Rotary Bored Piling (RBP) is a widely used piling technique for foundations. This technique employs a machine, called a piling rig, with specially designed drilling tools including buckets and augers that remove soil and rock from the ground.
Where the underlying ground conditions are unstable, up to 20m from the surface, a temporary casing is installed by the piling rig. This prevents collapse of the upper unstable ground.
Benefits
Rotary bored piling is a foundation system that transmits high structural loads into lower load bearing soils. It can be used in conjunction with other pile types or as a standalone method of foundation construction.
Bored piles can be installed in contiguous, tangential or secant designs and can be manufactured in a variety of lengths, diameters, materials, geometries and layouts to meet individual project needs. They can also be positioned at different depths to allow for variable ground conditions.
The installation process begins with drilling a vertical hole into the ground using a bored piling machine. The machine is outfitted with specially designed drilling tools, buckets, and grabs to remove the soil and rock.
Installation Method
Rotary bored piling is a method used to create piles for foundation construction. It uses a piling rig with specially designed drilling tools and buckets to bore into the soil repeatedly, removing spoil as it progresses until the design depth is reached.
Bored piling is suitable for a variety of ground conditions and is used on all kinds of sites. It also reduces noise and vibration pollution, making it perfect for urban locations.
When the underlying ground conditions are unstable throughout the length of the pile, a temporary casing may be installed to ensure the bore does not collapse. Alternatively, a fluid support system, such as polymer or bentonite, can be used to maintain the bore.
Bored piles are constructed using a drill or auger that excavates the ground to the required depth before a steel cage or pattern of reinforcing bars is introduced, and concrete is poured into the hole. In some cases, a permanent casing or a combination of casing and fluid support is used.
Ground Conditions
The ground conditions can have a significant impact on the installation of rotary bored piling. The contractor must perform a thorough soil investigation to determine the properties of the ground.
The optimum drilling tooling for a specific soil is then selected and the drill method chosen to excavate the desired diameter and depth of the pile. The bore is then cleaned to the required depth using an auger, bucket or coring unit connected to a telescopic Kelly bar.
The drilled hole is then lined and filled with concrete before the steel cage or pattern of reinforcing bars are added. This method is often used for large commercial and industrial developments, public buildings and transport infrastructure as well as marine projects.
Cost
Rotary bored piling is an increasingly popular piling technique that has many benefits and can be used on a wide range of projects. They are often larger diameter than conventional continuous flight auger (CFA) piles and can be used to support greater loads, overcome underground obstructions or penetrate ground that is too hard for CFA drilling.
The rotary boring piling technique is a highly efficient method of achieving pile bores up to 60m deep and up to 1.8m diameter. This is possible because it uses a machine with specially designed drilling tools, such as buckets and augers to remove soil and rock until the design depth is reached.
A temporary casing is installed to prevent the bore collapsing in unstable ground conditions. In non- cohesive ground, such as made ground and granular layers, this is typically screwed in using the piling rig or vibrated into place by specialist vibrators.
