| 摘要 |
PURPOSE:To prevent wasteful use of a drain material, by a method wherein the drain material, positioned along the outside wall of a mandrel is lowered in a condition in which the upper end side is nipped at the level of height about equal to a driving depth, and during lowering, the material is cut in a required driving length. CONSTITUTION:After a beltform drain material A is attached to a mandrel 12, the mandrel 12 is lowered by length about similar to depth H, by which it is driven into a soft ground (a), through driving of a leader 13. When the level of the height, equal to the driving length, of the upper end of the drain material A is lowered to a position within the reach of an operator on a working ship 10, lowering of the mandrel 12 is stopped, and thereafter, the drain material A is cut in a required length position to hold it between the nip formed by a nipping mechanism 15. The mandrel 12 is then lowered to drive it into the soft ground (a) to a required depth. |
