施工分期导流围堰冲刷的清水动床模型设计
Clear Water and Moving Bed Model Design on Cofferdam Scour during Multi-Stage Diversion
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摘要: 施工导流是水利水电工程建设中的重要环节。由于它本身的特点及试验任务的要求,导流模型设计与其他河工或单项泄水建筑物模型相比有其特殊性。一般情况下,水利枢纽施工导流模型应设计成满足重力相似条件和阻力相似条件的正态几何相似模型。但考虑围堰头部局部冲刷时,模型沙的相似比尺和粒径选择则是关键问题。在介绍分析模型相似理论的基础上,得出围堰头部附近最大近底流速的计算公式,并以此作为泥沙的起动流速计算公式,证实它满足泥沙运动相似;利用常用的局部冲刷计算公式,考虑模型的正态特点,得到模型沙相似比尺和几何比尺的关系,给出了模型沙的选择原则。结论为类似工程设计与模型设计提供了重要的指导作用。Abstract: Construction diversion is an important part of hydropower engineering. Due to the Characteristics of itself and command of model test,diversion model design have the particularity compared with other river project and individual sluice structure model. In general,diversion model should be designed as normal and scale model that meet the requriment of Gravity similarity and Resistance similarity. Give consideration to local scour of cofferdam,selection of similarity scale and grain size of model sand is a key point.On base of introducing the principal theory of model similarity,thesis deduct the calculation formula of maximum bottom velocity,and think it as incipient velocity of sand,approve it meet the requirement of sediment movement;use the common calculation formula of local scour with consideration of characteristics of normal model,deduct the relationship between similarity scale of model sand and geometric scale,and provide the principal of model sand selection. Conclusion can provide the direction of the engineering designing and model designing.