| 摘要 |
PURPOSE:To reduce the size of a vertical shaft for converting direction, to prevent a collapse of a pithhead for drawing-out, and to reduce the time from converting the direction to a reexcavation, by converting the direction of a shield machine whose shield tail is removed, in the vertical shaft for converting direction. CONSTITUTION:A shield machine A is advanced to the midway of a vertical shaft B for converting direction through a pithhead D for drawing-out. A shield tail (b) is removed at the pithhead D and left in the ground, and after that, a shield machine A' is converted its direction in the vertical shaft B. Then, a pressure-holding wall F and a pithhead G for reexcavation are arranged in the vertical shaft B, and after excavating temporarily by the shield machine A', preferably, the other shield tail (c) is connected, and the reexcavation is started by a shield machine A''. In this case, the removal and the connection of the shield tails (b) and (c) are carried out by a cutting and a welding, but in the other way, removing and connecting means provided at the tails (b) and (c) beforehand may be used, or the both methods may be used concurrently. |
