BORING MACHINE

PROBLEM TO BE SOLVED: To provide a boring machine capable of carrying out boring work while forming a hole diameter larger than an outside diameter of a cutter head. SOLUTION: The boring machine is so constituted that the cutter head 25 rotated by having a cutter bit 28 on the front end is provided to a shield cylinder body 10, high pressure water for excavation and cement or the like for improving a soft ground together with extra-high pressure water for cutting/crushing an obstacle crushing the obstacle existing in the front of the direction of boring are provided to the cutter head 25 by making a multi-functional water jet injection nozzle 32 eccentric to a rotational shaft 26 of the cutter head 25, an injection nozzle position changing mechanism 34 changing an injection position of the water jet injection nozzle 32 between a radial outside and a radial inside is provided, and the injection nozzle position changing mechanism 34 moves the water jet injection nozzle 32 to the outside from the appearance 25d of the cutter head section 25. COPYRIGHT: (C)2005,JPO&NCIPI