| 摘要 |
PROBLEM TO BE SOLVED: To continuously excavate a long-distance tunnel without reducing boring efficiency by a tunnel boring machine and a tunnel boring method. SOLUTION: A plurality of second cutter bits 21 are provided along the radial direction at inner storage positions separately from first cutter bits 18 invariably protruded forward on a cutter head 12. When the first cutter bits are abraded, or when the bulkhead section of a vertical shaft formed with a strong concrete wall is to be ruptured, the second cutter bits 21 are extruded forward by extruding jacks 22, and boring is conducted by using the new and sharp second cutter bits 21. |
