| 摘要 |
PURPOSE:To make easier the lowering, moving, and pulling up of a fence by providing a float on the upper end edge and also a weight group and an expandible tube on the lower end edge of a fence. CONSTITUTION:In a fence 1, a float 8 is provided on the upper end edge, and a weight group 3 and an expandible tube 7 are provided on the lower end edge. When lowering the fence 1, the lower end 1a of the fence 1 easily goes down to the river bed 14 under the weight of the weight group 3 without causing buoyancy since the tube 7 is in the contracted state, and the fence 1 is laid in a tensed state between the river bed 14 and the float 8 provided at the upper end edge 1b and floating on the water surface. When moving the fence 1, compressed air is charged into the tube 7 to give buoyancy to the tube 7 and the fence 1 is moved by a tug boat, thereby relieving the gravity of the weight group 3. |
