| 摘要 |
PROBLEM TO BE SOLVED: To reduce a manufacturing cost without requiring a broad site near a tunnel opening. SOLUTION: A back filling grout material G is prepared by using water W, bentonite B, a hardening retarder Z, hydraulic cement C and a fine aggregate s. The grout material G is divided into bentonite slurry s and mortar M and they are respectively prepared at each different place. For the slurry S, a slurry- preparing apparatus 12 is installed neat the opening of the tunnel 10 to be constructed, and it is prepared here. The mortar M is prepared by using the cement C, the fine aggregate s and water at a ready mixing concrete factory. The mortar M is stored in a drum 18 capable of mixing and stirring and carried to the construction site of the tunnel 10. A specific amount of the hardening retarder Z and the slurry S stored in a tank 12d are added to the mortar M carried by a wagon 18. By rotating the drum 18 at a high speed, the mortar M and the slurry S are mixed and stirred to prepare the back filling grout material G.
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