新型管桩潜坝的局部冲刷研究

Study on local scour of the submerged pipe-pile dike

对丁坝局部冲刷问题研究现状进行了讨论,在此基础上,选择黄河上九堡弯段为典型河段,建立了动床变态概化河工模型,进行了新型管桩潜坝导流作用与局部冲刷的研究。本文对管桩潜坝的局部冲刷机理进行了分析,讨论了管桩潜坝在不同流量时的导流效果,以及坝头局部冲刷坑形成的初始、发展、稳定三个阶段;分析了来流流速、单宽流量、床沙组成、管桩疏密度、迎流角度等因素对管桩潜坝局部冲刷的影响。通过量纲分析,构建了包括局部冲刷主要影响因素的无量纲综合因子;根据模型试验与原型观测资料,通过拟合分析,建立了可供实际工程设计使用的新型管桩潜坝局部冲刷计算方法。

This paper discusses the current studies on local scour of spur dike and presents an experimental study of the channeling effect and local scour of a submerged pipe-pile dike on a distorted movable-bed generalized model for a typical reach located at the Jiubao bend of the Yellow River.We analyze the local scour mechanism and the channeling effect under different flow rates,and divide the formation of local scour pit into initial stage,developing stage and stable stage.The local scour depends various factors,such as flow velocity,unit width discharge,bed load composition,pipe pile spacing,incident flow angle of the dike,etc.The effects of these factors are analyzed.With consideration of the major factors,dimensionless integrated factors are derived through dimension analysis,and a calculation method for local scour estimation in practical pipe-pile dike design is put forward on the basis of model measurements,prototype observation data and data-fitting analysis.