Friction Piles In Construction

Friction piles are a type of pile foundation that gains bearing capacity to support the super-structure by the skin shear stresses (frictional resistance force) created along the sides of the piles with the adjacent soil. These transmits the load from the above soil and structure to the soil below by adhesion or friction, as shown in the fig.1 below.

Unlike end-bearing pile, friction piles do not depend on a hard underlayer of soil. Hence, friction piles are used in instances where the hard underlaying strata are too deep to reach. As they do not rest on a hard layer and stays free, they are also called as floating piles.

Skin Friction in Friction piles

Skin friction are stresses created due to the adhesion or friction condition between the pile surface and the surrounding soil. This friction or adhesion created reduce the bulb pressure on the pile surface letting the complete pile surface to act effectively to resist the load. For friction piles, a cylindrical shaped pressure zone is formed around the pile surface. 

Note: Bulb of pressure gives an indication of the depth of the soil that is affected by the footing. 

The frictional resistance force that is developed by the friction pile is depended on the subsoil strata condition. 

Applications of Friction Piles

As mentioned in the definition, friction piles are used where hard strata are too deep to encounter and it is an uneconomical option to go for load bearing piles. It is used in areas where to a great depth , sandy soil exist and where long-end bearing piles are too expensive.

In the construction skyscrapers located in UAE - The world tallest building Burj Khalifa lies over friction piles that is installed over a group of friction piles.

Also Read

Classification of Piles Based on Function and Design

Foundation in Building Construction - Purpose, Features

7 Types of Shallow Foundations in Building Construction