| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to efficiently and safely excavate a super-hard bedrock without crushing it into pieces. SOLUTION: A heading 2 is excavated in a bedrock, and after a pair of front and rear boring holes 3a are bored in the upper part thereof, cutting wires 4a of a wire saw 4 pass through a pair of front and rear boring holes 3a to stretch them to the bedrock so that the bedrock can be cut toward the inside of the bedrock from the surface of the bedrock in the case it is pulled, and the upper part of the bedrock is cut off. In the same way, the cutting wires 4a pass through one of a pair of front and rear boring holes 3a and the heading 2 to stretch them to the bedrock, and the side of the bedrock is cut off. Then, after the cutting wires 4a pass through an upper cut groove formed in the case the upper part of the bedrock and a pair of side cut grooves formed in the case the side of the bedrock is cut off, they are led out to an outside space, the rear side of the bedrock is sawed off to cut off a cut block, and such cutting-off work is progressed toward the circumferential direction to excavate a tunnel in the super-hard bedrock. |
