| 摘要 |
PURPOSE: To easily and accurately perform the curve excavation having the short radius by alternately repeating a process of excavating the front surface by a front surface cutter bit and a process of excavating the side surface by a side surface cutter bit simultaneously with front surface excavation. CONSTITUTION: A shield A is advanced by thrust of a jack 6 while a front face is excavated by a front surface cutter bit 5. Next, simultaneously with excavation of the front surface, the side surface excavation is performed by a side surface cutter bit 11, and thrust of the jack 6 is adjusted to advance the shield A while changing the direction. A process of the straight excavation and a process of changing the direction are combined and alternately performed so as to be conformed to the desired estimated passing passage. |
