Experimental study on mechanism and control of bank collapse

The paper analyzed the mechanism of different types of bank collapse, and made a comparison of the bank collapse protection with soft sanding bags and with stone by model tests. The test results are as follows: 1under continuous scour by water flows, the banks without any protection measures collapse in four forms: Strip-shape collapse at straight reaches, socket-shape collapse at bend reaches, collapse due to water level fluctuation, and collapse due to erosion of storm current and rainwater. (2)The banks with riprapping stones do not collapse in short time but will collapse finally, and the areas of banks collapse are enlarged gradually if stones are unevenly riprapped. (3)Water can filter through soft sanding bags while sands can not filter through them. The soft sanding bags can effectively protect the whole bank and prevent the local bank from collapsing and piping. (4)The edge of soft sanding bags can reach main river channel, and make main flows far away from bank. The areas of slack water form at bank sides and promote deposition. The test results indicated that the effect of bank protection with soft sanding bags is better than that with random riprap, and their investment are almost equal.