Featured Project

Instant Screw Piling was contracted for design services only. The screw pile anchors had to hold the face of the excavation beyond the slip circle.

A technique was devised using four 6-metre benches, excavating from the top down and anchoring, before proceeding with the next bench.

Click here to read the full case study.

Technical Design

Classical formulae are used in the design of Instant Screw Piles. The steel shaft is designed much like a steel column and the helix is designed using standard piling formulaeconsidering the prevailing geotechnical conditions. Some effect of friction on the pile shaft may be considered.

Design Criteria

Design Standards


In Australia, the following standards are relevant to Piling works:
AS 2159-1995 Piling-design and Installation
AS 4100 Steel Structures
AS 3600 Concrete Structures
The Building Code of Australia

Loads


Axial compressive loads of 250 tonne can be achieved using a single pile. Loads can be compressive and/or tension. Piles can be grouped for larger loads and to reduce the effects ofbending moments and eccentric loading.

Slenderness Ratio, Le/r


Pile effective length should be designed after consideration of the geotechnical conditions. Additional helices can be used to reduce the slenderness ratio of the pile.

Geotechnical conditions


Piling design should be preceeded by a through geotechnical investigation report. The report should include results and recommendations of founding level and strength characteristicsof the strata.

Surface Finish


Piles can be installed with a range of surface finishes to suit the design requirements. Such finishes can be mill finish, galvanised, anodised and epoxy painted.Corrosion


Each construction site should be assessed to determine the corrosivity of the prevailing soils. The Australian piling code, AS 2159-1995 has various requirements with respect to corrosion of steel piles. Testing to be carried out include resistivity testing , acidity and chloride assessment. Corrosion may also be addressed using sacrificial anodes and electric anodes.

Connections


Where piles are longer than the maximum length available, a connection may be required to join piles on the construction site. Connections can be welded or bolted depending on circumstances.