| 摘要 |
PROBLEM TO BE SOLVED: To improve execution by supporting a gripper shoe by a spacer guide having an arc sliding face, and enlarging the projection amount of a cutting face front end more than the rear end. SOLUTION: A frame-like gripper casing 32 is fixed in an opening 2 provided on the skin plate 56 of a rear drum, and a gripper shoe 10 is held through a spacer guide 33 at the inner face prescribed position to constitute a gripper device 1. The abutted face of the guide 33 and the shoe 10 is in the arcuate form, and the guide 33 guides the rotation of the shoe 10. In addition, when the shoe 10 is pushed out to the soil and mountain face of a tunnel, a part is projected from the surface of the plate 56 up to only a prescribed amount along the inner peripheral face of the casing 32 in order to support the shoe 10. In the case where a soft layer is excavated, the cylinder rods of hydraulic jacks 20A, 20B are projected up to only a prescribed amount, the rod of the frontward jack 20A is extended further, and the front end 10a of the shoe 10 is sufficiently bitten into soil and mountain. As a result, jacking reaction force at the time of excavation can be secured. |
