| 摘要 |
<p>PROBLEM TO BE SOLVED: To close a bedrock between an existing structure and a cutting edge generated at the time of joining, and to attain the safety of joining works by forming a cutting edge device of a shell, in which both ends are opened, and an internal cylinder installed in an extensible manner from the inside of the shell and forming the front end face of the internal cylinder in the shape of a connecting section with the existing structure. SOLUTION: The cutting edge device 1 is propelled in such a manner that a shell 2 is placed at the front end of a propulsive pipe 4 and the propulsive pipe 4 is extended while the shell 2 is penetrated to a bedrock. When the end section of the shell 2 reaches a pipe body 5, the welding section of the shell 2 and an internal cylinder 3 is separated. The internal cylinder 3 is elongated towards the pipe body 5 from the inside of the shell 2. The elongation force transmits the thrust of a jack to the internal cylinder 3 through the propulsive pipe 4. Since the end section of the internal cylinder 3 is molded in conformity with the shape of the side face of the pipe body 5 at that time, the end section of the internal cylinder 3 coincides with the pipe body 5 approximately accurately when the end section of the shell 2 reaches the pipe body 5, and is joined. That is, the connecting works of the propulsive pipe 5 are conducted under the state, in which a cover is mounted on the bedrock between the shell 2 and the pipe body 5 at all times. Accordingly, the generation of a defective joining section between the propulsive pipe 4 and a section to be joined can be prevented.</p> |
