The Research Into Scour Mechanism Of Upper And Lower Double Spur Dike Along River In Mountain

Water conservancy project in the spur dike is one of the main building of river regulation, can shorten the water cross section width, accelerate the flow of riverbed scouring and broaden the navigable water depth, can reduce the Banks of the river flow velocity at the same time, reduce the nearshore currents energy to avoid the Banks suffer from excessive scour damage, to achieve the goal of maintaining the bank slope stability. In order to achieve line regulation effect, the effective control of river regulation and slow down the spur dike water destruction, most of the time, arrangement of mountainous rivers is upper and lower double spur dike or series spur dikes. More than in the past the study of spur dike is given priority to with single spur dike, therefore, the water destruction mechanism of upper and lower double spur dike problem is essential subject to be solved at present.This paper by the ministry of science and technology project "the upper Yangtze river waterway regulation mechanism and prevention of buildings water destruction monitoring technology" as the backing. The water destruction mechanism of double spur dike structure, double flow near the spur dike dam and two head of scour holes depth are described. This paper combined with the previous scholars on the research of the single spur dike hydraulic characteristics, through the Yangtze river upstream of existing typical pairs of spur dike water destruction data has devised two long dam than, 2 pick Angle form and the distance between three kinds of dam and three kinds of flow conditions, through the permutation and combination of 22 set conditions for water dynamic test bed, through the optimization analysis to choose the most practical and best control effect experiment scheme.A flume generalized model experiment and theoretical analysis of the experiment results, this paper discusses the various working condition when the upper and lower double spur dike process damaged by flood and water destruction volume. Made different dam length ratio and distance between dam and different traffic situations, erosion and deposition of the last balance contour map. Respectively in the form of spur dike on record with the head of scour hole is derived process, can be clearly observed from the figure the changing rule of the length and width of the hole with time. To get the test results are compared with previous experimental results of the single spur dike, analysis between upper and lower double spur dike, the cover of the effect. Because after construction of spur dike in mountainous rivers, spur dike, great changes have taken place near the sediment-carrying capacity of flow will be so this article also influence on upper and lower double spur dike on the sediment-carrying capacity makes a brief analysis.Spur dike water destruction mainly jetty head of water destruction and jetty head water destruction is mainly due to the scouring pit in jetty head, so from the theory to explore jetty head formula of the pit is necessary. Using dimensional analysis and least squares multiple linear regression analysis of experimental data, respectively is suitable for the mountainous rivers are scattered on rubble-mound spur dike is deduced and the calculation formula of scour hole depth along, sum up upper and lower double spur dike both the interaction relationship between scour depth, as to provide theoretical basis for engineering practice.