袁河新泉乡段梯级溢流堰水动力模拟及侵蚀分析

为了分析梯级溢流堰对袁河新泉乡段河道行洪及河床抗冲的影响,优化河道治理工程中溢流堰布置,建立了将拦河溢流堰作为闭边界条件的二维水动力数值模型,采用非结构化网格的有限体积法,对比分析了十年一遇洪水情况下梯级溢流堰建设前后河道水动力、河道水位、流场沿程变化特征,讨论了溢流堰布置对河道防洪及冲刷的影响。结果表明,在十年一遇洪水情况下溢流堰会抬升河道水位,平均增加0.49 m,满足河道行洪要求;梯级溢流堰使河道整体形成人工“阶梯深潭”体系,河道流速在空间上发生明显的异质性,堰上流速下降幅度较堰下流速大;水流发生急流与缓流之间交替,水流紊动强烈,加剧了水流能量损失,有效降低流速,减轻了河道冲刷,有利于稳定河岸结构。

Hydrodynamic Simulation and Erosion Impact Analysis for Xinquan Township Section of Yuanhe River under the Cascade Connection by Weirs

In order to analyze the effects of cascade overflow weirs on river flooding and river bed erosion of the Xinquan section of the Yuanhe River,and also optimize the layout of weirs in the river regulation project,a two-dimensional hydrodynamic numerical model is established by adopting the finite volume method and taking these overflow weirs as the closed boundary condition.The river hydrodynamics,river water level and flow field before and after the construction of the cascade overflow weirs under the 10-year flood are compared and analyzed,and the influences of overflow weir layout on river flooding and erosion are also discussed.The results indicate that,(a)the overflow weirs will raise the water level of river channel with an average increase of 0.49 m under the 10-year flood,which meets the flood discharge requirements of the river;(b)the arrangement of the cascade overflow weirs forms an artificial“step-pool”system,which makes the river flow velocity produces significant spatial heterogeneity,and the velocity decrease upstream the weir larger than that downstream the weir;and(c)the water flow alternates between the rapid and slow currents,and the water flow is turbulent,which consumes the energy of water flow,decreases the flow velocity effectively,reduces river erosion,and conducive to stabilize the river bank structure.