| 摘要 |
PROBLEM TO BE SOLVED: To provide a tunnel construction method by which when the natural ground above a widening section between a preconstructed pair of tunnels is excavated to form an upper space, the upper space can be formed efficiently as the natural ground is supported firmly to improve constructibility and reduce construction costs in construction of a large-section tunnel. SOLUTION: A curve pipe roof 4 is placed by driving on a part of a widening section L in a tunnel axis direction O1 along which a pair of tunnels are constructed to be communicated with each other. While the curve pipe roof 4 supports the natural ground G in advance, an upper space 5a above a curve pipe roof installing section L1 is preformed, and an elongated steel pipe 13 is placed by driving in the tunnel axis direction O1 through the upper space 5a above the curve pipe roof installing section L1. The natural ground G above an elongated steel pipe installing section L2 is excavated as the natural ground G is supported in advance by the elongated steel pipe 13 so that the upper space 5a above the curve pipe roof installing section L1 is extended sequentially in the tunnel axis direction O1. In this manner, an upper space 5 communicating across the entire part of the widening section L is formed. COPYRIGHT: (C)2009,JPO&INPIT |
