Screw piles

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Screw piles, sometimes referred to as screw-piles, screw piers, screw anchors, screw foundations, ground screws, helical piles, helical piers, or helical anchors are a steel screw-in piling and ground anchoring system used for building deep foundations. Screw piles are typically manufactured from high-strength steel^[1] using varying sizes of tubular hollow sections with helical flights.

The pile shaft transfers a structure's load into the pile. Helical steel plates are welded to the pile shaft to suit the site specific ground conditions. Helices can be press-formed to a specified pitch or simply consist of flat plates welded at a specified pitch to the pile's shaft. The number of helices, their diameters and position on the pile shaft as well as steel plate thickness are all determined by a combination of:

1. The combined structure design load requirement
2. The geotechnical parameters
3. Environmental corrosion parameters
4. The minimum design life of the structure being supported or restrained.

Screw pile steel shaft sections are subjected to design parameters and building codes standards for the region of manufacture.

The helices that are welded over the steel shaft are also called "helical flights" or just "flights", and can vary in size depending on soil conditions.

There are a few differences between helical anchors, helical piles and helical piers, although the terms are often used interchangeably. Helical anchors consist of an extendable steel shaft with helical bearing plates. Piles or piers refer to strong base elements that withstand or transfer vertical/horizontal loads. Anchors are piles utilised only in tension applications like restraining wall tiebacks or vertical ground anchors made to resist overturning forces.