Study On Influence Range Of Water Spur Dike In Typical Shoal Of Upper Reaches Of Yangtze River

Channel regulation is the main method of investment saving and quick effect that improves the level of inland waterway and improves the conditions of navigation.The spur dike is the most common remediation building in the shoal.At present,there are many researches on the influence areas of the high water level upstream and the areas of the backwater range downstream,mainly in plane area.However,the vertical magnitude of water level,flow rate and other effects on the spur dikes have not been well studied.Therefore,it is of great significance to carry out the study of the magnitude of the impact of the water spur dike in the vertical direction.In this paper,a two-dimensional flow mathematical model and a generalized flume experiment are conducted.The influence range of spur dikes in different types of typical shoal regulation is studied.Based on the analysis and experiment of the flow characteristics around spur dike,the influence of the geometrical size of spur dike on the flow amplitude is studied.The main results and conclusions are as follows.(1)As for the spur dikes with sink to limit water,the maximum value of the dikes influence on the velocity change rate ?,and the flow rate will change with the size of spur dikes.It does not necessarily appear that the spur dike just floods the corresponding flow.That is Rectify flow.There may be a greater flow level.The maximum velocity of flow rate a is mainly on the dam,the water depth is higher than 0-2m,and the flow rate is Q=(50,100)L/s.(2)With the increase of tank flow rate,the decrease of the contraction section and the decrease of flow rate ?,the maximum influence area is about 0-100 cm downstream of the dikes.The maximum flow rate of ? and the corresponding flow have no obvious correlation with dam length.While the ? maximum value corresponding to a positive flow and dam.When the height of dam(h) is sure,the largest impact flow basically fixed.The maximum influence line is defined.The flow rate become greater,the maximum influence line will move downstream.The geometrical size of spur dike has no obvious influence on the maximum influence line.Through single factor analysis on the attenuation of the flow Qbm and the height of dam h and dam length b results by fitting empirical formula is established in Rectangle Flume beam of water dike semi attenuation flow Qbm and the geometry of the dikes.The verification is in good agreement.(3)The actual control of three typical shoal single factor and dam crest elevation long studied the influence of amplitude of flow Q and analyzed the control of single factor H and length of dam crest elevation effect of B on the amplitude of Q traffic.The maximum influence flow and maximum influence ultra high range are determined.The relationship between flow rate change rate a and incoming flow is obtained.The relationship between the maximum speed change rate Amax and the height and length of spur dikes is obtained.Empirical relation between the magnitude of flow affected by spur dikes and the geometrical size and inflow conditions of spur dikes is also obtained.The validation results are basically satisfactory.(4)The numerical simulation of flow field for straight bend,bend and channel shoal is carried out respectively.Comprehensive upper shore indicators indicate that ships can sail from their own beaches.According to the empirical formula,the magnitude of the influence flow is calculated.Analysis of the causes of actual beach risks.The geometrical dimensions of spur dikes are recommended.