| 摘要 |
PROBLEM TO BE SOLVED: To prevent a soil improving agent from leaking (spurting upward) from a soil improving agent injection device, its periphery and the peripheral ground (the infiltration diameter of the impregnated soil improving agent) when injecting the soil improving agent. SOLUTION: An outer pipe 1, an intermediate pipe 2 and an inner pipe 4 closed at the lower ends are concentrically disposed. Soil improving agent supply paths 10, 11 are formed inside the inner pipe 4 and in a clearance between the inner pipe 4 and intermediate pipe 2, and an air supply path 8 is formed in a clearance between the outer pipe 1 and intermediate pipe 2. Soil improving agent outflow pores 3d, 3e communicating with the soil improving agent supply paths 10, 11 are opened in vertical proximity to a peripheral wall near the lower end part, and air blowoff pores 1d communicating with the air supply path 8 are opened to the peripheral wall positioned above the openings of the pores 3d, 3e. A soil improving agent injection device A of such constitution is inserted in a boring hole C, and a soil improving agent is injected from the soil improving agent outflow pores 3d, 3e. At the same time, air is blown off from the air blowoff pores 1d to form an air barrier, and lifting is performed while injecting the soil improving agent.
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