Shallow tunnel excavation method

摘要

PROBLEM TO BE SOLVED: To facilitate an operation to assemble a new segment while maintaining a ring shape of segments in an excavation pit.SOLUTION: An upper expansion type segment holding device 15 installed on a rear end side of a screw conveyor 10 of the shield machine and an upper/lower expansion type segment holding device 16 provided behind it are provided as a segment holding device which holds a segment SG when excavating an excavation pit by the shield machine 1, While a ring shape of the segment SG is excellently held, a new segment SG can be easily conveyed and supplied to a segment assembly position through operations of those segment holding devices 15, 16 without being disturbed by the segment holding devices 15, 16.