Study On The Stability Of Central Bar Protection Structures

The waterway of middle reaches of Yangtze River has not been renovated systematically. To a large extent, it still keeps in a natural state and the navigation capacity is too poor. With the impact from natural conditions, the phenomenons, such as "low-resistance route", "flood prohibited" happen from time to time, which bring many uncertainty factors to the Yangtze River navigation. In order to prevent central bar body from eroding so as to beam water to the channel effectively and stabilize the low-flow channel, the central bar protection stucture are adopted to protect bar body, which is one of the principal means used in Yangtze River navigation channel Regulation Project at present. However, in the view of navigation channel regulation having been implemented, the phenomenon of central bar protection stucture being destroyed by water is too seriously, especially after the Three Gorges Project reservoir, which makes the conditions of water and sediment of the middle and lower reaches of the Yangtze River change greatly ,thus a long time ,long-distance scour deformation will happen, the impact on waterway as a result of the changing of a variety of beach body will be even more complicated, and the stability of central bar protection stucture will call for a higher technical requirements.In this paper, for the central bar protection stucture being widely adopted in the middle reaches of the Yangtze River Waterway Regulation Project, the failure mechanism of the central bar protection stucture is studied in detail by means of field research, theoretical analysis and overview of model test tank and so on, thus indentify the main effect of the stability of the central bar protection stucture . In this process, the Department of Concrete block scheduling software, tetrahedral water frameworks and fish bone dam are chosen separately as a simulated beach buildings. Through fixed-bed experiments, hydraulic characteristics near beach body under or not under the protection of beach buildings, such as the water level, velocity, and flow turbulence intensity are studied. From the velocity distribution chart and the flow turbulence intensity distribution which analyze the law of velocity distribution and flow turbulence intensity distribution around the beach body under different conditions, the result of the external flow conditions causing beach erosion and the damage of central bar protection stucture are received. Through water erosion test, the erosion and deposition characteristics of beach trough under the protection of different guarding beach buildings are studied in detail. Through the analysis and study of water damage features and the damaging factors of different central bar protection stucture, the relations between the process and degree of the damaging of guarding beach buildings and hydraulic elements and beach morphology are also clearly found. At the same time, the stability of different central bar protection stucture is checked.