| 摘要 |
PURPOSE:To stabilize and open the working face for the excavating work of a tunnel when the tunnel having a large cross section is excavated in particular in the excavating method of the tunnel using a skin plate covering the outer periphery of the tunnel. CONSTITUTION:The cross sectional region including the upper half outer peripheral portion to the tunnel working face is precedingly excavated into a circular arc shape while a ring cut 13 is left, and an upper half skin plate 2 is advanced to quickly cover the natural ground of the upper half outer periphery 12 exposed by it. The ring cut 13 is excavated from the rear by the excavator 6, and a lower half skin plate 3 is advanced to cover the natural ground of the lower half outer periphery of a tunnel. An upper half skin plate 2 is advanced, the ring cut 13 is left by the prescribed length, the upper half outer peripheral portion of the tunnel working face is precedingly excavated, and the ring cut 13 is excavated. These processes are repeated in sequence in turn to excavate the tunnel. |
