OUTBREAK DEVICE FOR SHIELD BORING MACHINE

PROBLEM TO BE SOLVED: To solve problems of difficulty in outbreak in a novel material shield- cuttable tunnel-wall of an arrival vertical shaft because of damage or defective in a cutting bit of an outbreak device for the novel material shield-cuttable tunnel-wall caused by a hard obstacle buried in natural ground in boring the natural ground after a shield boring machine passes a starting vertical shaft. SOLUTION: A device is provided with a rotary cutter device to drive rotation of a cutter blade 3a by a rotation drive device in the condition where the cutter blade 3a is protruded from an outer circumferential surface of a shield frame 2 before protruded parts 5, 8. It is also provided with a first cutting bit line comprising plural cutting bits 4 disposed in parallel in an axial direction to be protruded from the outer circumferential surface of the shield frame 2, and a second cutting bit line comprising plural cutting bits 4 disposed in parallel in an axial direction to be protruded from the outer circumferential surface of the shield frame 2. The first cutting bit line and the second cutting bit line are disposed in the middle of the rotary cutter device 3 and the protruded parts 5, 8, and they are disposed in such a way that intervals between both get gradually larger as they go backward.