| 摘要 |
PROBLEM TO BE SOLVED: To increase the ratio of a purification and improvement body to a diameter of a preceding hole, and reduce a circular soft loosened part of the preceding hole which is exposed on a ground surface. SOLUTION: This excavating device is equipped with paired brackets which are arranged so as to face each other in the axial direction of an excavating rod, and paired agitating blades which are attached to the brackets so as to be oscillated in the direction of the excavating rod in the normal rotation of the excavating rod and oscillated in the direction of being separated from the excavating rod in the reverse rotation of the excavating rod. The paired agitating blades are composed of arc-shaped reinforcing plates, shaft parts which are provided in one-side parts of the reinforcing plates and journaled to the brackets, tip bits which are provided in the other-side parts of the reinforcing plates, and bits which are provided in inside parts of the reinforcing plates. In the normal rotation of the excavating rod, the agitating blade and a tip part of the bracket are housed in a circle which is formed by boring a hole with an excavating head. In the reverse rotation of the excavating rod, both the tip bits are located in the diametral direction of the excavating rod, and a distance between both the tip bits is at least twice as long as a distance between both the bits of the brackets. COPYRIGHT: (C)2004,JPO
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