PURPOSE: To increase workability and cutting off effect of water even if a compressive or tensile displacement is caused in a closed conduit, by providing collars in exterial and interial cylinders respectively and interposing cutting off ring packings of water between the collars.
CONSTITUTION: At least one piece of first collar 6 is formed as a unit at the inner peripheral face of an external cylinder 3 fitted at the end of one of cylinders in a closed conduit and at least two pieces of second collars 15, 16 are formed as a unit at the outer peripheral face of an internal cylinder 11 fitted at the end of the other cylinder. Next, water cutting off ring packings 20, 21 are interposed respectively in the space surrounded by the external and internal cylinders 3, 11 and the first and second collars 6, 15, 16. And when a compressive or tensile displacement is caused in the closed conduit, the clearance between the first collar 6 and one of the second collars 15, 16 becomes narrow and one of the interposed water cutting off packings 20, 21 is compressed to become effective in cutting off of water.
URUTA HISAYA
TSUKAGAWA YUKIO
Next Patent: CONJUNCTION SEGMENT AND MULTI-CIRCULAR SECTION SHIELD TUNNEL PROVIDED THEREWITH