Research On Flow Characteristics Of Spur Dike In Curved River

Spur dike is one of the most widely used hydraulic structures in river regulation engineering,which is often used in flood control engineering,bank protection and beach dissipation,curved river regulation and river ecological environment restoration engineering.Especially for the curved river,the setting of spur dike can make the main stream deviate from the embankment,control the river regime and protect the embankment from scouring.However,how to lay a spur dike on the bend is not clearly mentioned in the current design guidelines.In the related research literatures,the research contents are mainly the research of flow pattern of spur dike with fixed curvature,less considering the influence of curvature on flow pattern of spur dike.Therefore,it is of great theoretical and practical significance to make clear the flow characteristics of spur dike in different curvature curved rivers and provide necessary and reliable scientific basis for arranging spur dike in curved river.Based on the numerical calculation and simulation method,a three-dimensional rectangular Spur dike curve numerical model is established by induction of the characteristics of the actual river section.On this basis,the influence of two factors,the length of Spur dike(i.e.the width shrinkage rate of the river)and the radius of curvature of the curve on the water level of the curved section,the cross-section ratio drop,the reflux area,the flow velocity of the section,the turbulence characteristics and other water flow characteristics are studied.The main research content and results are as follows:(1)A numerical calculation model of the 180° curved channel is established by induction of the actual river section characteristics to cover the central angle of all curves.The turbulence model and VOF free liquid surface tracking method are used to study the flow characteristics of Spur dike on the bent channel,and the experimental results of the literature Spur dike are verified.The verification results show that the experimental numerical model and its method are relatively scientific and reasonable,and the content of this paper can be completed.(2)The flow characteristics of different river widths and narrowing rates are studied.The research shows that the maximum water level difference on the convex and concave bank,the maximum transverse ratio precipitation and the height of the dam head all increase with the increase of the narrowing rate of the river width.The water level near the dam head gradually decreases with the increase of the width and narrowing rate of the river,and the horizontal ratio of the dam axis increases with the increase of the width and narrowing rate of the river.When the width shrinkage rate of the river is small(0.1,0.15,0.2),the relative length of the reflux area and the width of the relative reflux area increase with the shrinkage rate of the river width.The width value of the relative reflux region is basically around 1.1.The range protected by50%,30% and 15% of the background flow rate after the wall of the dam basically increases first and then decreases and then increases.At the end of the dam,it is characterized by lower incision flow.The range,value and intensity of turbulent energy increase with the increase of the narrowing rate of the river,and the range basically coincides with the reflux area.(3)The flow characteristics under different relative curvatures are studied.The research shows that the water level difference and transverse ratio drop of the convex and concave bank show a tendency to increase first and then decrease with the increase of relative curvature.The drop difference between the axis of the Spur dike dam axis increases with the increase of the relative curvature.The length of the relative reflux area increases with the increase of relative curvature.The range protected by 50%,30% and 15% of the background flow rate decreases with the increase of relative curvature with the increase of the relative curvature,and then decreases and increase.The central angle of the curve corresponding to the position of the maximum turbulent energy and the maximum turbulence intensity gradually decreases with the increase of relative curvature.