| 摘要 |
PROBLEM TO BE SOLVED: To prevent the contamination of waters by executing the boring while keeping the water level inside of a core tube at a low position low in comparison with the water lever outside of the core tube by pumping up the water stagnated inside of the core tube. SOLUTION: A lower end of a core boring device 1 is mounted corresponding to a position to be bored of a core C in reinforced concrete slab 8. A pump P is actuated to discharge the water stored in a core tube 2 to the external through a pipe 4, and the water level WL 1 inside of the core tube 2 is lowered in comparison with the water level WL 2 outside of the core tube 2 to generate the predetermined differenceδh in water level. Further the core tube 2 and a drill bit 3 are downwardly moved while rotated by a driving device, and pressed to the slab 8 to bore the slab 8 to form a bored hole 9 having the ring-shape in a plane view. As the diffusion of chips can be easily prevented, the contamination of waters can be easily prevented.
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