CONSTRUCTION METHOD FOR ESTABLISHING UNDERGROUND COLUMN AND DEVICE THEREFOR

PROBLEM TO BE SOLVED: To excavate and stir the ground while avoiding the damage by cobble stones by extending a flexible wing provided on an injection rod sideways in a prescribed depth, and retreating it while a ground hardener is injected from a side nozzle. SOLUTION: An injection rod has an excavating chip and an excavating directional injection nozzle 6 on the top part, and a side injection nozzle 6' on the upper circumference. A wing W formed of a link of flexible material having a side bit 12 is provided in a position for stirring the side jet flow track so that it is protruded sideways when a cylinder rod 17 is advanced by the oil pressure of a hydraulic cylinder 17' and contracted along the injection rod when it is retreated. The injection rod is rotated and advanced toward a target ground A while a lubricating material is injected through the injection nozzle 6 in the state where the wing W is contracted. When it reaches a prescribed depth, the wing W is extended, a ground hardener is injected through the injection nozzle 6' while retreating, the wing W is also rotated to excavate and stir the peripheral soil, and the ground hardener is mixed thereto.