Geoss Good Practice For Installation Of Jacked Foundation Piles In Singapore |top| Jun 2026

4.3 Permits and Coordination

GEOSS Good Practice for Installation of Jacked Foundation Piles in Singapore

| Problem | Cause | Good Practice Solution | |---------|-------|------------------------| | | Dense sand layer / Old Alluvium | Pre-bore 50–70% of pile depth; use shoe; reduce spacing of reaction piles | | Pile cracks during jacking | Tensile bending during eccentric load | Reduce rate; install centralizing guide; reject pile if crack >0.2 mm | | Adjacent ground heave | Full displacement in clay | Re-jack perimeter piles; install relief holes (100 mm dia., 2 m deep) | | Jacking force drops suddenly | Void / old trench backfill | Stop, inject grout, re-jack next day with lower rate | | Neighbour complaint (vibration) | Even jacking has micro-vibration | Use rubber pad at pile head; monitor with PPV <5 mm/s |

Jacked-in pile foundation systems have become a preferred choice for urban development in Singapore due to their low vibration, minimal noise, and high load-bearing capacity. The Geotechnical Society of Singapore (GEOSS) emphasizes stringent "good practice" guidelines to ensure structural integrity and compliance with Eurocode 7, especially given Singapore's complex geological conditions, including the weathered sedimentary rocks of the Jurong Formation and variable marine clays.

: Typically, piles are jacked with a force adjusted in steps to a value of 2 to 2.5 times the Working Load (WL) until practical refusal is reached. The Set Procedure : Pjcap P sub j is released to zero and immediately re-applied. The Set Procedure : Pjcap P sub j

Jacked piling has become a staple of Singapore’s urban construction landscape. Favoured for being vibration-free

Under performance‑based pile design (joint BCA/IES/ACES/GeoSS circular 2022), BCA allows the flexibility for QP(D) to submit more than one set of pile design and pile design parameters in a single submission for approval for projects adopting bored pile foundation. After obtaining written approval from the CBC of the adopted design and pile design parameters, installation of working piles can commence on site. Under the performance‑based pile design, pile optimisation can be carried out on site without the need to wait for the approval to the amendment plan.

Contractors must document the initial state of neighboring structures within the zone of influence. After obtaining written approval from the CBC of

Vertical alignment must be checked continuously using two orthogonal plumbing instruments (theodolites or spirit levels).

The "termination criteria" is perhaps the most critical phase. Good practice involves holding the jacking force at a multiple of the working load (usually 2 to 2.5 times) for a specific duration. This ensures that the pile has reached a stable stratum and minimizes future settlement. Data Management and GEOSS Alignment

The pile should be lifted into the rig's gripping mechanism and checked for verticality. Adjustments are made in the X and Y directions to achieve perfect alignment before jacking commences.

References (selective—standards and guidance to consult) Jacking Force Requirements

| Item | Action | |------|--------| | Ground truth | Review CPT/boreholes for refusal risk | | Design | Set jacking force ≥1.5× working load | | Equipment | Calibrated jacks, inclinometer, continuous logger | | Sequence | Centre-out, stage loading for sensitive clay | | Monitoring | Heave markers, tilt meters on adjacent buildings | | Testing | Static load test on 1% of piles | | Contingency | Pre-boring plan if refusal encountered |

Post-installation testing validates that the installed piles meet structural and geotechnical performance criteria. High-Strain Dynamic Testing (PDA)

Determining when a jacked pile has reached its ultimate bearing capacity requires a balance of pressure metrics and geological confirmation. Jacking Force Requirements