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What is the pile foundation?

The pile is a structural member that is made of either concrete, timber or steel. It is a small diameter column, which is driven or cast into the ground up to suitable depth. They are used to construct a foundation, which is deep and of course which cost more than shallow foundations. 

Pile foundation is used when the soil immediately below the foundation can not safely support the loads and load has to the transferred deep into the underlying soil. It is required when the soil-bearing capacity of the soil is not sufficient for the structure. The main function of the pile is to transmit loads to the lower level of the ground by the combination of friction pile and end-bearing pile at the pile point or base.



The Pile foundation consists of two major components: a Pile cap and a single pile/group of piles. Pile cap supports the single column or group of columns. Piles transfer the loads from the structures to the hard strata.

We use a pile foundation when –

A pile is a long slender foundation member, made of either timber, structural steel or concrete, which might be cast-in-situ, or driven and acts as a structural member to transfer the load of the structure to a required depth in deep foundations carrying a load which may be vertical or lateral or lateral plus vertical

Uses of Piles –

As far as deep foundations are concerned there are no. types of deep foundations and pile foundation is among one of them; uses of Pile Foundation depends on the type of pile used, the intended function for which the pile is used, the load which is to be applied on the pile and the type of material which is used for the construction of the pile.

The uses of piles are –

  1. End Bearing or Compressive Strength

    Sometimes we use the piles to achieve the required compressive strength in the soft soil; in that case, we use the piles to transfer the load through that soft soil to a suitable bearing stratum by using the end bearing or toe bearing property of the pile

  2. Scour Depth:

    To build a structure within the water and on the water river or canal bed; we have to build the foundation through the riverbed and within the scour depth.

  3. Tension or Uplift:

    Piles are usually used to carry the compressive load through tip bearing or end bearing, but in the case of tall structures or towers there might be tension that must be resisted by piles. For example, for a tower carrying high power transmission lines the thrust of wind might produce overturning that must be resisted by the tension piles; other options include the use of a deep foundation or thick raft, which is sometimes uneconomical.

The pile may be classified as long or short in accordance with the L/d ratio of the pile (Where, L= length, d = diameter of the pile). A short pile behaves as a rigid body and rotates as a unit under lateral loads. The load transferred to the tip of the pile bears a significant proportion of the total vertical load on the top. In the case of a long pile, the length beyond a particular depth loses its significance under lateral loads, but when subjected to vertical load, the frictional load on the sides of the pile bears a significant part to the total load.

The pile may further be classified as vertical piles or inclined piles. Vertical piles are normally used to carry mainly vertical loads and very little lateral load. When piles are inclined at an angle to the vertical, they are called batter piles or raker piles. Batter piles are quite effective for taking lateral loads, but when used in groups, they also can take vertical.


According to the method of construction, there are three types of piles. They are

Driven piles,

They may be driven either vertically or at an angle to the vertical. Piles are driven using a pile hammer. When a pile is driven into granular soil, the soil so displaced, equal to the volume of the driven pile, compacts the soil around the sides since the displaced soil particles enter the soil spaces of the adjacent mass, which leads to the densification of the mass. The pile that compacts the soil adjacent to it is sometimes called a compaction pile. The compaction of the soil mass around a pile increases its bearing capacity. If a pile is driven into saturated.

If a pile is driven into saturated silty or cohesive soil, the soil around the pile cannot be densified because of its poor drainage qualities. The displaced soil particles cannot enter the void space unless the water in the pores is pushed out. The stresses developed in the soil mass adjacent to the pile due to the driving of the pile have to be borne by the pore water only. This results in the development of pore water pressure and a consequent decrease in the bearing capacity of the soil. The soil adjacent to the piles is remoulded and loses to a certain extent its structural strength. The immediate effect of driving a pile in soil with poor drainage qualities is, therefore, to decrease its bearing strength. However, with the passage of time, the remoulded soil regains part of its lost strength due to the reorientation of the disturbed particles (which is termed thixotropy) and due to consolidation of the mass.

The advantages and disadvantages of driven piles are:



What is meant by Pile Foundation?

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