Geoss Good Practice For Installation Of Jacked Foundation Piles In Singapore -

Jacking continues until "practical refusal" is reached, indicating that the pile tip has successfully entered the intended bearing stratum.

: 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.

Common defective constructions and typical malpractices are elaborated in industry training courses, with case histories used to stimulate awareness.

: When using multiple jacking machines, avoid clustering them close together to prevent cumulative ground movements. Designers must be vigilant and may require probe

Folded rock profiles can lead to drastically different pile lengths within a single pile cap. Designers must be vigilant and may require probe holes at every pile location in erratic areas like limestone.

The upcoming GEOSS revision (draft circulated July 2025) includes two major additions for jacked piles:

Execution on site dictates the long-term performance of the foundation. GeoSS emphasizes the following step-by-step operational controls. : For large pile groups

No amount of construction expertise can compensate for inadequate ground characterisation. The joint establishes mandatory requirements for ground investigation, load testing, and quality control tests for foundations of buildings of 10 storeys or more, and buildings of 5 to 9 storeys with a footprint larger than 100m². For jacked piles specifically, a thorough site investigation must address:

For the most current regulatory requirements, practitioners should refer to the latest BCA circulars and GeoSS publications available on the BCA and GeoSS websites.

Limit the maximum jacking force to 40% of the pile’s characteristic concrete cube strength ( 0.4fcu0.4 f sub c u end-sub validated termination criteria

The GEOSS framework for jacked foundation piles provides an essential blueprint for balancing aggressive urban development with structural safety and environmental responsibility. By aligning meticulous geological assessments with strict rig controls, validated termination criteria, and robust field testing, engineers in Singapore can deploy jacked piling safely and effectively. This methodology secures the foundation of Singapore's future infrastructure while safeguarding its existing urban fabric.

: 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) .