| 摘要 |
PROBLEM TO BE SOLVED: To always advance a shield excavator straight by contracting propulsive jacks corresponding to a space where segments are assembled and propulsive jacks positioned at the opposite side and advancing the shield excavator by other propulsive jacks. SOLUTION: A cutter plate is arranged at the front shell and a plurality of positions of the inner peripheral face of the front and rear shells are connected by middle-folding jacks and the rear shell is equipped with propulsive jacks 17. Rods for propulsive jacks 17 corresponding to the a space 4 and propulsive jacks 17A for a space 4A oppositely positioned in the diametral direction are contracted respectively and separated from the spaces. Further, the propulsive rods of other jacks 17 are stretched to advance the shield excavator. Hexagonal segments 2 are assembled and the rod ends of the propulsive jacks 17, 17A are stretched to come into contact with the excavator and give an propulsive force to the excavator. Then, the rods of propulsive jacks 17 for the following spaces are contracted to separate from the spaces. In this way, new hexagonal segments are repeatedly assembled in spaces in the same way and a precise tunnel can be constructed. |
