| 摘要 |
PROBLEM TO BE SOLVED: To provide a closed type excavator which is for use in under-path construction work carried out by a shell preceding tunnel construction method using a steel shell, contributes to a shortened construction period and reduced manpower by carrying out safe and efficient excavation, and avoids adverse effects on a structure, lines, etc. on the ground by minimizing a loose height of the natural ground, to thereby improve earth pressure retaining force and ensure earth pressure balance. SOLUTION: The closed type excavator 9 is formed of a cutter element 20 for excavating the natural ground R, a driving means 21 for driving the cutter element 20, and a shield cylinder body 22 for holding them. The shield cylinder body 22 is formed of a cylinder trunk section 25, and a movable roof 27 overhanging in an excavating direction according to extension of a movable means 26. According to the closed type excavating method, the movable roof 27 is overhung in the excavating direction prior to excavation of the natural ground R by the cutter element 20. COPYRIGHT: (C)2006,JPO&NCIPI |
