Theoretical Determination And Experimental Study On The Position Of Spur Dike In River Channel Regulation In Mountain Rivers

In the waterway regulation project,the frequently used measure is to build rectification buildings,and spur dikes are one of the most commonly used rectification buildings.However,the construction of the spur dike has changed the original terrain of the river,causing streamline concentration,resulting in changes in the local flow structure and triggering new river bed evolution.Therefore,it is necessary to study the location of the spur dike.This article relies on the “Research on the physical model test of the Xiaomitan Waterway of the Channel Regulation Project in the Upper Reach of the Yangtse River and the Yanqi River in the Upper Yangtze River” and collects relevant data comprehensively.Through theoretical analysis,prototype observation and dimensional analysis methods,the riverbed of the experimental river reaches The detailed study of the evolution law,the use of two-dimensional mathematical model flow test,physical model test and generalized tank test combined with the method,the scientific determination and verification of the theoretical determination of the spur dike position,based on this analysis Changes in the flow characteristics near the spur dikes in the remediation scheme.The main results of this research are as follows:(1)Under the three working conditions of spur dike and no spur dike,through the verification of the surface line and velocity of the flumes,the mesh size and parameters of the mathematical model were continuously modified,and the mathematical model of the flumes was successfully established.(2)Starting from the influence factors such as flow rate,length of dam and deflection angle of spur dike,the relationship between the width of spur dike 5° flow zone and their existence was analyzed quantitatively.The study found that there is a positive relationship between the width of the spur dike’s 5° flow zone and the length of the dam,and there is an inverse relationship with the flow,and there is no direct relationship with the deflection angle.In the condition of considering only the flow and the length of the spur dike,the theoretical formula of the spur dike position was fitted.(3)By means of theoretical analysis and prototype observation,the analysis of the deep-sag line,riverbed cross-section,and beach hazard of the research project reaches has been carried out,and the results of the recent stable evolution of the engineering river reach have been determined.(4)The accuracy of the mathematical model was confirmed by verifying the surface velocity and flow of the surface line and cross section of Xiaomitan natural channel.In order to better understand the hydraulic characteristics of the obstructed river,a recognizing test of the characteristics of water and sediment was carried out.Finally,it was concluded that the shallow section of the Jinzhongyu section was a dry shoal,while the Xiaomitan section was stranded during the dry season,during the flood season.The water flow is rushing.(5)Four kinds of remediation plans are proposed,including three design plans and one optimization plan.The position of the spur dike in the plan was determined by theoretical formula calculation.After a comprehensive analysis and comparison,it was found that the remediation effect of design plan No.3 was better than that of plan No.1 and plan No.2.In the optimization plan,the plan of shortening both the spur dike and the straight dam by 10 m was the most good.