Flashcards in deep foundations Deck (5)
what are deep foundations
Typically referred to when the foundations are deeper than 3meters below ground level.
The most common form of foundation is various forms of piled foundations.
There are other types including deep pad or deep strip foundations.
2 main types of pile include
Displacement Piles (Large and small displacement piles)
explain displacement pilling
In simple terms during the displacement pilling method, piles are driven into the ground pushing the ground out of the way, as you see in sheet piling.
Displacement pilling is good for contaminated sites where it can cost a lot to remove soil
Piles are forced into the ground by forcing or driving a solid pile or hollow casting into the ground.
Methods of installation can include drop hammer, vibration or using a jack.
explain replacment pilling
Using the replacement pilling method, soil is removed and replaced with the pile, therefore allowing for larger piles to be used.
The holes are bored either using a hollow weighted grab which is dropped and raised, removing soil as it does or using a rotary borer or auger.
A chemical such as bentonite is used to prevent the sides from collapsing or a shell made of steel is inserted into the hole
This method is quieter than the displacement method and should not result in damage to surrounding buildings.