Friction piles
Foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics to support them. Very broadly, foundations can be categorised as shallow foundations or deep foundations.
Pile foundations are a type of deep foundation, formed by long, slender, columnar elements typically made from steel or reinforced concrete, or sometimes timber. A foundation is described as 'piled' when its depth is more than three times its breadth.
Pile foundations are principally used to transfer the loads from superstructures, through weak, compressible strata or water onto stronger, more compact, less compressible and stiffer soil or rock at depth. They are typically used for large structures, and in situations where soil may be subject to excessive settlement.
Friction (or floating) piles develop most of the pile-bearing capacity by shear stresses along the sides of the pile, and are suitable where harder layers are too deep to reach economically. The pile transmits the load to surrounding soil by adhesion or friction between the surface of the pile and soil, which in effect lowers the bulb of pressure. In other words, the whole surface of the pile (cylindrical in shape) works to transfer the forces to the soil.
To gain a better understanding, consider a nail that is driven into a piece of timber. The nail becomes more secure and tightly fastened into the timber, the further in that it is driven. The greater the embedment depth in the ground, the more load the pile can support – the load-bearing capacity of the pile is directly proportionate to its length.
Friction piles are in contrast to end-bearing piles which develop most of their load-bearing capacity at the toe of the pile, bearing on a hard layer of rock or very dense soil and gravel.
For more information see: End-bearing piles.
[edit] Find out more
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
A bridge between Scotland and Northern Ireland
What's the verdict from the court of public opinion?
Open plan living falls out of fashion
Shift to home-based work influences closed plan preferences.
The UK heating industry and the Brexit transition
An overview of the current state of the market.
UEFA guide to renovating football training facilities
Organisation offers best practices for construction and modification.
Heritage on the edge?
Prioritising tax considerations.
Reviewing the Double Diamond Design model
The four D creative process: discover, define, develop and deliver.
National Cyber Security Centre initiative is announced.
The impact of COVID-19 on global HVAC&R markets
Reviewing trends and projections.
Legislation will establish initiatives to move towards net zero.
Status determination statement
How to document contractor employment status.
Social distancing goes high tech
Tech tools to help manage people and space post-pandemic.
Eclectic Edwardian architecture
A style that ranges from mock Tudor to arts and crafts to the 'Wrenaissance'.
Free guide from Secured by Design.