WIDENING SHIELD MACHINE

PROBLEM TO BE SOLVED: To provide a tunnel excavator which can excavate a preferable tunnel at a confluent portion and a divergent portion fitted for the case where the tunnel is constructed under the ground at a very deep location. SOLUTION: The tunnel excavator is formed of a front section shield machine 2 equipped with a front section cutter head 6, a widening section shield machine 3 protrudably housing therein widening section cutter heads 31, and a rear section shield machine 4 for assembling segments along an excavated section excavated by the front section cutter head 6. Excavation of the entire tunnel excavator is achieved by receiving excavation reaction of the front section shield machine 2 by the rear section shield machine 4. Herein the tunnel excavator is comprised of a housing gate 26, protruding jacks, a mud feeding pipe 36, and a mud discharging pipe 37. The housing gate 26 is arranged on the rear of the front section shield machine 2, for covering a peripheral surface of the widening section shield machine 3. The protruding jacks are provided for the widening section shield machine 3, for protruding the widening section cutter heads 31 of the widening section shield machine 3, after driving only of the front section shield machine 2 and therefore advancing of the housing gate 26 to expose the peripheral surface of the widening section shield machine 3 to the outside. The mud feeding pipe 36 and the mud discharging pipe 37 are provided for the widening section shield machine 3 and function to discharge excavated soil. COPYRIGHT: (C)2006,JPO&NCIPI