Below being formed to the natural ground revised

摘要

PROBLEM TO BE SOLVED: To provide a natural ground improving agent injection apparatus which can almost simultaneously and almost uniformly inject a natural ground improving agent over the entire length of a prepared hole.;SOLUTION: According to the structure of the injection apparatus, a casing steel pipe 90 having injection holes 91 formed therein, has a plurality of packers 10 inserted therein, and an insert steel pipe 20 penetrating the packers, has filling holes 21 at locations corresponding to the locations of the respective packers 10, and discharge holes 22 at locations between the packers 10. The natural ground improving agent is fed to the insert steel pipe 20, and firstly filled in the packers 10 to inflate the same. Thereafter, the improving agent is discharged into the casing steel pipe 90 which is partitioned due to the inflation, via the discharge holes 22, and further injected into the natural ground via the injection holes 91. Herein a discharge pressure for opening a discharge constant pressure on-off valve 60 arranged at the discharge hole 22 is set higher than a filling pressure for opening a filling constant pressure on-off valve 50 arranged at the injection hole 21, and varied so as to have a higher value at a location closer to the tip of the insert steel pipe 20.;COPYRIGHT: (C)2006,JPO&NCIPI