Why is Piling Needed?
Published: 28th September 2016.
Used mainly in the construction of commercial and industrial buildings, piling helps to provide support to new structures when the soil near the surface is simply too weak to support the load in question or when the structures are so massive that extra foundational support is needed regardless of local soil conditions. There are several different types of piles, which may be classified by load transfer mechanism, installation techniques, and the materials from which they are made. In this article, we will take a brief look at some of the types most commonly used in modern construction projects and see how they are able to provide the necessary support for the structures built on top of them. Piles are used in conjunction with pile caps designed for specific applications.
There are two different mechanisms by which piles can transfer the load of a structure to the soil underneath it or to the bedrock that is present at a deeper level. In most real-life cases, both mechanisms are utilised to a lesser or greater degree:
- End Bearing Piles – Also known as point bearing piles, this type of piling is designed to transfer the load to a firm stratum (bedrock) some distance below the surface. They are called end bearing piles because the majority of the support they provide is derived from the resistance of the soil or bedrock to penetration at the end, or toe, of each pile. Some of the support they provide is derived from the friction of the soil against the pile shafts, as with the type of piles described below.
- Friction Piles – For sites with particularly poor soil conditions or where a firm stratum is not present at a usable depth, friction piles may be used. The load bearing capacity of this type of piling comes mainly from the friction, or resistance, of the surrounding soil to the side of the piles. In reality, as mentioned above, friction piling also derives some of its load bearing capacity from the toe of each pile, in common with end bearing piling.
Another common way in which piling is classified is by the way in which it is installed. There are three main methods that are commonly employed:
- Driven Piles – This type is, as you would imagine, driven into the soil. They are prefabricated and driven into place once they arrive on site. Driven piles may be fabricated from steel, concrete or timber.
- Screw Piles – Manufactured from hollow sections of steel tubing with helices attached to the outside of the shaft, near the toe, screw piles are wound into the ground. The helices and shafts can be custom made to suit a wide variety of different soil conditions.
- Bored Piles – Bored piling is installed by first boring holes in the required positions, before pouring reinforced concrete into the boreholes. If the boring and pouring is accomplished simultaneously, they are known as continuous flight augured piles.
If you have any questions about piling or you would like to discuss your needs for a specific project, please do not hesitate to call us during business hours.