Rotary Bored Piles are used across all sectors of the construction industry from large commercial and industrial developments to infrastructure projects like HS2 to residential developments, large basements, retaining walls to marine projects.
Bored piles are often larger in diameter than conventional continuous flight auger (CFA) piles and are used to support greater loads, overcome underground obstructions, penetrate ground too hard to bore using a continuous flight auger or create piles with a cut-off level beneath the platform level.
In locations where the ground remains unstable beyond a depth practical to use temporary casing, support fluids such as bentonite or vinyl polymers can be added to support the bore during excavation.
When the concrete is poured to form the pile, the less dense support fluid is displaced and pumped into a containment unit where it is filtered and cleaned so that it may be reused.
In majority of cases in the UK, support fluids are not necessary.
When prefabricated cages are required to be greater that 12m in length and need splicing together, Van Elle utilises the RCL Super-Latch splicing system.
This enables site teams to work safely and efficiently avoiding the need to place their hands inside the cage to align the bands and tighten up bolts.
Rotary bored piles are constructed using powerful hydraulic piling rigs and a variety of interchangeable digging tools. A temporary cased is firstly installed through unstable upper strata, the soil is then removed using a variety of digging accessories such as augers, cleaning buckets and core barrels depending on the ground conditions.
On reaching the required design depth, the base of the pile is cleaned using a cleaning bucket, the reinforcement is added, and the concrete tremmied from the pile base to a predetermined level above cut-off level. The temporary casing is then removed using the piling rig and reused on the following pile position.
The temporary casing provides support during the boring and concrete process through unstable ground and safe working condition above piling platform level. Single length thin-walled casing are used where the depth of unstable ground is known and relatively shallow. Doubled walled sectional segmental casing is used where ground conditions are variable, and the temporary casing is required to depth.