| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently secure construction safety and cut-off properties when a preconstructed tunnel is widened. SOLUTION: When the preconstructed tunnel (main tunnel 1) is widened, a soil improving body 4 surrounding an area to be widened is constructed. The soil improving body is constituted as a multiple structure which is composed of a reinforced portion 4A undergoing injection of a suspension-type grout material, and a cut-off portion 4B undergoing injection of a solution-type grout material; and a plurality of impervious walls 6 are formed inside the multiple structure, so that the inside of the soil improving body are divided into a plurality of impervious areas 7. In the construction of the soil improving body 4, the injection of a chemical solution is performed gradually. A steel pipe forepiling method is carried out as an auxiliary construction method in the widening of the tunnel. Cut-off performance is checked by performing a drainage test for the impervious areas in advance of the widening of the tunnel. COPYRIGHT: (C)2010,JPO&INPIT |
