| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To bring a sealing mechanism of a buoyant material (a) into correspondence with a change in an outer diameter of a new pipe 2 at the time the new pipe 2 is propelled and inserted by receiving buoyant force. <P>SOLUTION: In the case of a direct pipe part, the amount of supply of a fluid b to shrinking and swelling tubes 12a, 12b for sealing is increased. Then at the time of the transition from the direct pipe part to a joint part, a supply pressure is decreased (the fluid is discharged) in accordance with a change in a diameter with the transition, thus an appropriate contact pressure is realized. When the action opposite to it is performed at the time of transition from the joint part to the direct pipe part, and the degree of expansion of the tube 12 is adjusted, an appropriate contact pressure can be obtained even when there is a change in a diameter on the outer peripheral surface of the new pipe 2. Thus a leak of the buoyant material (a) can be prevented with reliability. Then a cap, which is put on the head of the new pipe 2 inserted in the forefront, is engaged with a jig at the other end of a sheath pipe 1, thus the new pipe is centered. The buoyant material (a) is adopted which hardens after the whole new pipe 2 is inserted to the sheath pipe 1, and also serves as a filling material. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
