Pile foundation is a type of a deep foundation, where the spread foundation is also used but where the hard strata is laying deep beneath pile foundation is used.
Conditions that Require Piles
- Upper layer high compressible too weak to support the load of super structure.
- To horizontal forces pile resist by bending
- Pile resist uplift forces due to water
- Piles can be used in collapsible soil like losses uptill the deep solid rock.
Types Of Pile Foundation:-
Based on materials
- Steel Piles
Pipe piles or rolled steel hollow pole wide flange (I-Sec), where H-Sec is preferred due to web flange equal thickness.
- Concrete Piles
Two types of concrete piles are used which may or may not be further divided
i. Cast Insitu
Steel casing when reached to desire depth is filled by concrete.
With/without pedestal casing is also there but removal after casting
The piles which are made in the factories and then brought to the site are called pre-castted piles.
- Timber Piles
Length of pile sleeve should be five times dia of the pile, in marine area can destroyed by different organisms.
Allowable load carrying capacity
Qall = Ap x fw
Ap = avg area of x section of pile.