| 摘要 |
PURPOSE:To permit a tunnel to be constructed by a push tube, and enable curved construction work to be performed by a method in which limitless distance excavation is made without providing shafts on the junction point. CONSTITUTION:A shield device 12 is advanced to form a drift 31 of usual cross section corresponding to the cross section of a long circular precast tube 11, and the precast tube 11 is pushed into the drift 31 from the pit port 3a. Afterwards, a junction point 33 is formed in such a way as to widen the width of the drift 3 and the drift 31 of usual cross section is again formed from the junction point 33. The precast tube 11 transported to the junction point 33 is inverted and pushed into the drift 31 repeatedly for a given distance. |
