Topic 4.1.1 Flashcards
What is a pile foundation
Foundation system that transfers loads to a deeper and competent soil layer
When to use pile foundation
Inadequate bearing capacity of shallow foundations.
To prevent uplift forces.
To reduce excessive settlement.
How can you classify piles
Function
Material
Installation method
Piles classified by function
End-bearing piles
Friction piles
Piles classified by material
Timber
Concrete
Steel
Piles classified by installation method
Displacement/Driven
Replacement/Bored
What is the difference between end-bearing and friction piles
Load bearing resistance of end-bearing piles derives mainly from end-bearing stress at the base of the pile
Load bearing resistance of friction piles derives mainly from skin friction
What is the difference between driven and bored piles
Driven piles are formed by driving precast piles
Bored piles are formed by casting concrete in a hole bored or drilled
Displacement piles that are hollow and have small displacement
Steel pipe
Concrete spun piles
Displacement piles that are solid
Precast R.C. pile
Precast prestressed piles
Steel H-piles
Bakau piles
Treated timber pile
Displacement piles that are driven cast in-place
Concrete tube
Steel tube
Non-displacement piles (replacement)
Bored piles
Micropile
Installation method of piles
Hammers
Jacked/Pushed-in
Boring
Types of hammer installation
Dropping weight/dropping hammer
Steam hammer (Single/double)
Air hammer (Single/double)
Diesel hammer (Single/double)
Hydraulic hammer
Vibratory hammer
Types of boring installation
Auger boring
Grabbing
Wash boring w/ water jets
What is the most common type of deep foundation
Precast concrete piles
What sizes do precast concrete piles come in
150mm-400mm
3m, 6m, 9m, 12m in length
How are precast concrete piles driven
Using drop hammers or vibrators using a piling rig
What is the structural capacity of precast concrete piles
25 tonnes-185 tonnes
Advantages of precast concrete piles
No waste generation on site
Not affected by groundwater
Most economical form of deep foundation
Can be driven underwater
Disadvantages of precast concrete piles
Require heavy pile driving machinery for installation
Pile may break during transport or driving
Length is limited as it depends on transport facilities
Uneconomical to cut the pile if it is too long
Properties of spun piles compared to precast concrete piles
Better bending resistance
Higher axial capacity
Better manufacturing quality
Higher tensile capacity
What sizes do spun piles come in
250mm-1000mm
6m, 9m, 12m in length
What is the structural capacity of spun piles
45 tonnes- 520 tonnes
