| 摘要 |
PROBLEM TO BE SOLVED: To make a gripper contact with a segment irregular part by uniform pressure on an overall circumference. SOLUTION: A gripper 10 is supported by reaction force by hanging the gripper 10 over from a reaction part 9 and engaging it with a segment irregular part 15 of an inner peripheral surface of an existing segment 6. When it is supported by reaction force like this, drilling is carried out by a cutter head 1 while extending a front drum part jack 4, and simultaneously, some pieces of rear drum part jacks 5 are contracted, and a space made by contraction is covered with the segment 6. An elastic body (pressure equalizing device) 13 sealing fluid in an inside hollow part is furnished on a part of the gripper 10 to engage with the segment irregular part 15, the elastic body 13 is deformed at the time of supporting reaction force, and the gripper 10 makes contact with the segment irregular part 15 uniformly on an overall circumferential surface. |
