COMPACTION METHOD OF GROUND

PROBLEM TO BE SOLVED: To provide a compaction method of the ground capable of firmly compacting the peripheral ground of an excavated hole when the ground is compacted by making use of rotary power of a special auger used for ground improvement. SOLUTION: An excavated soil is pushed against the circumferential wall of the excavated hole 102 by boring the hole in theground 100 as the object of compaction by rotatably driving the special auger 10. At the beginning, the ground at the located around the excavated hole 102 is replaced with the excavated soil to form an excavated soil compressional compaction zone 104. In that time, a natural ground compressional compaction zone 110 is formed in the circumferential side. Then, the special auger 10 is once pulled out from the excavated hole 102 to dump a predetermined amount of improved material into the excavated hole 102, and the improved material is pushed against the circumferential wall of the excavated hole 102 by again boring the hole with the special auger 10. Thereby, the excavated soil compressional compaction zone 104 and the natural ground compressional compaction zone 110 are pushed out to the circumferential side to expand an extent of the natural ground compressional compaction zone 110 and, at the same time, an improved material compressional compaction zone 108 is formed in the inside circumferential side.