| 摘要 |
<p>PURPOSE:To miniaturize a bore diameter of a new pipe duct by providing a first shield excavator circularly excavating the outer peripheral part, regarding a laid pipe duct as a guide, and a neighboring second excavator excavating a working pit, and carrying materials and machine parts into and out of the working pit. CONSTITUTION:A first shield excavator 10 equipped with a head cutter 11 for the purpose of circularly excavating the outer periphery as making a laid pipe duct 30 a guide is provided. Next, a second shield excavator 20 neighboring the excavator 10 and equipped with a freely oscilatable head cutter 21 is provided. Next, the outer peripheral part of the pipe duct 30 is excavated with the excavator 10 while a working pit B is excavated with the excavator 20, and obstruction is avoided with a oscillating mechanism if necessity demands. Materials, machine parts, scrapped materials and the like are carried through the pit B, while the covering of the new pipe duct A and the pit B and the removal of the pipe duct 30 are performed. It is possible thereby to secure a working space without excessive enlargement of a bore diameter of the new pipe duct, and to work effectively.</p> |
