| 摘要 |
PROBLEM TO BE SOLVED: To increase the air recovery efficiency by forming a connection pipe in an excavation and agitation blade to extend a force-feed passage in a rotary shaft and opening the connection pipe end to the upper face of the tip of the excavation and agitation blade to form a jet opening. SOLUTION: Compressed air and a ground-improving powdery material force- fed through a force-feed passage 8 in a rotary shaft 2 is led from the force-feed passage 8 to a connection pipe 7, and ejected from a jet opening 9, when pulling an excavation and agitation blade 1 and the rotary shaft 2 inserted in the ground. The flowing speed varies when these materials are ejected from the jet opening 9 into the ground and the compressed air is separated from the ground-improving material, the ground-improving material is dispersed among the soil and penetrated therein, and further it is forcibly mixed with the soil by the rotation of the excavation and agitation blade 1. The compressed air reaches the outer peripheral face of the rotary shaft 2 and rises along the peripheral face and it is discharged to the ground level. Accordingly, the ejected air can be securely led to the outer peripheral face of the rotary shaft and the recovery efficiency of air can be improved.
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