthy ecological benefits.Nevertheless,the risk of dam break still exists in the engineering application due to lack of supporting theory and technical standard to construct the permeable spur-dikes.Hence,innovative design methods and new engineering materials are anticipated to improve the safety and practicability of control work.