| 摘要 |
PURPOSE:To improve agitating of an improving agent and to increase a ground improving effect, by a method wherein a position of a jet nozzle for an ground improving agent is switched corresponding to processes to insert a rotary shaft, equipped with upper-stage and lower-stage agitating vanes, into a ground and to pull it off. CONSTITUTION:If a rotary shaft 30 of an agitating vane is inserted downward into a ground, a switching valve body 43 is pressed against a bottom (40) side of an outer tube 31 to raise an expansive inner tube 31 to raise an expansive inner tube 34a, a switching feed hole 36 is connected to a jet nozzle 33, an improving agent, fed by pressure into an inner tube 34, is jetted into a ground through the jet nozzle 33, and the agent is consecutively and repeatedly agitated, in the order, by agitating vanes 5c and 5a. If the rotary shaft 30 is pulled and raised after it reaches a given depth, the expansive inner tube 3 is lowered by a tension spring 48 through the guidance of a bracket 46 and a guide notch 47, a switching feed hole 35 coincides a jet nozzle 32, and the improving agent, jetted into a ground through the nozzle 32, is consecutively and repeatedly agitated, in order, by the agitating vanes 5a and 5c. |
