| 摘要 |
PROBLEM TO BE SOLVED: To reduce construction cost and shorten the period of time for work when constructing wall body for a large underground cavity by using a shield drive machine having a small cross section. SOLUTION: This shield drive machine is formed into a double structure E for a rear end portion 13a of a drum body 13 having an almost the same dimension as that of a small-diameter cutter with an inner drum body 16 arranged together with an outer drum body 15 with a predetermined clearance f between them; an unit wall body 22 consisting of a segment S is pushed out from the rear of the inner drum body 16, a subsoil improving solution is discharged to the inside of a rear cavity at a stepped portion at the rear end of the double structure E, and a cavity of a small cross section of the double structure consisting of the unit wall body 22 and the improved subsoil at the outer periphery of the unit wall body 22 is formed.
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