Intro to piling 3-9 October Flashcards
Main use of strip foundations
Transferring long continuous loads such as walls when ground conditions are good
What is the purpose of a foundation?
To transfer load from a structure to the ground safely without causing unacceptable settlement
Name three factors that affect foundation choice
Type, weight/ use of structure, ground/soil conditions
Name the main use of a pad foundation
Underneath point loads such as columns
What is the purpose of rienforced concrete raft foundations?
Spread the load over a whole building area reducing the load per unit area
When are raft foundations used?
when building loads are high and/or ground conditions are poor
How do piles work?
takes the load through weak soil to load bearing strata
What does CFA stand for?
Continuous flight auger
What is step one of CFA construction?
Auger is lowered to the ground to start drilling and is not removed during drilling as it supports the bore sides
What is step two of CFA construction?
Drill to the design depth
What is step three of CFA construction?
Concrete is delivered through the center of the auger to the base of the bore and auger is removed at the same rate as concrete fill, excavated soil is to be disposed of
What is step 4 of CFA construction?
Reinforcement cage is added to the wet conrete
What is an auger?
A tool resembling a large corkscrew used for boring
What are the advantages of CFA?
Quiet
vibration-free
no casing
can be used when rocks are weak
State the disadvantages of CFA
Blind piling
Tolerances
Depth limitation
Obstructions
bore spoil
What classification are CFA piles?
Replacement usupported
What classification are CFA piles?
Install casing and begin drilling through strata layers
When drills reach firm strata at design depth reinforcement cage is lowered into the hole and concrete is poured
What are the steps for rotary bored piling?
Install casing and begin drilling through strata layers
When drill reaches firm strata at correct depth lower reinforcement cage into the hole and pour concrete
Advantages of rotary bored piling
Range of diameters
High load capacity
Ground is seen
Can be used on adverse ground
Rock boring in all rocks
Obstructions are dealt with
Disadvantages of rotary bored piling
Slow
Soil to be disposed of
Expensive
Lots of bore supports needed
What classification is rotary bored piling
Replacement supported
What are the advantages of driven cast in-situ piling?
Rapid installation
Economical
Enhanced based resistance
Deals with obstructions
No spoils
Disadvantages of driven cast in-situ piling?
Noisy
Vibrates a lot
Limited length
What’s is the classification of driven cast in-situ piling?
Displacement driven cast in-situ
What are the advantages of driven precast concrete piles?
Versatile
Economical
Clean site
No spoils
What are the disadvantages of driven precast concrete piles?
Noisy
Lots of vibrations
Waste
Can’t deal with obstructions
What is the classification of driven precast concrete piles?
Displacement preformed concrete
