| 摘要 |
PROBLEM TO BE SOLVED: To safely and rapidly excavate a large cross section tunnel by previously reinforcing and improving the natural ground over the whole length of a construction area of a tunnel. SOLUTION: After a topped guide pit 2 is excavated to pierce the whole length of a construciton area of a tunnel 1, bend drilling is performed along the peripheral edge of cross section of the tunnel 1 at specified space from the topped guide pit 2. After inserting filling pipes in drilled holes, bent steel pipes 3 are pulled out, and filling material is filled from the filling pipes to construct an artificial natural ground arch 4. The tunnel 1 is then excavated, and a hanging form 6 is advanced to place concrete for secondary lining, thus excavating the tunnel. |
