No matter which method you use, all piles are similar in their purpose — they transfer a structure’s load to a more stable rock layer beneath the ground. It’s a handy construction method used when a construction site’s surface soil is too loose and unstable to hold the structure.
Back to basics: How does piling work?
Before we go into the different types of piling methods, let’s quickly recap what piles are and how they operate.
What are piles?
Firstly, pile foundations are the columns that work as the base, and a pile is the column that helps transfer the weight of the load to sub-soil (the underground rock layer). They are commonly confused due to their similar names.
Pile foundations are long and thin and can be made from steel, concrete, or timber, with each material having its own benefits. Steel is great for strength and durability, concrete piles are a top choice for heavy loads, and timber piles are affordable and easy to install.
What are the different types of foundation piling?
It’s important to note that some pile foundation types are named after their technique, and some are named after their purpose. For example:
- End-bearing piles: Designed to redirect the structure’s weight to a reliable soil or rock layer beneath the surface. Best for construction areas with weak topsoil.
- Friction piles: Distribute weight via friction between the soil and the surface of the pile. Best for structures built on soft, deep soils.
Different types of piling methods
All piling methods involve the piling foundation being bored or drilled into the ground. Construction teams assess the building site in detail to decide on the most effective and suitable piling method, depending on soil type, the type of structure being built, and other considerations like location, noise levels, and usage.
Driven piling (also known as displacement piling)
Driven piling is also known as displacement piling, as the process involves displacing the soil instead of fully removing it. However, pre-drilling is sometimes required if the soil is quite dense.
Due to the strength and durability of this piling method, it is particularly popular for building bridges and heavy structures.
Depending on the project’s requirements, driven piles are pre-made from steel, concrete, or timber and then driven into the soil using a pile driver — a piece of large, heavy-duty piling equipment.
The installation process
- The site is surveyed, and the pile locations are marked to ensure the best efficiency.
- The pile is positioned in a vertical or inclined position.
- The pile driver drives the pile into the soil until it reaches the desired resistance.
- The construction team carry out pile integrity and dynamic load tests to ensure the required load-bearing capacity.
- The pile is cut and fitted with a cap or plate to then be connected to the structure’s foundations.
Bored piling
Best for large building constructions in built-up areas due to minimal noise and vibration, the bored piling method involves excavating holes into the ground and filling them with concrete.
Some construction teams may use CFA (Continuous Flight Auger) piles, which drill and pour simultaneously using a hollow auger for quicker installation.
The installation process
- The site is surveyed, and the pile locations are marked out.
- A rotary drilling rig creates a borehole in the ground until it reaches the desired depth.
- A steel rebar cage is installed to help reinforce the concrete.
- The casting process begins, where concrete is poured into the borehole.
- The concrete is left to cure before being load tested.
Screw piling (also known as helical piling)
Steel piles have screw-like helical blades, which are then twisted into the ground. They’re ideal temporary structures on soft soils, loose sand, and marshy areas and can be removed and reused.
The installation process
- The site is surveyed, and soil conditions are checked.
- A hydraulic rotary drive is used to twist the screw pile into the soil. The helical blades are handy for creating resistance, resulting in a sturdier and more reliable structure.
- Torque resistance is monitored to determine when the screw pile has reached a suitable soil layer.
- The screw pile is either bolted or welded to a building’s foundation structure or a bracket.
- No curing time required!
Sheet piling
Sheet piles are long, thin sheets — usually made from steel, concrete, or vinyl. They have interlocking edges that create a wall-like structure to reinforce loose soil or water-logged areas. It’s a popular piling method for unstable building sites as the installation involves hydraulic pressing, which is silent and vibration-free.
The installation process
- The location of the sheet piles is marked.
- The first sheet is positioned and driven into place using a hydraulic press.
- The other sheets are positioned and driven in, interlocking with the prior sheets to create a wall.
- The tops of the sheets are aligned.
Micro piling
Designed specifically for building sites with limited access or weak ground conditions, micro piles are much smaller, usually 100-300mm in diameter. For this reason, micro piling is typically used for foundation repairs and retrofits.
The installation process
- A hole is created using a small rotary drill rig.
- A steel rod or rebar cage is inserted into the hole for reinforcement.
- The hole is then filled with grout or concrete.
- The micro pile is then left to cure before load testing.
WL Piling: Your local North West piling contractors
With over 50 years of expertise, our team at WL Piling have been conducting piling services across the North West. We use innovative equipment and cutting-edge technology for the best results, including our innovative air-driven Grundomat piling method.
Leave the excavation, piling, and project management to our reliable and trusted team.
Contact us today — we will be more than happy to assist you with your construction project, no matter how big or small.
