Helical foundations

[edit] Introduction

There are a number of reasons that helical piles are used in both residential and commercial applications. Their history dates back to the early 1800's. Alexander Mitchell invented the first helical pile in 1833, a feat that earned him a Telford Medal. It is interesting to note that Mitchell was blind at the time that he invented the helical pile and had only four years of formal education.

[edit] The physical attributes of a helical pile

Helical piles are made of secured steel with low-fitted steel plates welded to the base. They resemble household screws used for DIY projects, but on a much larger scale. Tension and compression allow helical piles to stabilise objects in a variety of soil conditions. Machine mounted hydraulic or electrically powered drills are used to install helical piles.

[edit] The progression of helical piling

Since their invention, they have been used for highway foundations, buildings and marine piers. This includes the lighthouse in the Thames Estuary and the 1863 Brighton Pier. Years later, the helical piling technique was utilised for the installation of telecommunication towers. Since the year 2000, it has gradually been adopted as a foundation solution by Network Rail and Highways England.

[edit] The benefits of installing helical piles

There are several benefits of using helical piles:

• They can be installed in confined spaces that are difficult to access.
• They utilise a low-noise, minimal vibration installation method. This prevents disruption to neighbours and protects the existing landscape from damage.
• They can be used to repair existing foundations or for building entirely new ones.
• The equipment used to install helical piles is often smaller and less expensive than other piling techniques.
• They can be installed at any time of year and removed easily and quickly. For example, during the 2012 Olympics, approximately 20,000 seats were installed and uninstalled using helical screw piles. They were then able to be recycled, which would not be possible for concrete foundations.

Helical piles are installed for a variety of new foundations, as well as for a large number of remedial applications such as underpinning or structural slab support.

[edit] Related articles on Designing Buildings Wiki

• Foundations.
• Geothermal pile foundations.
• Pad foundation.
• Pile foundations.

[edit] External references

• The Federation of Piling Specialists.
• Screw Pile Foundations.