When properly designed and constructed on competent ground, raft or piled-raft foundations can offer cost-effective solutions for high-rise buildings and infrastructure. However, proper characterization of subsurface geological conditions is critical. The guideline establishes (high, medium, low) for buildings, with corresponding design and construction requirements specified in Annex B.

Proposals for reuse of other pile types require case-by-case review.

Highly favored in soft clays and silts for providing a continuous profile of tip resistance and pore water pressure.

Detection of sulfate-rich soils and groundwater requires specialized cement types to ensure pile longevity. 4. Transition to Eurocodes (SS EN 1997)

Local guidelines typically allow for:

To prevent soil contamination and concrete segregation under water or drilling slurry, concrete must be discharged through a continuous tremie pipe kept submerged within the fresh concrete pool. Driving Criteria

Use of bentonite or polymer slurry to stabilize the borehole. 2.2 Driven Piles (Precast and Steel) For driven piles, GeoSS guidelines emphasize:

The circular, effective from 1 April 2017, superseded the earlier Advisory Note 1/03 and remains the authoritative reference for deep foundation testing submissions to the Commissioner of Building Control. Notably, the circular includes a critical caveat: Qualified Persons must exercise independent judgment and evaluation on whether more stringent requirements should be adopted, especially where ground conditions could be adverse or highly variable.

Ensures direct, high-capacity load transfer to competent rock. 3. Engineering Design Methodologies Under GEOSS

This guide is for educational purposes and summarizes general local practices. Always consult the specific local Code of Practice (e.g., Hong Kong Buildings Department Code of Practice for Foundations) and relevant GEO Publications for legally binding requirements.

Technical formulas for calculating in local soils. GeoSS Guidelines

Dynamic testing or Pile Integrity Testing (PIT) to check for shaft defects. 3. Adaptation to Local Geology (Special Cases)

: Jacking continues until practical refusal is achieved, then the load is released to zero and re-applied without pause to confirm stability.

The provides a more objective assessment system for identifying rock during bored piling works. Key features include:

While "GEOSS" is often used to refer to the digital submission system and standards in Hong Kong, the technical guidelines for pile foundations are derived from key publications such as and GEO Publication No. 2/96 (Pile Design and Construction) .

Provides high-resolution digital elevation models (DEMs) to evaluate slope stability and landslide risks around pile groups.