PILE TYPES BASED ON CONSTRUCTION METHOD
Three pile types of pile foundations according to their construction methods:
- Driven piles,
- Cast-in-situ piles, and
- Driven and cast-in-situ piles.
1. Driven Pile Foundations:
It is of concrete, steel or timber. These piles are prefabricating before placing at the construction site. If drive piles are of concrete, they are precast. These piles are drive using a pile hammer.
When piles drive into the granular soils, they displace the equal volume of soil. This helps in compaction of soil around the sides of piles and results in the densification of soil. The piles which compact the soil adjacent to it is compaction pile. This compaction of the soil increases its bearing capacity.
Saturated silty soils and cohesive soils have poor drainage capability. So these soils are not compacts when piles are drill through it. The water is to be a drain on the soil to be compact. Stresses develop adjacent to the piles have to be borne by pore water only. This results in an increase in pore water pressure and a decrease in bearing capacity of the soil.
2. Cast-in-situ Pile Foundations:
Cast-in-situ piles are the concrete pile. These piles construct by drilling holes in the ground to the required depth. And then filling the hole with concrete. Reinforcements utilize in the concrete as per the requirements. These piles are of small diameter compare to drill piers.
Cast-in-situ piles are straight bore piles or with one or more bulbs at intervals are cast. The piles with one or more bulbs are under-reamed piles.
3. Driven and Cast-in-situ Piles
Driven and cast-in-situ piles have the advantages of both driven and cast-in-situ piles. The procedure of installing a driven and cast-in-situ pile is as follows:
A steel shell of the diameter of a pile driven into the ground with the aid of a mandrel inserting into the shell. After driving the shell, the mandrel removes and concrete pours into the shell.
The shell is of corrugate and reinforces thin sheet steel or pipes. The piles of this type are shell type piles.
The shell-less type formes by withdrawing the shell while the concrete places. In both the types, the bottom of the shell is close to a conical tip which separates from the shell. By driving the concrete out of the shell an enlarge bulb form in both the types of piles. Th shells left in place and the tube concretes. This type of pile is very much use in piling over water.