| 摘要 |
PROBLEM TO BE SOLVED: To conduct press-in easily even when push-in depth is deepened. SOLUTION: An outer tube 15 is eccentrically installed rotatably onto the outer circumference of the diameter shrinking section 12 of an inner tube 11 having a bit 13 at a front end through plain bearings 14. The pushing-away section of a ground is made wider than the base area of the tube while the increase of earth pressure in the inner tube 11 is inhibited as compared with the earth pressure of soil and sand introduced into the diameter shrinking section 12, resistance working to the outside of the inner tube 11 is lowered and the whole tube is pushed in deeply, and pressing-in is conducted easily even when push-in depth is deepened at that time.
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