SHIELD EXCAVATOR

PROBLEM TO BE SOLVED: To contrive a quick response and enhance excavation efficiency by vertically and horizontally swinging a plurality of various kinds of cutter bits arranged to be spacedly scattered in a planar shape and advancing the cutter bits by a pipe jacking member frontward. SOLUTION: In the case where a shield tunnel or the like rectangular in a cross section is excavated and formed, a shaft in the underground is excavated to set a shield excavator therein. Then, the rear end of a pipe jacking device is locked on the side of the shaft to swing a cutter bit 1 so as to be excavated and advanced. A segment 19 is attached to an outer periphery excavated in a rectangular shape in the cross section by a segment assembling device 18 on the rear part of the excavator to form a rectangular cross section tunnel finally. Thus, excavation load for a plurality of the cutter bits 1 is averaged to uniformly wear the cutter bit 1, a wear amount is smaller than in a rotary excavator, and excavation drive force is also lessened. Thereby excavation efficiency is improved to largely contribute to the reduction of a cost and a process needed for work.