拱坝表孔泄流下游消能防冲形式的试验研究

Experimental Study on Energy Dissipater in the Downstream for Crest Spillway of Arch Dam

针对中型拱坝下游消能防冲形式的选择问题,通过物理模型试验,对比分析了长护坦防护、水垫塘+二道坝和短护坦先冲后护3种布置形式下相应的水力学指标。试验结果表明:长护坦方案时,水垫塘内水流流态较差,底板和护岸易失稳破坏;水垫塘+二道坝方案时,水流流态和各项水力学指标满足要求,但造价较高;短护坦先冲后护方案时,冲坑位置及深度均在允许范围内,该方案的应用会受到拱坝下游地质条件的制约。依据短护坦先冲后护的试验成果,提出初步确定短护坦防护范围的方法。本工程下泄单宽流量较小,根据试验成果及类似工程经验,结合坝址地质和工程造价因素,推荐消能工布置方案为"短护坦先冲后护"方式。

To make a better choice about the energy dissipation forms for the arch dam downstream,the hydraulics indicators of three forms were compared. The test results showed that under the scheme of the long apron,the flow regime was poor,the baseplate and revetment were unstable. Meanwhile under the scheme of the water cushion pond and second dams,the flow regime and hydraulics indexes met the requirements,however,the hydraulic optimization of water cushion pond was complex and the cost of second dam was high. Under the scheme of the short apron,the position and depth of scouring pit were within the scope of the permit,but it could harm the security and stability of the arch dam for the geological conditions of factors. Based on the test results,the scope of the short apron can be determined preliminarily. Thus,combined with the test results,engineering experience,geological conditions and project cost,the first choice for scheme of downstream energy dissipation was short apron scheme.