Study On Hydraulic Characteristics Of Central Bar Before/after Being Protected

The project of the Three Gorges has stored water since the date of 2003.6. Because of intercepting plenty of sand,"clear water"discharge makes the lower river bed of the reservoir have a long distance and a long time scour and river regime adjustment. With the water level down, the problems of the stability and reinforcement of a part of dredged shoals and projects should be discussed. The navigation-obstructing condition of non-dredged shoals may get worse and new navigation-obstructing shoals may appear. The problems of obstruction to navigation will aggravate. These questions will affect the Yangtze River's channel directly. So it's very important to know the evolution features of the central bar and the stability and reinforcement of a project by studying the hydraulic characteristics of the central bar and the stability of the beach protection construction. This paper works for the hydraulic characteristics whether there is a central bar or not.This paper was carried out from the western communication construction project of the Research on the Key Techniques of Bar Projection in the Middle Reach of the Yangtze River, studies the flow structure near the central bar with a beach construction or not through the experiment of flume generalized model with three kinds of beach protection construction of the software platoon beach protection belt, the triangular pyramid permeable frame and the fish-bone dam. It analyses in detail the water level and velocity distribution characteristics whether there exists a beach protection construction of the central bar, focuses on the distribution regularity of the boundary shear stress along the lateral sideway and the whole survey area. It also studies in detail the pulsating kinetic energy and relative intensity of turbulence whether there is a beach protection. Compared with the water level, velocity variation and pulsating kinetic energy's distribution regularity of the three kinds of beach protection construction, it points out the triangular pyramid permeable frame protects the bar better and lowers the flow velocity. Not the software platoon beach protection belt but the fish-bone dam affects the whole survey area's flow structure distinctly. The fish-bone dam can't reach the expected effect of a beach protection because of the confusion of the flow pattern and the intensification of turbulence.