| 摘要 |
PROBLEM TO BE SOLVED: To provide an arrival portal cut-off method for preventing sediment from flowing out of a clearance between a boring machine and an arrival portal and a clearance between a pipe body and the arrival portal even if contour dimensions of the boring machine and a case body differ greatly. SOLUTION: The arrival portal cut-off method comprises a process for arranging a first annular blocking member 7 of the arrival portal 3 and bringing the first annular blocking member 7 into contact with the outer periphery of the boring machine 4 to block the clearance between the boring machine 4 and the arrival portal 3 when the boring machine 4 reaches the arrival portal 3; a process for previously arranging a second annular blocking member 8 fixedly at the rear end of the boring machine 4 to come in contact with the outer periphery of the case body 6; and a process for blocking a clearance between the case body 6 and the arrival portal 3 by releasing the fixation of the second annular blocking member 8 to the boring machine 4 and mounting the second annular blocking member 8 to the first annular blocking member 7 when the second annular blocking member 8 reaches to come in contact with the first annular blocking member 7. COPYRIGHT: (C)2006,JPO&NCIPI
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