| 摘要 |
PROBLEM TO BE SOLVED: To provide an enlarged shield method capable of simultaneously performing the work efficiently by revising the conventional method in which the primary shield work is preceded and the excavation of the enlarged width portion being carried out separately thereafter. SOLUTION: Foundation improvement work is performed in an increased width section, excavation is performed by a shield (M) of the standard diameter, a tail portion is freed and excavated for the enlargement and a shelter (3) is installed, a drive jack (4) is installed to the shelter portion, the shield (4) is driven and excavated with the drive jack (4) simultaneously with the excavation of the increased width section, a segment (6) is assembled in the increased width section for each predetermined drive, the drive and segment assembly are repeated, the drive jack is removed after passing the predetermined increased width section, and the standard diameter shield work is carried out.
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