| 摘要 |
PROBLEM TO BE SOLVED: To reinforce a natural ground well regardless of geological conditions without requiring dedicated machines, relating to a method for reinforcing the natural ground for, e.g. tunnel timbering, and relating also to reinforcement. SOLUTION: In this method for reinforcing the natural ground, a hollow drill head 6 having a bit is provided integrally with the end of a hollow drill rod 5 attached to a drilling machine, and a center bit 7 is removably mounted within the drill head 6; after the driving force of the drilling machine is transmitted to the drill rod 5 and the center bit 7 and a hole is drilled, long rod-shaped reinforcement 20 is inserted into the drill rod 5 and the drill head 6, and the center rod is detached ahead of the drill head 6, after which the drill rod 5 and the drill head 6 are drawn out of the drillhole and recovered while the center bit 7 and the reinforcement 20 are left behind in the drillhole. A slipoff preventive locking tool 23 which flares radially outwards when the drill rod 5 and the drill head 6 are drawn out of the drillhole is provide at the tip of the reinforcement 20.
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