The Geotechnical Society of Singapore (GeoSS) provides guidelines for jacked foundation pile installation, emphasizing stringent controls on verticality, equipment calibration, and sequence to manage ground movement. Installation requires a re-jack process to reach specific settlement "set" criteria, typically 10mm or less, to ensure structural integrity. For the full guide, visit GeoSS.
The Geotechnical Society of Singapore (GeoSS) guidelines for jacked foundation piles recommend using jacking machines up to approximately 75% of their maximum capacity to ensure safety and performance. Piles are typically jacked to 2 to 2.5 times the Working Load, with a "set" defined as a downward movement not exceeding 10 mm over a 30-second hold time upon reaching refusal. Read the full Guideline on Jacked Piles (GeoSS) at Course Hero Course Hero
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Introduction
Singapore, being a densely populated urban city-state, requires a robust and efficient foundation system to support its numerous high-rise buildings, infrastructure projects, and industrial developments. Jacked foundation piles have become a popular choice for deep foundation systems in Singapore due to their cost-effectiveness, minimal environmental impact, and ability to support high loads. However, the installation of jacked foundation piles requires careful planning, execution, and monitoring to ensure their stability, safety, and performance. This essay will discuss the good practices for the installation of jacked foundation piles in Singapore.
Pre-Installation Planning
Before commencing the installation of jacked foundation piles, it is essential to conduct thorough site investigations to determine the subsurface conditions, soil properties, and potential hazards. This includes drilling boreholes, conducting standard penetration tests (SPT), and collecting soil samples to determine the soil's geotechnical properties. The site investigation report should provide essential information on the soil's stratigraphy, groundwater levels, and potential liquefaction risks.
Design and Pile Specification
The design of jacked foundation piles should be based on the site investigation report and relevant design codes, such as the Singapore National Annex to Eurocode 7. The pile specifications should include details on the pile type, diameter, length, and material properties. The design should also consider factors such as pile capacity, settlement, and soil-structure interaction.
Installation Techniques
The installation of jacked foundation piles involves driving or jacking the piles into the ground using a hydraulic jack or a pile driving rig. The piles are typically installed in a sequence, starting from the center of the pile group and working outward. The installation process should be monitored closely to ensure that the piles are installed at the correct angle, depth, and alignment.
Good Practice Guidelines
The following good practice guidelines should be followed during the installation of jacked foundation piles in Singapore:
Case Study
A recent project in Singapore involved the installation of jacked foundation piles for a high-rise residential building. The site investigation report revealed a complex soil stratigraphy with layers of soft marine clay, stiff clay, and weathered rock. The design required the installation of 600 mm diameter jacked foundation piles to a depth of 60 m. The installation process was closely monitored, and pile integrity tests were performed on a sample of piles to verify their integrity. The results showed that the piles were installed to the required depth and capacity, with minimal settlement and lateral displacement.
Conclusion
The installation of jacked foundation piles in Singapore requires careful planning, execution, and monitoring to ensure their stability, safety, and performance. By following good practice guidelines, such as accurate pile positioning, soil disturbance minimization, pile driving control, pile integrity testing, and quality control, the risk of pile failure can be minimized, and the performance of the foundation system can be optimized. The case study demonstrates the importance of good practice guidelines in ensuring the successful installation of jacked foundation piles in Singapore. Building and Construction Authority (BCA) of Singapore :
References
You can find more information and detailed guidelines on the installation of jacked foundation piles in Singapore from the following sources:
The Geotechnical Society of Singapore (GeoSS) developed guidelines to standardize the installation of jacked foundation piles, focusing on safety, environmental benefits, and technical compliance with Eurocode 7 (EC7). Core Installation & Termination Criteria
A critical aspect of GeoSS practice is the "set" criteria used to determine when a pile has reached sufficient depth and capacity: Jacking Force ( Pjcap P sub j
): Piles are typically jacked into the ground with a force adjusted in steps, reaching a value of 2 to 2.5 times the working load (WL).
Release and Re-jack Process: Once refusal is reached, the force is released to zero and immediately reapplied without pause. The movement between these two stages is measured.
The "Set" Definition: A pile is considered "set" if the downward movement does not exceed 10 mm with a minimum holding time of 30 seconds. GeoSS recommends achieving two consistent sets.
Shorter Piles: If termination criteria are met but the pile is significantly shorter than the design depth, a designer must assess if the shallower depth is acceptable. Operational Good Practices
GeoSS emphasizes several operational standards to ensure structural integrity and efficiency: Some specific search terms you can try:
Alignment: The alignment of a pile should not be adjusted by force once installation has begun, as this can cause structural damage.
Installation Sequence: For large pile groups, it is recommended to install from the inside out or in a consistent direction (e.g., left to right) to manage soil displacement and "squeezing" effects.
Machinery Limits: It is recommended that jacking machines be used at roughly 75% of their maximum capacity (e.g., using an 800-tonne machine for a 600-tonne requirement) to ensure stability and reduce the risk of mechanical failure. Advantages and Site Considerations
Jacked piles are preferred in Singapore's urban environment due to specific performance characteristics:
Environmentally Friendly: The method is virtually vibration-free and has very low noise levels compared to driven piles, making it ideal for congested areas like residential developments.
Control: It provides high verticality control and avoids "over-penetration" risks.
Working Space: While clean, the machinery is heavy and requires a strong platform and a larger working area than some other methods.
For full technical details, you can reference the Guideline on Jacked Piles Draft (GeoSS) or related Geotechnical Capacity documents.
If you are working on a specific project, let me know the soil type (e.g., Bukit Timah Granite or Jurong Formation) or the building height so I can provide more tailored design parameters. rate of penetration