| 摘要 |
PROBLEM TO BE SOLVED: To provide a shield technique capable of reducing a bending moment acting on copy cutters when excavating an underground pit of a rectangular cross section by cutter heads and the copy cutters. SOLUTION: This earth pressure balancing type shield machine is provided with a shield body 1 having a rectangular face, a plurality of cutter heads 2 formed by attaching cutter bits 2c to cutter spokes 2b and arranged as partially overlapping the rotation loci, and copy cutters 3 projected from the tips of the cutter spokes 2b and implementing outbreak. The rotation loci (s) in the tip of the cutter spoke 2b are forced out of the respective long sides of the rectangular face of the shield body 1 so as to excavate excessively; a plurality of cutter heads are formed and arranged so as to form parts (b) left unexcavated in the four corners, etc., in the rectangular face of the shield body 1; and the cutter heads 2 and the copy cutters 3 are cooperated so as to excavate the underground pit of the rectangular cross section. |
