| 摘要 |
PURPOSE:To prevent production of a re-reverse flow during exhaust of a compressed air, by a method wherein a reverse flow material in a hollow pipe is discharged by feeding a compressed air into the hollow pipe, and after a sand plug is formed to the lower part of the hollow pipe in a condition that the pipe is forced into a compressed air state, the compressed air is exhausted. CONSTITUTION:Sand is charged in a sand reservoir 4 formed at the upper part of a hollow pipe 1 by partitioning with a valve 3, a compressed air is fed in the hollow pipe 1 through a compressed air pipe 5 to drain water in the hollow pipe 1 from a lower end, and the interior of the sand reservoir 4 is foced into a compressed air state. A sand plug 6 is formed by dropping the sand in the sand reservoir 4 into the lower part of the hollow pipe 1 with the valve 3 opened in a condition in that the interior of the hollow pipe 1 is forced into a compressed air state. After the compressed air in the hollow pipe 1 is exhausted, the hollow pipe 1 is penetrated in a sea bottom group 7 down to a given depth as the sand is charged. Further, the compressed air is fed through the compressed air pipe 5, and as the sand in the hollow pipe 1 is discharged, the hollow pipe 1 is lifted up to build a sand pile. |
