Geoss Good Practice For Installation Of Jacked Foundation Piles In Singapore !link! Jun 2026

The "set" of a jacked pile is verified through a rigorous re-jacking process to confirm stability Course Hero The pile is jacked to a force ( cap P sub j ) usually between 2.0 to 2.5 times the Working Load (WL) until practical refusal Course Hero

Calibrate jacks every 6 months or after 10,000 cycles. Maintain digital record of jack pressure vs. force.

Because jacking is silent, complacency is the risk. GEOSS adds a chapter on – even jacked piles can produce ground-borne vibrations if stones are crushed at the toe. Limits:

: For larger pile groups, it is recommended to jack from the inside out or in a consistent direction (e.g., left to right) to manage soil displacement effects. The "set" of a jacked pile is verified

The hydraulic jacking machine must be sized appropriately for the design load. A key good practice is the regular calibration of hydraulic gauges. Since the pile capacity is often inferred from the jacking pressure, inaccurate gauges can lead to catastrophic foundation failure. Furthermore, the machine must be perfectly leveled. Even a slight tilt during setup can lead to eccentric loading, causing the pile to deviate from its vertical alignment or crack under pressure. Execution and Monitoring

The circular applies to projects with the and is enforceable by the BCA.

Complies with strict National Environment Agency (NEA) noise limits in residential areas. Because jacking is silent, complacency is the risk

Not all piles can be jacked. GEOSS specifies:

| Test | Requirement | |------|-------------| | | 1% of piles, up to 1.5× working load (max 2.0× for proof test) | | PDA / high-strain dynamic test | 5% of piles (correlated with jacking records) | | Sonic logging (for large diameter >400 mm) | If specified by design | | Heave monitoring | 2–3 benchmarks near pile group |

: In soft consolidating soil, designers must account for "downdrag" forces that reverse the direction of shaft resistance over time. Site Investigation (SI) The hydraulic jacking machine must be sized appropriately

When connecting prefabricated pile segments, welding must be executed by certified welders.

Introduction Jacked foundation piles (hydraulically driven displacement piles and pre-bored jacked piles) are widely used in Singapore for deep foundations where vibration minimization, tight site access, and load performance are critical. Singapore’s reclaimed land, alluvial deposits, marine clay layers, and dense urban fabric require tailored procedures to mitigate settlement, ground disturbance, and risks to nearby structures and utilities. This paper outlines GEOSS Good Practice covering site investigation, pile selection and design, installation methodology, instrumentation and monitoring, quality control, environmental and safety management, and post-installation validation.

Hydraulic gauges and load cells must hold valid calibration certificates from accredited laboratories.

In Singapore’s marine clay, a jacked pile gains capacity over time (thixotropic setup). GEOSS provides a time-dependent factor:

Before any piling work begins, a pre-construction survey is mandatory to document the condition of adjacent buildings. This establishes a baseline for any claims of damage and is a core component of a good practice impact assessment.