Bored Piles for high-load deep foundations
Bored piles are cast-in-place reinforced concrete piles, formed by drilling a shaft with a rotary rig, installing a reinforcement cage and placing concrete. They carry high loads to competent strata and can be built to large diameters and depths.
Suitable ground conditions and applications
Can be considered where…
- High structural loads: buildings, bridges and industrial structures.
- Competent strata at depth, including rock sockets.
- Sites where vibration and noise from driven piles are not acceptable.
Limitations
- Shafts in loose or water-bearing soils need temporary casing or support fluid.
- Spoil must be removed and managed.
- Quality depends on a clean base and a continuous concrete supply.
Suitability is confirmed from the site investigation and the performance requirement.
How it works
The shaft is drilled with augers, buckets or core barrels. Where the ground is unstable, a temporary steel casing or a support fluid such as bentonite or polymer keeps the shaft open.
The base is cleaned, the reinforcement cage is lowered in and concrete is placed, through a tremie pipe from the bottom up where the shaft holds water or support fluid. Any temporary casing is then withdrawn.
Design inputs
- Site investigation: soil and rock profile, groundwater.
- Loads: compression, tension and lateral.
- Pile diameter, length and socket requirements.
- Concrete and reinforcement specification.
- Design standard and verification requirements.
Trial and calibration
- Preliminary test piles loaded to confirm the design, where specified.
- Construction method confirmed on the first working piles.
Execution controls
- Position, verticality and depth.
- Strata confirmation against the design.
- Support fluid properties, where used.
- Base cleaning before concreting.
- Concrete volume compared with theoretical volume; tremie embedment; concrete samples.
- Pile record for every pile.
Verification and acceptance
Design intent, production control and acceptance verification are kept separate, so it is always clear what was required, what was done and what was proven.
What is required
Design loads, capacity and settlement criteria agreed with the consultant.
What was done
Pile records: depth, strata, fluid, concrete volume.
What was proven
Static or dynamic load tests, integrity tests and concrete strength tests.
Deliverables
- Method statement and risk assessment
- Pile layout drawings
- Pile records
- Concrete test results
- Load and integrity test reports
- As-built records
Common questions
When are bored piles used?
For high structural loads, where competent strata are deep or a rock socket is needed, and where vibration must be kept low.
Why is casing or support fluid used?
A temporary steel casing, or a support fluid such as bentonite or polymer, keeps the shaft stable in loose or water-bearing ground. The choice depends on the ground conditions.
How are bored piles tested?
Static or dynamic load tests confirm capacity. Integrity tests (low-strain or cross-hole sonic logging) check that the pile is sound.
Discuss whether Bored Piles fits your ground conditions.
Share the site location, the investigation report and the performance requirement.