| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of absolute inability in pulling out an existing pile or the like large in diameter and long-sized (long depth) exceeding a certain limit, using a large-diameter casing in a conventional pulling-out method. SOLUTION: The ground 1 around the existing pile 2 or the like is bored by the rotating advance of the casing 4. At the same time, muddy water a of set specific gravity in a sedimentation basin (tank) 12 is fed into the casing by a water pump 11 and filled into a gap 10 formed between the inner peripheral surface of the casing and the existing pile or the like or the surrounding ground 1a by inner surface tips 8. The muddy water a coming around from under boring tips 3 provided at the lower end of the casing is filled into a gap formed between the outer peripheral surface of the casing and the ground by the boring tips 3, and delivered to the ground surface together with bored soil and returned to the sedimentation basin (tank). After gravel, debris, and the like under muddy soil are deposited and eliminated in the sedimentation basin (tank), muddy water of the set specific gravity is fed again into the casing by the water pump for circulation.
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