| 摘要 |
PROBLEM TO BE SOLVED: To excavate a tunnel in the rectangular form by providing a main cutter disc of a tunnel excavator and a plurality of auxiliary cutter discs which can be oscillated on the periphery of the main cutter disc. SOLUTION: Main cutter discs 2A, 2B are provided and auxiliary cutter discs 20B are provided on the periphery of the discs 2A, 2b so as to be oscillated in a direction of arrow J. A plurality of main cutter discs 2A, 2B are disposed side by side so as not contact each other and so as to be alternately, vertically offset from one another in a partially lapping relationship in a plan view. An auxiliary cutter disc 20A also is disposed at the center of the distance between the axes of the adjacent main cutter discs 2A, 2B so as to be oscillated in a direction of arrow K. The auxiliary cutter discs 20A, 20B excavate unexcavated portion of soil of the discs 2A, 2B, and hence a tunnel having a nearly rectangular cross section can be excavated. |
