Pile is elementally a long cylinder of a powerful material such as concrete that is drilled into the ground to act as support for structures constructed on top of it. Pile foundation has a large number of applications as will be described below:
In foundation, the main point of bother is bearing capacity of the soil. Bearing capacity is the maximum load that can be underpinned by the soil layer. When the soil is strong sufficient that it can support the whole load coming on it, then we use a shallow foundation. Shallow foundations are mostly used where the hard soil layer is found at such a depth that the construction of the foundation is cheap.
If hard soil is found at extending far down from the top or surface from levels of earth, then there is a need for any source that can transfer the load of the structures on the deep hard soil layer. This can be used to be a deep foundation. A pile foundation is a type of foundation in which a pile is mostly used as the structure to bear the load to the deep soil layer. Piles are long and lean members that bear the load to hard soil disregard the soil of low bearing capacity. The transfer of load is dependent on the capacity of the pile. The pile should be strong sufficient to transfer the huge load coming on it to a fundamental hard layer of soil. For this purpose, pile design is mostly given much thought. Depending on the load, the type of material is mostly chosen for the piles.
Piles are basically made from below materials:
- Composite pile.
Design Pondering of pile foundation:
Pile is the process for the design of the deep foundation. The first step in the design of the pile foundation is the decision of the right type of pile. Suitable of type, length, & capacity of the pile be dependent on the following boundary:
- Soil condition
- Magnitude of load
Factors Affecting Selection of Piles
Factors that affect the choice of the pile are as follows:
- Length of the pile in relation to load and soil condition
- Behavior of structure
- Availability of material in the locality of construction
- Type of loading
- Ease of maintenance
- Availability of funds
- Factors causing damage
- Cost of piles
Geotechnical design of pile foundation:
By geotechnical design:
- Depth below the ground
The total load supported by the pile and its parts is said to be the ultimate load. It is mostly denoted by ‘Qu’. A load that can be supported by a pile is due to its pole and bearing resistance.
Qu = QS + Qb
Where QS is pole resistance and Qb is bearing resistance
Load Carrying Capacity of Piles
Usually, three methods are used for calculating the capacity of the pile:
- Static formula (this formula is appropriate to operate and in-situ piles)
- Dynamic formula (this formula is appropriate to operate piles)
- Load Test (this test is basically done two times to design load. If it is stable then the pile is considered to be carried out). This test is more expensive and time-consuming. Load supplication is also very much difficult in this test)
More things which have significance in pile foundation design are:
- Pile spacing
- Negative skin friction