| 摘要 |
PROBLEM TO BE SOLVED: To enable construction of an underground wall of a large cross section, reduce construction cost, and achieve excellent water stopping performance at connection parts of joints between steel pipe sheet piles by constructing the steel pipe sheet piles of a large bore diameter even when a diameter of a boring casing or the like in a boring machine used in construction is similar to that in conventional ones. SOLUTION: As a preceding process, columnar bodies 14 are formed one by one having an interval between each other without overlapping their end parts using a boring machine provided with a single auger screw which is rotated while discharging hardening liquid such as cement milk from a tip. As a post-process, using boring machine of an enlarged diameter, boring is performed using bored parts of every two or plural columnar bodies 14 provided in the pre-process formed when the columnar bodies 14 are constructed as guides, and steel pipe sheet piles 15 provided with joints 15a, 15b are constructed to bored parts by the diameter-enlarged boring machine. At this time, connection between joints 15a, 15b of the steel pipe sheet piles 15 is conducted in the columnar body 14 positioned between the columnar bodies 14 used as the guides.
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