One of the most critical aspects covered in the guide is knowing when to stop.
| Parameter | Frequency | Acceptance | |-----------|-----------|------------| | Jacking force | Continuous recording | ≥ design capacity at toe level | | Pile penetration rate | Every 0.5 m | Sudden drop indicates fracture or void | | Verticality | Every 3 m | ≤0.5% for LTA; ≤1% for BCA | | Toe level survey | Every pile | ±25 mm |
Keywords used throughout: GEOSS good practice for installation of jacked foundation piles in Singapore, jacked piling, ground heave, termination criteria, Kallang Formation, CPTu, set-up phenomenon, integrity testing.
The Geotechnical Society of Singapore (GeoSS) has established guidelines for the installation of jacked foundation piles, focusing on ensuring structural integrity and minimizing ground disturbance in Singapore's diverse geological conditions. Key Good Practices for Installation
The following practices are recommended by the GeoSS Guideline on Jacked Piles to ensure quality and safety during construction: Verticality and Alignment:
The pile's verticality must be checked throughout the process.
Crucial Rule: Piles should not have their alignment adjusted by force once installation has begun.
Jacking Sequence: For large pile groups, jacking should proceed from the inside out or in a specific direction (e.g., left to right) to manage ground displacement effectively. "Set" and Termination Criteria: Piles are typically jacked with a force ( Pjcap P sub j ) of 2 to 2.5 times the Working Load (WL).
A pile is considered "set" if downward movement does not exceed 10 mm over a holding time of at least 30 seconds.
It is recommended to achieve two consistent sets by releasing and reapplying the load without pause. Environmental & Site Management:
Because jacking machines are heavy, the working platform must be high-quality, well-compacted, and have adequate site drainage.
When multiple machines are used, they should not be clustered too closely to avoid excessive ground movement. Common Installation Issues & Mitigations
Practitioners must be vigilant about specific risks associated with displacement piles in Singapore's soft clay or sedimentary formations: One of the most critical aspects covered in
Pile Heave: The installation of adjacent piles can cause an already installed pile to lift (heave), potentially reducing its capacity or separating the pile base from its bearing layer. Monitoring for heave is essential.
Short Piles: These can occur when hitting boulders or intermediate hard soil layers. If a pile is more than 20% shorter than the design depth, an amendment plan is required, or its capacity must be verified through additional load tests.
Downdrag (Negative Skin Friction): If a pile penetrates a consolidating soft soil layer, the force direction may reverse over time. This long-term "negative skin friction" must be accounted for in the magnitude of the jacking load during installation. Quality Control & Testing
Integrity Testing: Various tests are used to assess underground defects, including Sonic Logging, PDA/PIT (Pile Driving Analyzer/Pile Integrity Test), and Full Coring.
Load Testing: Standard practice often involves Ultimate Load Tests (ULT) loaded to 3x WL and Working Load Tests (WLT) loaded to 2x WL to verify stiff settlement behavior.
scribd.com/document/92651540/GEOSS-Guidelines-on-Good-Practices-for-Pile-Load-Test">Kentledge Method in Singapore?
The Geotechnical Society of Singapore (GeoSS) provides specific guidelines for the installation of jacked foundation piles to manage ground displacement and protect adjacent structures, which is critical in Singapore's dense urban environment. Key Good Practice Guidelines (GeoSS)
According to the GeoSS draft guidelines, several proactive measures should be implemented to mitigate the adverse impacts of ground movement:
Relief Wells: Install bored holes (typically 400mm to 600mm in diameter) at strategic locations, such as boundaries near neighboring services or structures, to provide a path for displaced soil.
Pre-boring: Use pre-boring at the pile point to reduce the force required for installation and minimize soil displacement.
Machine Management: When using multiple jacking machines, avoid clustering them close together to prevent cumulative ground movements.
Platform Quality: Ensure the working platform is of high quality, specifically regarding compaction and site drainage, as jacked machines can be extremely heavy. 6.2 Near Buried Utilities (PUB
Monitoring Programs: Implement rigorous monitoring of ground and building movement throughout the piling process.
Trial Installations: Conduct a trial on the first pile installation to observe ground performance before proceeding with full-scale work.
Recording Data: Maintain records of the jacking force at every 0.5m to 1.0m of penetration to verify performance against design assumptions. Relevant Reports and Regulatory Documents
For more detailed technical requirements, you can refer to these official resources:
Good Practice for Installation of Jacked Foundation Piles (BCA): A key guideline published on October 8, 2015, which aligns with industry best practices.
GeoSS Guideline on Jacked Piles (Draft): A comprehensive technical draft covering ground movement control and protective measures.
Performance-Based Pile Design Guidelines: A joint circular from BCA, IES, ACES, and GeoSS (2022) regarding ultimate load testing and design verification.
Requirements and Guidelines on Driven or Jacked Piles: The Building and Construction Authority (BCA) updated these requirements as of September 1, 2022. Guidelines for ST Plan Applications
Headline: Setting the Standard: Navigating GEOSS Good Practice for Jacked Foundation Piles in Singapore
In the dense urban landscape of Singapore, where noise sensitivity and strict vibration limits are paramount, jacked foundation piles (also known as jacked-in piles or static pile jacking) have become the preferred solution for many infrastructure and building projects.
However, successful implementation requires rigorous adherence to quality standards. This is where the Geotechnical Engineering Office (GEO) of Singapore provides essential direction through its Good Practice Guide.
Whether you are a geotechnical engineer, a resident engineer, or a contractor, understanding these guidelines is critical for ensuring structural integrity and site safety. a resident engineer
Here is a breakdown of the key "Good Practice" requirements for the installation of jacked piles in Singapore:
Unlike driven piles, jacked piles require a controlled, steady penetration rate.
6.1 Adjacent to MRT (LTA Requirement)
6.2 Near Buried Utilities (PUB, SP Group)
6.3 Noise & Vibration (NEA)
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 |
For the full GEOSS document (2021 edition) and the latest addendum on jacked piles, visit the Singapore Society for Geotechnical Engineering (SSGE) portal.
End of Article
Title: GEOSS Good Practice for Installation of Jacked Foundation Piles in Singapore
Document ID: GEOSS-GP-JP-2026 Revision: 1.0 Date: April 2026
| Standard | Title | |----------|-------| | SS EN 1997-1 | Geotechnical design – General rules | | BCA “Piling” CP 4 (historical reference) | Still referenced for workmanship | | SS EN 12699 | Execution of special geotechnical works – Displacement piles | | LTA Civil Design Criteria | For transport infrastructure projects |