Precast Piles – What You Need to Know

• Rig delivery into site and setup process, to include permit signature, site inspection, platform inspection, internal induction.
• Pile delivery arrival and wagons entering site and sighted next to rig
• Pile unloading, this includes from pile delivery and laying piles down on floor beside pile pin positions. Rig used as a crane for this purpose, you could include methods of unloading on wagons with edge protection etc
• Pitching piles, lifting from the floor with the hammer line and offering piles into the helmet, then aligning pile over the pile position and ensuring the verticality in x and y
• Driving piles, and levelling carrying out lift offs to check position as you go including jointing if required and taking final 3 sets
• Testing of pile

The fundamental difference between a driven pile foundation and bored pile foundation lies in their point of manufacture. A driven pile is formed off-site under factory-controlled conditions and a bored pile is manufactured on site and in place.

Bored pile foundations, also known as replacement piles, are typically poured in place and provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics. Driven piles are sometimes referred to as displacement piles because in the process of driving the pile into the ground, soil is moved radially as the pile shaft enters the ground. There may also be a component of movement of the soil in the vertical direction.

1.  Piles can be precast to the required specifications.
2.  Piles of various size, length, and shape can be made in advance and used at the site. As a result, the progress of the work will be rapid.
3.  A pile driven into granular soil compacts the adjacent soil mass and as a result, the bearing capacity of the pile is increased.
4.  The work is neat and clean and creates no spoil arisings. The supervision of work at the site can be reduced to a minimum. The storage space required is very much less.
5.  Driven piles may conveniently be used in places where it is advisable not to drill holes for fear of meeting groundwater under pressure.
6.  Driven piles are the most favoured for works over water such as piles in wharf structures or jetties.
7.  Driven piles maintain their shape during installation. They do not bulge in soft ground conditions and are typically not susceptible to damage from the installation of subsequent piles.
8.  Driven piles require no curing time and can be driven in natural sequence rather than skipping alternate piles, thus minimising the moving of the equipment and speeding up installation time.
9.  The equipment and installation methods are time-tested and well proven. Advances in materials, equipment, methods, and testing continually combine to improve the efficiency of driven piles.
10. Fewer traffic movements are required to and from a site when compared to alternate piling methods.

Curing precast concrete in the correct environment is essential to longevity of life. Aarsleff install Centrum Piles – cast in-house by our sister company, Centrum Pile. Centrum piles are cured in a factory coded to ISO 9001 and are all certified to BS EN 12794. Quality is of upmost importance and is monitored for every pile, with full traceability built into the Centrum Pile System. This quality assurance combined with Aarsleff’s delivery expertise means that you can be assured of the quality of your solution.

With the benefit of using pile joints, precast concrete piles can be driven to lengths longer than 30m. Often concrete precast piles can be driven down to 30m, however, in special circumstances, such as offshore projects, piles can be driven down to a maximum of 150m.

There is no established depth for foundations; nor is there a simple way of determining suitable depths. Instead, there is a very wide range of foundation types and depths suitable for different applications, depending on considerations, such as:

• The nature of the load requiring support
• Ground conditions
• The presence of water
• Space availability
• Accessibility
• Sensitivity to noise and vibration

Shallow foundations are suitable at a depth of around <2.5 m, any deeper and you would need to look at a suitable piling solution. If the foundations are to be in close proximity to an adjacent structure, care must be taken to ensure the excavation works do not undermine it, nor is additional pressure exerted upon it. The foundation may need to be at least the same depth as the adjacent building’s foundation base.