Experimental Study of Central Bar Morpho-dynamics Under Penetrating Frame Groups

Various forms of penetrating frames have been developed and applied in the central bar protections of Yangtze River, China. However, the scour and deposition characteristics of central bars are always complicated and yet been totally understood. To properly evaluate the impacts of different penetrating frame forms, both twisted Double-H and Tetrahedron-like penetrating frame groups are selected to form fish-bone dikes which are frequently observed in the waterway regulation projects of Yangtze River. Flume experiments with different discharges (91L/s~176L/s) are thus conducted. Erosion around the head of the central bar is effectively prevented for both twisted Double-H and Tetrahedron-like penetrating frame groups. However, variations of the transverse shoal profiles differ between these two types of penetrating frames. The flow field is slightly altered in the presence of twisted Double-H penetrating frame groups, especially for low-speed cases. Overall, the Tetrahedron-like penetrating frame groups perform better as bar protection measures in the inland waterway engineering. The present study provides a guidance for geometrical design of penetrating frames and their practical applications.