| 摘要 |
PROBLEM TO BE SOLVED: To provide an excavation advancing device with excellent practicability allowing replacement of cut-off packing without causing the infiltration of spring water of the natural ground from a clearance between pipe members in the fitted state. SOLUTION: This excavation advancing device has an excavating part 4 at the tip, and the n pieces of pipe members 1 disposed behind the excavating part 4. Two adjacent pipe members 1 are provided in a fitted state. The natural ground is excavated by the excavating part 4, and the adjacent other pipe member 1 is slidingly advanced in relation to one pipe member 1. The cut-off packing 5 for closing a clearance between the outer peripheral surface of the inner pipe member 1 and the inner peripheral surface of the outer pipe member 1 out of two adjacent pipe members 1 is detachably disposed in the clearance, and a member for closing a clearance between the outer peripheral surface of the inner pipe member 1 and the inner peripheral surface of the outer pipe member 1 at an optional time serving as the cut-off packing is deposed in the clearance between the outer peripheral surface of the inner pipe member 1 and the inner peripheral surface of the outer pipe member 1, near the cut-off packing 5.
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