Study On Sediment Movement And Scouring Deformation Scouring Deformation Of Central Bar Before/after Being Protected

The water sediment monment regularity of the middle reach of the central bar of Yangtze River are verycomplex,especially the navigation problems are prominent,which have become the"bottle-neck"of restring the development of navigation.The beach protection construction can be used to protect the central bar in the aim of changing the situation, recovering and improving the channel conditions.So studying the sediment moment redularities and the scouring deformation characteristics of the central bar portected by a beach protection construction or not,has an important theoretiacl meaning and practical value.This paper was carried out from the western communication construction project of the research on the key techniques in the protection of the central bar projection in the middle reach of the Yangtze river. Based on the analysis of the evolution of the typical reach of the central bar,the experiment of the flume generalized model was carried on,relied on the Sanba beach of Shashi.And the sedimoent moment regularity and scouring deformation characteristics are studied systemtically when the central bar is unprotected and protected by the software platoon beach protection belt, triargular pyramid permeable frame and the fish-bone dam project.Through the theoretical analysis and model experiment, the central bar and riverbed scouring deformation regularity are discussed in detail with the central bar protected or not; it is given that the reguarity of streamwise variation of the sediment-carrying capacity of flow and the movable bed resistance on the bar and the braided reach,and the result of comparing with the sediment-carrying capacity of flow and the movable bed resistance is analyzed.The software platoon beach protection belt and the triargular pyramid permeable frame will enlarge the roughness of the central bar by calculating the beach face roughness of the central bar protected and unprotected.This paper points out the advantages and the disadvantages of the three kinds of construction, the software platoon beach protection belt,the triargular pyramid permeable frame and the fish-bone dam project, used at the central bar which are analyzed as a whole.The resluts of this paper could be appolied not only to the channel improvement project directly on the middle and lower course of Yangtze River,but also to those of other rivers.Meanwhile,they can enrich the content of channel improvement subject.