Geoss Good Practice For Installation Of Jacked Foundation Piles In Singapore Link Direct

┌─────────────────────────────────────────────────────────┐ │ STEP 1: INITIAL SEGMENT JACKING │ │ The pile segment is aligned and pressed using dynamic │ │ hydraulic controls monitored by calibrated gauges. │ └────────────────────────────┬────────────────────────────┘ ▼ ┌─────────────────────────────────────────────────────────┐ │ STEP 2: STEPS UP TO TERMINATION │ │ Jacking force (Pj) increases incrementally to a target │ │ termination value between 2.0 to 2.5 times the WL. │ └────────────────────────────┬────────────────────────────┘ ▼ ┌─────────────────────────────────────────────────────────┐ │ STEP 3: PRACTICAL REFUSAL │ │ The pile is driven until it achieves minimal penetration│ │ under peak jacking pressure over a set time interval. │ └────────────────────────────┬────────────────────────────┘ ▼ ┌─────────────────────────────────────────────────────────┐ │ STEP 4: PRESSURE RELEASE & RE-APPLICATION │ │ Pj is released completely to zero, then immediately │ │ re-applied without pause to verify settlement stability.│ └────────────────────────────┘ The Termination Framework

: The full jacking force is immediately re-applied without pause to confirm that the displacement remains within stable parameters and no unexpected rebound or soil relaxation undermines the toe. Geological Engineering Challenges in Singapore

: A pile is officially terminated if the net downward movement does not exceed 10 mm under a minimum holding time of 30 seconds . If the settlement is greater, the cycle must be repeated until the pile satisfies the design engineer's strict limits. 3. Ground Challenges and Mitigation Strategies

: Installations must align with BCA (Building and Construction Authority) requirements, including the submission of detailed piling plans and written confirmation before proceeding to pile caps.

: Historically limited to low-capacity, small-diameter segments, the industry now relies heavily on larger structural units, such as 600 mm diameter high-strength precast concrete spun piles . Installation Control and Refusal Criteria The ultimate geotechnical capacity of a jacked pile ( Pucap P sub u ) relates tightly to the maximum jacking force applied ( Pjcap P sub j ). GeoSS technical studies indicate that Pucap P sub u typically ranges between 0.8 Pjcap P sub j Pjcap P sub j

✅ Jacking frame calibrated (valid < 3 months) ✅ Heave markers installed on adjacent structures (max spacing 15 m) ✅ Real-time force & displacement logger active ✅ Operator has valid BCA piling supervisor card ✅ Contingency grout pump on site (within 10 m of jacking rig) ✅ Rainfall in last 24 hrs < 20 mm (to avoid soft top clay)

They packed away tools and left the site as they had found it: orderly, recorded, accountable. In the preservation of that order, in the quiet respect for what the earth revealed under pressure, the team had kept faith with the city’s future — one jacked pile at a time.

: In thick layers of soft ground, displacement piles can cause significant ground movement. Designers must evaluate the need for pre-boring or relief holes to mitigate heave and lateral soil displacement.

Good Practices for the Installation of Jacked Foundation Piles in Singapore: A GeoSS Perspective

For the official BCA guidelines on GEOSS and jacked piling in Singapore, refer to: and LTA – “Geotechnical & Structural Instrumentation for MRT Protection” (GeoSS Tech Note 3/2019)