| 摘要 |
PURPOSE:To shorten the period of construction as well as easily widen the width of excavated pit. CONSTITUTION:A curved tube 14 having a movable shoe 54 and an inner tube 44 equipped with an excavator 60 are advanced from the inside of a shield tunnel 10 toward the surrounding of a width-expanding portion 18. The bit 74 of the excavator 60 is turned, the excavator 60 is advanced while correcting its direction on the basis of an information of advancing positions measured by an optical fiber gyro 78 to bury the tube 14 in the surrounding of the portion 18. Afterwards, under the condition that the tube 14 is left behind, the inner tube 44 is pulled out with the excavator 60 from the tube 14, and a grout- injecting tube is inserted into the tube 14. A grout such as cement milk or a freezing agent is injected into the injecting tube to improve the surrounding ground of the portion 18. After the ground is improved, the width of the portion is expanded. |
