| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to join with an existing shaft while protecting the joining of an existing shaft from the collapse of the earth and sand in the joining area and maintain a high water stop ability. SOLUTION: A disk-shaped engagement groove 37 is formed on a shaft wall 35 with an over cutter 27 projected from a rotary cutter. A hood 17 of a shield frame 1 is engaged with the engagement groove 37, thereby preventing the collapse of earth and sand at the joining area and joining with a shaft where the engagement groove 37 formed on the shaft wall 36 is excavated and formed with an over cutter 27 projected from a rotary cutter 2 at the front of the shield frame 1 so that the chamfered surface may be exposed to the shield frame 1. Therefore, the tip of the hood 17 which moves along the shield frame 1 is joined with this engagement groove 37 and engaged therewith, thereby enhancing a water stop ability. |
