| 摘要 |
PROBLEM TO BE SOLVED: To provide a compaction method which is high in protrusion restraining effects.SOLUTION: A ground improvement material is press-fit via an injection pipe into the ground so that an improvement body whose peripheral ground is compacted can be established in the ground, and the injection pipe penetrated into the ground is made to go up and down so that ground protrusions can be restrained. For example, the up-down process is executed posterior to the press-fit process. In the up-down process, the injection pipe is made to go up and down such that the established improvement body is thrust, and at that time, the injection pipe is made to move forward and backward in a depth section almost for one step. The injection pipe may be made to go up and down while being rotated. Since depression occurs in the peripheral ground according as the injection pipe is made to go up and down, vertical displacement caused by the press-fit of the ground improvement body can be offset. That is, protrusions which occur in the press-fit process are offset by the depression which occurs in the up-down process so that ground protrusion quantity can be sharply reduced through the whole construction. Thus, the more the repetition frequency of the forward and backward movement of the injection pipe is, the higher the protrusion suppression effects become. |
