Piling in Australia is the installation of vertical columns in the ground to provide the foundation of a structure situations where the ground is unreliable as a base for specific structures, such as bridges or buildings. These situations include where the ground is too soft, can be washed away, compressed easily, exposed to excessive moisture, or otherwise unsuitable to support a certain amount of weight. In these scenarios, piling is used to stabilise and strengthen foundations, by transferring the load of the structure, and horizontal and vertical forces to solid ground deep beneath the surface.
Piling in Australia is often used for many different projects. A structural engineer will inspect the construction site and determine the necessary foundation. Geotechnical engineers will carry out soil tests that can indicate the capacity for the soil to hold a structure. In the soil test, the water content, corrosive properties, salinity, and several other key factors will help build a profile for the site. All of this information is compiled into a soil report.
After the soil report is completed, the engineers working on the project will need to decide the foundation recommendation, which, if required will include the type, size and material of the piles used. Piling in Australia is an integral part of most construction projects as they’ll help keep the structure secure and suitable for use over many years. The soil conditions in Australia typically require most structures to have strong foundations. Prior to construction check with your Engineer whether you need to consider pilling foundations to transfer the load to the ground to extend the lifespan of the structure.
Types of foundation piling in Australia
The types of foundation piling in Australia, are grouped as either Displacement or Replacement types and are classified based on materials, function, and installation process. Displacement type piles are driven into the ground using a pneumatic hammer or screwed into the ground using a pile driver. Replacement types are where the hole is bored out and filled with reinforcing and concrete.
Load bearing piles transfer the forces to the ground by two different methods. The end bearing pile sits on a hard rock surface below the ground and is able to transfer the load to the solid strata. Whereas a Friction Pile relies on the surface friction between the pile and the surrounding material to carry the load, that is there is no solid rock base that the pile ‘sits’ on.
The site geotechnical characteristics, proximity of nearby buildings, waterways and the purpose of the foundation need to be considered when designing the right foundation for your project.
- End Bearing Piles
- Friction Piles
- Sheet Piles
Materials or construction process
- Timber Piles
- Cast-in-Place Concrete
- Precast Concrete
- Steel Piles
Foundation piling based on function or use
Sheet piles are commonly used when there is loose soil or issues around flowing water, and they’re not used for the vertical support in a structure. Common uses for sheet piling include:
River bank protection
Construction of temporary cofferdams
Retention of loose soil in trenches
Load Bearing Piles
Load bearing piles are designed to transfer vertical loads. These foundations will transfer the weight of a structure through to a layer of soil capable of bearing the heavy load. Load-bearing piles can be further classified depending on how they transfer the weight; these include end bearing, friction, or soil compaction.
End Bearing Piles
End Bearing Piles are load bearing piles where the bottom end will rest on a layer of rock or a strong layer of soil. In this situation, the pile acts as a column where it will transfer the load to the stronger layer at the bottom of the piling.
A friction pile is a load-bearing pile that uses friction to transfer the load to the surrounding soils. Unlike end-bearing piles, friction piles will use the entire surface of the pile to transfer the structure load into the soil.
Foundation piling based on materials and construction process
Piles can be classified into two categories: displacement and non-displacement (or replacement). Piles that will cause soil to be displaced vertically or radially as installed are known as displacement piles. The soil is removed with non-displacement or replacement piles, and the piles are installed into the holes, and filled with reinforcing and poured concrete..
Pre-cast Concrete Piles
Pre-cast concrete piles are manufactured from the construction site and transported when required. Precast piles are reinforced with steel reinforcing bar and can be prestressed to increase the load capacity. . There are more quality control measures with precast piling in Australia, and once a design is established and the formwork in place, identical piles, are easily created.
There are many advantages of precast concrete piling, including resistance to biological and chemical cracks, a high-quality finish, and can be made with a hollow core to aid in driving. As precast piles are made off-site and delivered when required, installation is fast, and an inspection can be carried out before they are installed, improving quality controls. Precast piling can be driven underwater, making them ideal for bridges and piers.
Steel piles are usually made from a hollow pipe or I-section and are can be filled with concrete for additional strength. As steel piles have a small surface area, they are easier to drive than other piles and are mainly used as end-bearing piles. Steel piles are easy to install, can reach greater depths than other piles, and carry heavy loads. The disadvantages of steel piles include being comparatively expensive, and they can deviate while driving.
Timber piles are often used around water, and they’ll last for about thirty years with the proper maintenance. These piles are usually circular, but they can also be rectangular. The length of the pile is usually twenty times its width. Timber piles can support up to 20 tons of weight, and strength can be added by installing specialised plates.
Timber piling is economical, easy to install, durable, and can be cut to specified lengths after installation. Timber piles can also be replaced easily if they are damaged. However, specific lengths of timber piles are not always available, and they can be challenging to install in certain situations. Timber piles are not suitable for use as end-bearing piles.
This piling is installed by using a steel shell which is driven into the ground, and then it is filled with concrete. The steel shell can be removed after the concrete has cured, or it can be left in the ground for additional support.
The shells used on the piles are lightweight, making them easy to transport, and it is impossible to damage the piling before they are installed. Cast-in-place piles require extra supervision to ensure quality, and materials require on-site storage, which can add to costs. Also, the bottom section of the pile may not be symmetrical, which can lead to a reduction in strength; high water flow can impede the construction of this piling process.
** Need something about bored piles
Which piling options are suitable for your project?
At NVC Precast, we can design and create precast piling in Australia that is suited for most projects. Your structural engineer can work with our team to ensure you receive piling that can provide the right amount of strength and support as required for your project. Call our team today to discuss what you need and how we can provide a solution for you.
Also read our previous article.