| 摘要 |
PURPOSE: To stabilize replacement by installing a holding jack between a main frame bearing a pilot-pit excavating beam and a main gripper and bearing a gripper holder by the holding jack at the time of replace. CONSTITUTION: A main beam 4 excavating a pilot pit 2 is extended at the central section of a cutter head 7 for a tunnel excavator 1 excavating a large- diameter tunnel while the end section of the main beam 4 is fixed onto a main frame 5. The main frame 5 is connected to a main gripper 13 through a thrust jack 23 while a holding jack 24 is coupled. When excavation at a fixed distance is completed and the main gripper 13 is replaced, a main-gripper jack holder is supported by the holding jack 24 while a gripper jack is shrunk, and gripper shoes 17 are separated from a wall surface 3 and moved. The main frame 5 is fixed onto the wall surface 3 from a side support 10 at that time. Accordingly, replacement can be conducted stably. |
