GROUND IMPROVING METHOD

PROBLEM TO BE SOLVED: To provide a ground improving method adequate for a case in which work time and work environment are significantly restricted.SOLUTION: A ground improving method comprises following processes: to rotate a multiple pipe 10 equipped with an upper nozzle and a lower nozzle around a shaft center and penetrate the multiple pipe into the ground G while injecting a cutting liquid S from the upper nozzle; to rotate the multiple pipe 10 around the shaft center, inject the cutting liquid S or a hardener C from the upper nozzle, and pull up the multiple pipe while injecting the hardener C from the lower nozzle at 3 to 7 MPa of injection pressure. The ground G is made into cut sediment G2 by injecting the cutting liquid S. The cut sediment G2 and the hardener C are mixed to make an improvement body R.SELECTED DRAWING: Figure 1 【課題】作業時間や作業環境に大きな制約がある場合に適する地盤改良工法を提供する。【解決手段】上段ノズル及び下段ノズルを有する多重管１０を、軸心回りに回転し、かつ上段ノズルから切削液Ｓを噴射しつつ地盤Ｇに貫入する工程と、多重管１０を、軸心回りに回転し、かつ上段ノズルから切削液Ｓ又は硬化材Ｃを噴射し、下段ノズルから硬化材Ｃを３〜７ＭＰａの噴射圧で噴射しつつ引き上げる工程とを有するものとする。そして、切削液Ｓを噴射して地盤Ｇを切削土砂Ｇ２とし、この切削土砂Ｇ２と硬化材Ｃとを混合して改良体Ｒとする。【選択図】図１