Experimental Study On The Hydraulic Characteristics Of A River Channel Under Ice Cap With Multiple Sections

For the rivers with flood disaster,even in the case of small flow,floodplain flow may be formed,especially once ice jam and ice dam are formed in the river,the main channel and floodplain will be blocked at the same time,dramatically reducing the cross section area of water,leading to dam overflow accident.Therefore,it is not only of great theoretical significance,but also of extensive practical application value to clarify the flow capacity and hydraulic characteristics of rivers with multiple sections under different ice conditions.In this paper,based on ADV and PIV velocimetry techniques,the following research work is carried out in view of the theory and application of velocity distribution and detection method of multiple cross-section channels under the ice sheet:(1)PIV and ADV were used to measure the velocity distribution of the channel in the complex section under the ice sheet,and the distribution characteristics of the velocity in the complex section under the ice sheet were analyzed from the transverse and longitudinal velocities,and the problems and errors in the velocity measurement were analyzed.(2)Three conditions of floodplain water level and six conditions of ice sheet and open current were designed for comparison test.Contrastive analysis of the resistance coefficient of several working conditions.A calibration method for the roughness of experimental platform using Xie CAI formula is presented.(3)according to the basic assumptions of ice under the water flow and NS basic equation,based on the quasi two dimensional model of kai-lin Yang,ice is deduced under the compound section of constant non-uniform flow depth of quasi two-dimensional model of transverse distribution of mean velocity and don’t have to be simultaneous to solve the complex equations of ice cover and bed shear stress calculation formula,gave a fast calculation method of flow capacity,find under the ice cap compound section canals transverse distributions of mean velocity of flow,and then through the model experiment to verify the compound section under the ice cap overbank transverse distribution of mean velocity of flow along the water depth of the rationality of the quasi two dimensional model.(4)Based on the hypothesis of Liu Peiqing and Planck’s characteristic length,the expression of kinetic energy loss and the calculation formula of lateral kinetic energy correction coefficient and kinetic energy loss rate of multiple cross-sectional channels under ice sheet are derived.The causes of apparent shear stress in momentum transverse transport are analyzed.(5)The velocity distribution law of the multi-section channel under the ice sheet is analyzed.The parameter sensitivity and value of velocity distribution formula under ice sheet are analyzed.