Ground Anchor

Abstract

A ground anchor (10) comprising an anchor shaft (11) and an anchoring screw (13) moulded onto the anchoring shaft adjacent the lower end thereof. The anchoring shaft (11) is of a rectangular cross-section with four side walls (12). The anchoring shaft (11) is configured at its bottom end (15) for ground penetration. The upper end (19) of the anchor shaft (11) is configured to receive torque applied thereto. The anchoring screw (13) comprises a hub (21) and a screw flight (23) on the hub. The anchoring screw (13) is moulded onto the anchor shaft (11), and the hub (21) is keyed to the anchor shaft. The anchoring screw (13) is so constructed that the spiral flight (23) is rigid yet has some resilient flexibility which allows the flight to deflect laterally in the direction of the screw axis. Specifically, the screw flight (23) has sufficient rigidity to allow it to penetrate the ground in which it is intended to be used when torque is applied to the anchor shaft (11). Further, the screw flight (23) has sufficient rigidity in order to retain the ground anchor (10) embedded in the ground when subjected to the normal load conditions for which it is intended, as is the case with conventional ground anchors. The resilient flexibility provides the screw flight (23) with a degree of ‘springiness’, so allowing the screw flight (23) to deflect laterally in the direction of the screw axis when subjected to the loadings to which it is exposed when winding into the ground. With this arrangement, the pitch of the helical screw (25) is permitted to alter during ground embedment as ground pressure increases.

Description

FIELD OF THE INVENTION[0001]The present invention relates to ground anchors, and more particularly to ground anchors employing an anchoring screw to embed the anchor into the ground. Ground anchors are also often referred to as earth anchors.BACKGROUND[0002]Anchors installed in soil are commonly utilised to provide support, either in tension or in compression, and provide support or a tie down point for various equipment and structures. For example, ground anchors are commonly utilised to provide anchorage, in tension, for guy lines used to support electrical transmission equipment. They can also be used to provide a stable surface upon which equipment can be mounted. When this is done, the top of the anchor is normally encased in concrete to provide lateral (ie side to side) stability and the equipment is mounted thereupon.[0003]Ground anchors typically include a helix formed in a spiral configuration around a hub. The helix is rigid and most commonly of metal. Some designs have us...

AI Technical Summary

Benefits of technology

[0014]With this arrangement, the rigid nature of the screw flight allows it to move through the ground during rotation while also allowing some lateral deflection in response to loading on the screw flight to change the pitch of the flight.

[0033]Furthermore, it has been found that flexibility provided by the flexible helical shape material behaves as a shock absorber in cyclic tensile load conditions, reducing the snatch effect upon connections to the ground anchor (such as connecting tendons or guy wires).

Problems solved by technology

Therefore the ability of the ground anchor to resist lateral loads (ie transverse to the longitudinal direction of the anchor shaft) is limited in comparison to the ground holding ability of the helical screw.

Such in-situ stabilisation is time consuming and labour and material intensive.

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