| 摘要 |
PROBLEM TO BE SOLVED: To excavate a tunnel having an arbitrary sectional form in a simple structure by providing a boring part for boring the natural ground, which is a rotor adapted to rotate round a shaft extended in the vertical direction. SOLUTION: A shield 10 comprises a front drum part 12 and a rear drum part 14, and is expanded and contracted. A boring part 20 is a dome-form, and the surface thereof is provided with a roller bit 22 and a scraper. The shield 10 is provided with a shaft 30, a bearing part 28 is provided in the inside of the boring part 20, and the boring part 20 is rotated round the shaft 30. Therefore, the bearing part 28 is provided with a gear 32, and driven in rotation by a motor 34 and a gear 36. The shaft 30 is a little inclined forward. Thus, the whole of the shaft 30 inside the tunnel excavated by the boring part 20 is positioned so as to enable boring. Accordingly, the section of excavation is equal to the form of the boring part 20 seen from the front, so that a tunnel having an arbitrary section can be excavated. |
