| 摘要 |
PROBLEM TO BE SOLVED: To easily and optimally design when excavating a tunnel having a square cross section. SOLUTION: This square shield drive machine has a main cutter head 53 for excavating a circular cross section and a convex lens shape subcutter head 54 for excavating remaining soil by the main cutter head 53, which is provided at the rear of the main cutter head and rotates at an angular velocity two times higher in reverse direction while performing revolution around the center of the rotation of main cutter head 53. The subcutter head 54 is formed in such a manner that the excavated surface 57 at one side coincides with a circle B drawn by the farthest outer edge of the main cutter head 53 every time when the main cutter head 53 rotates by 180 deg. and the excavated surface 58 at the other surface coincides with the circle B every time when the main cuter head rotates by 180 deg. with a phase difference of 90 deg.. |
