| 摘要 |
PURPOSE:To pull up a casing by leaving a drain paper under the ground exactly by providing a projected part having a pressing face for the drain paper on its lower end to an elevating cylinder set on the lower part of the inside of the casing. CONSTITUTION:A drain paper 6 is inserted into the through hole 91 of a projected part 9, and the tip of the paper 6 is pulled out of a slit hole 51 on the lower end of a casing 5 and alternately folded sidewards. The casing 5 is driven to a given depth into the ground and then pulled up by as much distance as the stroke of an elevating cylinder 8. In this case, when the paper 6 is raised with the casing 5, the cylinder 8 is extended and the pressing face 92 of the projected part 9 is sent downwards with the paper 6. Since the pressing force of soil covering the tip end of the paper 6 outweighs the friction between the through hole 91 of the projected part 9 and the paper 6, the casing 5 alone can be drawn out by leaving the paper 6 in soil. |
