| 摘要 |
PURPOSE:To reduce the excavation torque of an oval tunnel having high degree of flatness by providing a cutter device capable of expansion of an excavation diameter as well as rotating and sliding to the front of shield shell excavation having an oval section. CONSTITUTION:An opening and shuttling jack 2 having a rod capable of expanding to the side of a facing is provided to the front of excavation. After that, sliding jacks 3 and 3 are provided, and a jack case 22 is held with each of tips of the expansion rods to make it possible to slide the opening and shuttling jack 2 right and left. Then, umbrella shaped spokes 4 having excavation bits 42 are arranged and pivoted radially to make is possible to open and close like an umbrella. The spokes 4 are rotated, opening the spokes 4 at the central part to have the maximum diameter while sliding them with the jacks 3, and the spokes 4 are gradually closed to have the minimum diameter until both ends. According to the constitution, earth pressure can be reduced with a small excavation diameter to excavate a flat and oval tunnel. |
