| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a tunnel excavator which can form a renewal pipe line having a larger diameter than an existing pipe line precisely and efficiently while the existing pipe line such as an old sewage pipe is being crushed by the excavator. SOLUTION: A cylindrical hood member 4 projecting forward from the central portion of a cutter plate 2 of a tunnel excavator C is inserted into the rear end of an opening of an existing pipe line A to advance the excavator C precisely in the length direction of the pipe line A. And at the same time, the pipe line A is supported by the outer circumferential surface of the member 4 to prevent the pipe line A from being vibrated by crushing bits 8 mounted to the cutter plate 2 when the pipe line A is crushed into small pieces by the bits 8. Further the ground around the pipe line A is excavated by crushing bits 9 mounted to the plate 2 to form a new pipe line B at the rear of the excavator C.</p> |
