Application manner null of support body to tunnel excavation

摘要

PROBLEM TO BE SOLVED: To provide the execution method of a support body capable of accurately supporting the upper peripheral wall part of a tunnel wall face in which a bedrock is easy to collapse. SOLUTION: A ring-like support body which is smaller diameter than a tunnel excavation wall face T by a plurality of support pieces 1, 1A, 1B and stretching a bedrock collapse prevention member 2 composed of a wire gauze on an upper half part is formed. Next, the lower support piece 1B of the ring- like support body and the support pieces 1A, 1A of both the side parts are expanded in same size by expansion jacks 5, 5, the ring-like support body is diameter-enlarged, a bedrock collapse prevention member 2 stretched on the upper half part of the ring-like support body is disposed in the state where it accurately runs along the upper peripheral wall part of the tunnel excavation wall face T without displacing the bedrock collapse prevention member 2 in the tunnel circumferential direction and loose load by the collapse of a bedrock, fall of a rock and the like locally produced on the upper peripheral wall part of the tunnel excavation wall face T is supported.