| 摘要 |
PURPOSE:To enable a V notch to be provided in a given position during fall- down, by a method wherein on and after the starting of fall-down of a flexible film weir from a rising attitude, a part of the surface of a river-bed, with which the surface of the downstream side of the weir is forced into contact, is formed in a level lower than that of the surface of other river-bed part. CONSTITUTION:A bagform body 20, being the body of a rubber weir 10, is secured to a river-bed 12 and slopes 14 of both river shores by means of a press metal 26, and the total surface of a river-bed, extending in the direction of a flow commencing with the press metal 26 and in a range of the length of 0.6H, wherein H is the depth of water, is formed in the same level. In a portion, located down the stream from said range, a concave part 16 with width W is formed about in a central position of the bagform body 20, and a surface 18 of other river-bed is formed in a flat manner flush with the surface of the river- bed extending in the range of the length of 0.6H. This, when the bagform body 20 is fallen down from a complete rising state, enables a rubber film 22 on the downstream side to start enterance into its interior in a position of the concave position 16, and causes a V notch to be provided in the upper part of the weir thanks to a water pressure. |
