Monday, May 25, 2015
Types of pile foundations and their usages
There exist three types of construction piles foundations which range from driven piles, Cast-in-situ piles and Driven and cast-in-situ piles.
Driven Pile Foundations: Driven pile foundations are formed with concrete, steel or timber. These piles have to pass through prefabrication process prior to set up at the construction site. Driven piles are known as concrete when these are created with concrete. These piles are possessed through a pile hammer.
When driven piles are consumed with the granular soils, the correspond volume of soil is dislocated. This allows shrinkage of soil all over the sides of piles as well as the compression of soil. The piles which condense the soil alongside, it is known as compaction pile. This compression of soil enhances its bearing capability.
Saturated silty soils and cohesive soils contain inferior drainage capacity. As a result, these soils are not compressed once driven piles are drilled over it. The water must be discharged for the soil chosen to be compressed. So stresses are expanded beside the piles and must be transmitted through pore water only. The outcome will be enhancing the pore water pressure and reducing the bearing capability of the soil.
Cast-in-situ Pile Foundations: Cast-in-situ piles refer to concrete pile. These piles are created with drilling holes in the ground following the necessary depth and then the hole is filled up with concrete. If required, reinforcements are also utilized in the concrete. These piles consist of small diameter correspond to drilled piers.
Cast-in-situ piles denote straight bored piles or having one or more bulbs at intervals which have to be casted. The piles having one or more bulbs are recognized as under-reamed piles.
Driven and Cast-in-situ Piles: Driven and cast-in-situ piles provide same benefits provided by both driven and cast-in-situ piles. The process for setting up a driven and cast-in-situ pile is given below :-
A steel shell of diameter of pile is driven into the ground through a mandrel placed into the shell. Once the shell is driven, the mandrel is separated and concrete is discharged in the shell.
The shell is formed with corrugated and reinforced lean sheet steel (mono-tube piles) or pipes (Armco welded pipes or common seamless pipes). These types of piles are described as the shell type piles.
To form the shell-less type, the shell is removed once the concrete is arranged. Considering both the types of piles, the bottom of the shell is locked by a conical tip that can be disconnected from the shell. A broaden bulb may be created in both types of piles by driving the concrete beyond the shell. Franki piles belong to this type. Sometimes, the shell will be remained in place and the tube is concreted. The extensive use of this type of pile can be found in piling over water.