| 摘要 |
PROBLEM TO BE SOLVED: To provide a widening type shield boring machine capable of stably excavating a widening cross section without causing the increase of propulsion resistance and while preventing the collapse of a bedrock. SOLUTION: The widening type shield boring machine includes a shield body 1 having the first cutter head in the front section to excavate a standard cross section, a widening opening section 12 formed in a skin plate 1a of the shield body 1, an approximately columnar pressure holding chamber 13 having an axial center parallel with the axial center of a shield formed by communicating with the widening opening section 12, a turning casing 14 placed in the pressure holding chamber 13 in a turnable manner and enabling the widening opening section 12 to freely open and close by an outer circumferential wall 14a and the second cutter head 11 enabling it to come in and out to the outside through the widening opening section 12 from an opened opening section 14c formed in the outer circumferential wall 14a in the turning casing 14 and consisting of a rotatable drum-shaped cutter having a large diameter around the axial center parallel with the shield axial center. COPYRIGHT: (C)2006,JPO&NCIPI |
