What Are Bored Piles?
Piling is an ancient technique for supporting the foundations of a structure with long stilts or ‘piles’ which sit vertically underneath a construction. The oldest use of piles can be found in prehistoric piled dwellings in the alps, when ancient humans used piles to lift their homes away from the watery earth in swamps and wetlands. Modern piles are much different, but still use the same principles! Piling can be done in a number of different ways, from driving them into the earth to casting them in place. Today we’ll be looking at bored piles – not that they’re tired and uninterested, but that they are installed by first boring a hole into the earth for the pile to be placed into. Bored piles have a variety of advantages and disadvantages, let’s take a look:
Created from concrete
Bored piles are created from concrete. Unlike driven piles which can be concrete, steel, or even wooden, bored piles are exclusively cast from concrete. This is because it is easier and more effective for pre-made piles to drive or screw them into the ground. Boring a hole first would reduce much of the friction and pressure required to ensure the pile is sturdy and unwavering.
As mentioned above, pre-made (or pre-cast) piles are best used with other installation methods. Bored piles are cast in-situ, which means that the bore hole created is then filled with liquid concrete, along with other reinforcement materials, to allow it to set to form the pile in place. This is also why bored piles are exclusively concrete, as it’s either impossible or wildly impractical to pour liquid wood or molten steel into a bore hole to create a pile.
Can come with permanent or temporary casing
Cast in-situ piles have a few different sub-methods for proper installation. The casing, for example, can be made to be either temporary or permanent. The pile casing is a large steel tube which is placed into the bore hole before the concrete is poured in. A permanent casing is left in place forever to provide a metal covering for the pile and an extra layer of reinforcement. Temporary casings are left in place while the concrete sets and are remove afterwards. Removed casings can be reused or recycled but they can cause lots of noise and vibrations to remove.