| 摘要 |
PROBLEM TO BE SOLVED: To improve performance by intermittently installing spiral excavating blades on the front end side of a supporting bar buried into a ground and sharpening the side penetrated into the ground of the excavating blades and the perimeters of the blades. SOLUTION: Outside diameters and spiral pitches are formed in small sizes towards front end sides in spiral excavating blades 10a, 10b, 10c intermittently mounted on the front end side of a supporting bar 1a. Ground penetrating sides (a) and peripheral sides (b) are formed sharply in each blade 10a-10c while spiral pitches are made larger than other sections in the reverse sides (c) in the penetrating direction and the reverse sides (c) are formed in a jumping-up shape. A drill section 20 is set up at the front end of the bar 1a, and a constricting section 30 as an excavated-powder housing space is formed to the upper section of the drill section 20 and penetration into a ground of the drill 20 is assisted. A collar section 40 having a diameter larger than the bar 1a is formed to the lower section of a head section 2, and earth removal is suppressed and the effect of a non-earth removal construction method is improved. Each section is integrally cast by spherical graphite cast iron, and low bentonite-treated and hardness is increased. Accordingly, the underground anchor can be buried easily even to the hard ground by small revolving torque, and can be manufactured at a low cost.
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