) is typically related to the ultimate geotechnical capacity ( cap P sub u ), often set at 2.0 to 2.5 times the working load (WL) Set Criterion:
Excessive jacking force crushes the pile head or overstresses the shaft.
Pile testing must be conducted under the direct supervision of a designated person .
Site Investigation and Ground Characterization 2.1 Objectives
GEOSS Good Practice for Installation of Jacked Foundation Piles in Singapore ) is typically related to the ultimate geotechnical
Pile verticality must be strictly monitored in two orthogonal directions using total stations or spirit levels.
Adjacent jacking actions can cause previously installed piles to heave, potentially separating the pile base and losing end bearing. Monitoring for heave is critical, and measures like pre-boring or relief wells should be used if necessary.
"Set" for jacked piles is defined as the jacking pressure required to advance the pile by a final 10 mm. GEOSS specifies:
Proper welding of pile joints is critical to maintaining structural continuity. Joints must be clean and strong enough to withstand the jacking forces. GEOSS specifies: Proper welding of pile joints is
Once design parameters are verified via ULT, the Qualified Person (QP) must obtain written concurrence and submit interpretation reports to the BCA before commencing working pile installation.
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.
: According to Singapore Accreditation Council (SAC) CT32 criteria , specialist piling builders under G2 and G3 categories must maintain at least three operational jacked rigs. These rigs require minimum counterweights of 200 tonnes and 400 tonnes respectively to safely exert downward forces.
Overview of GEOSS Guide 7 and Regulatory Requirements for Jacked Piles Context: Singapore Building Control (Accredited Checkers) Regulations Primary Reference: GEOSS Guide 7 (Geotechnical Engineering Society of Singapore) the working platform must be high-quality
Pre-drilling at the pile point to a specified depth (e.g., above sensitive utility lines) to minimize displacement. The hole diameter should be slightly smaller than the pile to maintain shaft resistance. Machine Management:
Given the massive weight of jacking machines, the working platform must be high-quality, with strict requirements for compaction and site drainage. Verticality:
To regulate the execution of these systems, the , in alignment with the Building and Construction Authority (BCA) and Eurocode 7 (EC7) standards, establishes stringent guidelines for the design, execution, and monitoring of jacked foundation piles. This comprehensive guide outlines the best engineering practices, installation parameters, and site-control measures required for executing jacked piling successfully under Singapore’s complex geological conditions. 1. Regulatory Context and Singapore Standards
Never adjust a pile’s alignment by force during the jacking process; this can compromise the structural integrity of the pile. Strategic Jacking Sequence: For large pile groups, always work from inside out
Ground water tables must be mapped to assess the risk of excess pore water pressure generation during high-displacement jacking. Neighboring Structure Survey
Common types of jacked piles in Singapore include: