| 摘要 |
PURPOSE:To excavate a single-track tunnel in continuity to a double-track tunnel by installing shield units of a parallel type shield machine in the left and right hollows of a frame having a hollow cocoon-form section in such a way as capable of individually excavating together with or separate from the frame. CONSTITUTION:A parallel type shield machine 1 is installed in a pit excavated by the open cut method, to make simultaneous excavation of a double-track tunnel, wherein the internal circumference of the tunnel at its tail is covered with soil. When this parallel type shield machine 1 reaches a branch point of tunnel, the left and right shield units 4, 4 are separated by a frame 2 and also separated from each other. Then, single-track tunnels are excavated individually by the shield units 4, 4, and covering work is made to the internal circumference of tunnel. The frame 2 is installed as reinforcement at tunnel branch. This permits simple execution of works for branch point and shortens the period of construction to a great extent. |
