| 摘要 |
PURPOSE:To prevent promotion of pit wall collapse in the course of tunnel excavation by installing a gripper block in a freely sliding manner on the main beam of a tunnel excavator while installing a rotating bracket on the outside circumference of the gripper block, and then carrying out installation of a gripper. CONSTITUTION:A propelling jack 9 is extended while a cutter head 4 is rotated to carry out excavation, and the excavation is stopped porarily when the propelling jack 9 is fully extended. A leg 14 is extended thereafter to support an excavator. A gripper 13 is then removed from the pit wall and a gripper block 12 is moved forward with the propelling jack 9 contracted. The gripper 13 is pushed against the pit wall again and, if a collapsed portion (p) is found on the pit wall, a rotating bracket 15 is rotated so as to avoid the collapsed portion (p). Excavating work is commenced with a gripper jack 8 extended, the gripper 13 attached to the pit wall and the leg 14 contracted. An excavator can thus advance accurately preventing the excavator from causing slippage. |
