| 摘要 |
PROBLEM TO BE SOLVED: To provide a double pipe jacking construction method for achieving smooth and accurate jacking work for a longer jacking distance while surely preventing the entry of sediment from a ground side into a tunneling device of either a double cylinder structure or a double buried pipe type. SOLUTION: The tunneling device comprises an inside cylinder body 70 having an outer diameter corresponding to a first buried pipe 30 connected to the rear side, an outside cylinder body 60 spaced from the outer peripheral face of the inside cylinder body 70 and having an outer diameter corresponding to a second buried pipe 20 connected to the rear side, a mounting and demounting change-over means 74 for changing over the outside cylinder body 60 and the inside cylinder body 70 between an axially fixed state and a moving state, an excavation means 50 having an outer excavation diameter selectively changeable on the front face of the inside cylinder body 70, a flow-in preventing ring 68 for blocking a gap between the outside cylinder body 60 at its front end and the inside cylinder body 70, and a waterproof member 66 arranged on the inner peripheral face of the outside cylinder body 60 on the rear side of the flow-in preventing ring 68 and having an elastically deformable front end abutting on the outer peripheral face of the inside cylinder body 70. COPYRIGHT: (C)2006,JPO&NCIPI
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