An insufficient bearing capacity of the soil to bear a structure will demand for pile foundation. The pile foundation will be chosen based on the:
- Soil Condition
- Types of Loads acting on the foundation
- The bottom layers of the soil
- The site conditions
- Operational Conditions
The pile foundation consists of pile cap and piles either present in single or in groups. The loads coming from the superstructure is transferred safely to the hard strata, soil, and rocks below by means of piles. Piles are long slender members that can have a length of more than 15m.
There are many functions provided by the pile foundation that result in its tremendous applications in construction. Here, we will discuss the necessity and the functions of pile foundation.
When and Where Pile Foundations are Used?
There are certain construction sites that can only go for a pile foundation because it exclusively satisfies certain needs. Some of these needs are mentioned below.
- Pile foundation is needed in areas where the structures constructed are large & heavy and the soil underlying is weak.
- In areas where settlement issues are common due to soil liquefaction or water table issues, pile foundation is a better choice.
- In some situtations, the sub-soil water table at the site will be so high that the use of other foundation will be affected badly. In such a situation, pile foundations can be easily penetrated through the water and extended until a hard stratum is reached.
- Structures might be subjected to horizontal forces that will bring effect to the foundation. The use of pile foundation help in resisting this bending action along with supporting the vertical load coming over the foundation. Hence pile foundation is needed for the construction of earth water retaining structures and building structures highly subjected to lateral (earthquake and wind) forces.
- The pile foundation is necessary to resist the uplift forces created due to water table rise or any other cause. Uplift forces are more common in the construction of transmission towers and off-shore platforms. These structures will need pile foundations.
- Pile foundation is necessary for areas where the structure surrounding has chances for soil erosion. This might not be resisted by the shallow foundations.
- When the plan of the structure is not regular the load distribution also will not be uniform in nature. Employing a shallow foundation in these cases will result in the differential settlement. In order to eliminate differential settlement in such cases, the pile foundation becomes necessary.
- Pile foundation is needed near deep drainage and canal lines.
- The adjacent soil can be confined by means of sheet pile foundation as shown in figure-2 below.
Functions of Pile Foundation
The main functions of the pile foundation in the construction of structures are enlisted below.
- The principal function of the pile foundation is to transmit the loads coming over it safely to the ground. The transmission is performed whether it is vertical or horizontal or inclined loads.
- The pile foundation can be constructed in cohesionless soil by undergoing techniques of displacement and vibration methods.
- Pile foundation helps in reducing the settlement.
- The pile foundation helps to increase the factor of safety of heavy load structures or buildings.
- The pile foundation guarantees the vertical structures above with safety, security, and reliability.
- The pile and pile cap arrangement in pile foundation help the load distribution to be performed in a uniform manner.