溢洪道转弯出水渠体型及出口防冲措施优化研究

Research on the Type and Anti-scour Measurement Optimization of Curved Outlet Channel of Spillway

西洋河水库除险加固工程新建溢洪道通过出水渠转弯将下泄水流在京新高速前导入下游河床,转弯角度达54°。初设方案水工模型试验中弯道水流明显偏向左侧,渠内水流出现波状分界,两侧边墙出现回流,流态较差,导致出口水流扩散后左侧冲向高速桥墩,下游河床冲刷严重,无法满足消能防冲要求。采用FLOW-3D软件对出水渠体型优化方案进行了数值模拟,并进行了推荐方案的物理模型试验。研究成果表明:优化后的矩形断面平坡出水渠,水流束窄效果较好,渠内回流消失,流态明显改善。出水渠体型优化后渠内流速增大明显,因此针对下游防冲措施进行了不同方案对比,并推荐了可行方案。

In the reinforcement project of the Xiyanghe Reservoir, a newly built spillway will lead the discharge flow into the downstream riverbed before Jingxin Expressway through the curved section of the outlet channel, with a turning angle of 54°. In the hydraulic model test of initial design, it was found that the water flow in the canal is obviously inclined to the left and shows wavy boundary with backflow near the sidewall meaning that the flow pattern in outlet channel was poor, which cause the outflow to spread to the left side and scour the bridge pier of the expressway. The downstream riverbed was severely scoured, which could not meet the requirements of energy dissipation and scouring prevention. In order to solve the problem, FLOW-3D software was used to conduct numerical simulation of the optimization of the outlet channel shape and hydraulic model test was also conducted, so as to verify the feasibility of the optimization. The result shows that: using the rectangular section with flat slope outlet channel can narrow the water better than the initial design, which can also make the backflow disappear and improve flow pattern. The flow velocity in the outlet channel increased obviously after the optimization of outlet channel shape.Therefore, different schemes are compared for the downstream anti-scouring measures, and feasible schemes are recommended.