Singapore is not Hong Kong, and it is certainly not London. The GEOSS guidelines acknowledge five unique local challenges:
The GEOSS good practice bridges the gap between international standards (BS EN 14199, Eurocode 7) and Singapore’s legislative reality (Building Control Act, LTA’s Civil Design Criteria).
Jacked piles are displacement piles—they squeeze soil sideways, which can uplift previously installed piles (especially in marine clay).
GEOSS-approved sequence good practices:
| Site Condition | Recommended Sequence |
|----------------|----------------------|
| Single isolated pile | No special sequence. |
| Group of piles (≤9) | Center-outwards or spiral. |
| Long pile rows (e.g., for retaining walls) | Staggered, with pre-drilled pilot holes (50–70% pile diameter) to reduce displacement. |
| Adjacent to MRT / existing building | Install “sacrificial” or “guard” piles first, then inner piles. Use extremely low jacking rates (<5 mm/s). |
Critical: Re-jack all piles in a group after 24–48 hours of set-up to confirm no loss of capacity due to heave.
Heave check: After each new segment is welded (for steel) or jointed (for precast), re-check the level of adjacent piles (within 5 diameters). If heave >5mm, pause and relieve pore pressure.
Manual recording is no longer sufficient for Category III works. Good practice mandates:
GEOSS submission: PIRs and summary sheets must be endorsed by the RE within 24 hours and available for audit.
For any jacked pile in Singapore, the following records must be kept for inspection by BCA (Building & Construction Authority) and LTA:
A sample entry (GEOSS Format):
| Depth (m) | Jack Force (kN) | Penetration Rate (mm/min) | Verticality (%) | Notes |
|-----------|----------------|---------------------------|----------------|---------------------------|
| 0.0-5.0 | 200 → 800 | 1500 | 0.05 | Through fill, no rebound |
| 5.0-9.5 | 800 → 2100 | 1200 | 0.10 | Soft clay; steady |
| 9.5-10.2 | 2100 → 3800 | 300 | 0.20 | Sand layer; moderate |
| 10.2 | 3800 (steady) | 50 over 150mm | 0.25 | Refusal achieved |
Maintain a daily piling record including:
