Low-vibration continuous flight auger piling — purpose-built FD45 restricted-access rig.
Continuous Flight Auger (CFA) piling is a bored pile method that produces a cast in-place concrete pile with minimal noise and vibration. Our FD45 rig installs piles from 450 mm to 600 mm in diameter to depths up to 20 m in a single continuous drilling pass. Unlike driven piling, CFA bores the pile hole rather than displacing ground by impact, making it the method of choice for projects adjacent to sensitive structures, in urban environments where vibration limits apply, or on brownfield sites where ground disturbance to neighbouring buildings is a constraint.
The FD45 is purpose-built for restricted access — it can work in confined urban sites, under low headroom, and in locations where standard piling rigs cannot operate. This makes it particularly well suited to New Zealand's urban infill and brownfield development projects. CFA piling performs well in soft clays, loose sands, and variable fills (ground types common in urban New Zealand) and can be paired with contiguous or secant pile arrangements to form retaining walls for excavations and basements. All CFA piling works are designed and supervised by our in-house geotechnical engineers, with full QA records and as-built pile schedules on completion.
APPLICATIONS
GSI NZ CAPABILITY
THE GSI DIFFERENCE
Step 1
Ground conditions, services, and obstructions are confirmed before mobilisation. The survey defines pile design parameters and identifies any risks. Our engineers produce the pile layout, concrete specification, and reinforcement design based on this data.
Step 2
The hollow-stem CFA auger drills to design depth in a single continuous pass. Structural concrete is pumped under pressure through the hollow stem as the auger is withdrawn, and the reinforcement cage is installed into the fresh concrete immediately after.
Step 3
Piles are tested to the agreed programme — static load, PDA dynamic testing, or low-strain integrity testing. All test data and QA records are compiled into a completion report with as-built pile schedules for client records.
CASE STUDY
GSI NZ was engaged by Fulton Hogan to deliver CFA piling and a GCS wall on a constrained coastal site at Marine Parade. The site's restricted access and proximity to existing structures made the FD45 rig the only viable piling solution.
Works were completed in January 2023. The project demonstrated the FD45's capability in the challenging combination of restricted access, low headroom, and coastal ground conditions, a combination that eliminates most standard piling options.
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CFA piling and GCS wall on a constrained coastal site, using the FD45 restricted-access rig.
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Ground improvement and foundation works for major Christchurch aquatic facility.
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126 soil-cement columns to stabilise an active landslide mass, Central Hawke's Bay.
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Our CFA piling crews operate across New Zealand with our own rigs and in-house engineering. Fast programme, minimal vibration, delivered under one contract.
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