| 摘要 |
PURPOSE:To prevent the breakage of the film of a flexible dam by providing a buffer material to a floor portion where the film of the dam is attached in the flow direction of water and also to a floor portion within a range that the film on the downstream side is placed from the downstream side fitting position of the film when the film shrunk. CONSTITUTION:Buffer materials 3 and 3' are provded to the floor portion 2 between film-fitting portions 7 and 8 in the flow direction of water and also to the floor portion within a range that the film on the downstream side is placed from the downstream side fitting position of the film, and no buffer material is provided inside the film. Thus, even when the film 1 shrunk where a water level is preset downstream of the dam, no resistance to the flow of water occurs although the film of the downstream side fitting portion 8 is bent, no move occurs near and at the tip 9 of the folded portion of the film, and therefore, no abrasive damage to the film of the dam takes place. |
