| 摘要 |
An anchor assembly for securing a boring machine to the earth is provided. The anchor assembly includes a shaft equipped with a helical assembly by which the shaft can be driven into and removed from the earth like a screw. The helical assembly preferably includes a plurality of flights and a plurality of wings pivotally attached to the flights and helically aligned therewith. The wings and flights are configured so that rotation in one direction urges the wings into the retracted position. However, counter-rotation for only part of a turn forces the wings into the extended position, which expands the diameter of the helical assembly. Thus, the extended wings bite into soil that was undisturbed during the initial insertion, providing increased frictional engagement between the anchor and the soil. Yet, because the wings are helically aligned with the flights, the extended wings do not substantially resist withdrawal of the anchor assembly from soil by reverse rotation. The anchor assembly includes a cap assembly with a cylindrical skirt that engages the surface of the earth around the anchor insertion point. A lock nut presses the skirt into the ground clamping the soil between the plate and the helical assembly giving even greater strength to the engagement between the anchor assembly and the earth. The large vertical surface area provided by the skirt, in conjunction with the "ground-clamping" action of the cap assembly, aids in restricting lateral movement of the boring machine and resisting premature displacement of the anchors.
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