Bored Pile General Notes, Founding Criteria and Predrilling - Method Statement

Oct 24, 2026

Design and construction notes for bored pile foundations specify metric dimensions in millimeters and levels in mPD, with cap and pile-cap requirements including proposed cap top level, cap thickness, concrete grade, and pile-cap submission boundaries. The document outlines governing Hong Kong codes and load combinations for reinforced concrete design, reinforcement types and stress limits, concrete mix and strength reduction, cover, lap lengths, and fixed-head/flexible-cap assumptions. Founding criteria and predrilling requirements define acceptable rock/material quality, allowable bearing capacity and bond strength, and prescribe records and approvals, followed by a bored pile construction method statement covering setting out, drilling setup with casing, excavation methods, balanced head control, and casing extension.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages16

Reading Time40 min

AccessFree to download

General Notes

General Notes for Bored Pile

Notes on Founding Criteria and Predrilling

Method Statement of Bored Pile Construction

| GENERAL NOTES
1. ALL DIMENSIONS ARE IN MILLIMETERS (mm) UNLESS OTHERWISE STATED.
2. ALL LEVELS ARE IN METERS ABOVE PRINCIPAL DATUM(mPD) UNLESS OTHERWISE STATED.
3. ALL PROPOSED CAP TOP LEVEL SHOULD BE-3. 98mPD. THICKNESS OF CAPTO BE 2500mm. CONCRETE GRADE OF PILE CAP IS C45/20 (UNDER SEPARATE SUBMISSION)
4. ALL PILE CAP SHOULD BE UNDER SEPARATE SUBMISSION.
5. ALL FOUNDING LEVELS OF BORED PILES AS SHOWN ARE TENTATIVE ONLY.
6. HEIGHT OF BUILDING TO BE 113m.
FOR REFERENCE ONLY
7. THE DESIGN OF BORED PILING WORKS SHALL WITH HONG KONG BUILDING (CONSTRUCTION) REGULATIONS 1990, THE STRUCTURAL USE OF CONCRETE 2013, CODE OF PRACTICE ON WIND EFFECTS IN HONGKONG 2019, CODE OF PRACTICE FOR FOUNDATION 2017 AND PRACTICE NOTES FROM THE BUILDINGS DEPARTMENT.
8. HIGHEST POSSIBLE GROUNDWATER LEVEL TO BE +6. 42mPD. EXISTING GROUND LEVEL IS +6. 42mPD.
9. FLEXIBLE CAP THEORY IS ADAPTED IN PILE DESIGN.
10. ALL LATERAL LOADS ARE RESISTED BY BORED PILES & SOCKETED H-SHEET PILES.
11. WIND LOAD SHALL BE REVERSIBLE.
12. CONSIDERATION OF N.S. F. IS NOT REQUIRED.
13. THE PILE HEAD FOR BORED PILES IS ASSUMED AS FIXED.

GENERAL NOTES FOR BORED PILE
ALL STRUCTURAL DRAWINGS SHALL BE READ IN CONJUNCTION WITH ALL RELEVANT ARCHITECTURAL AND BUILDING SERVICES DRAWINGS. SETTING OUT TO BE IN ACCORDANCE WITH RELEVANT ARCHITECTURAL DRAWINGS.
1. CONCRETE USED IN BORED PILE SHALL HAVE PFA CONTENTS COMPLYING WITH PNAPAPP-33 AND NOT EXCEED 25% OF THE CEMENT CONTENT AND COMPLY WITH PNAPAPP-74. THE REACTIVE ALKALI OF CONCRETE EXPRESSED AS THE EQUIVALENT SODIUM OXIDE PER CUBIC METER OF CONCRETE SHOULD NOT EXCEED 3.0kg.
2. ALL DESIGN IS IN ACCORDANCE WITH "HONG KONG (CONSTRUCTION) REGULATION 1990"WITH LOAD COMBINATION IN ACCORDANCE WITH TABLE 2.1 OF "THE CODE OF PRACTICE FOR STRUCTURAL USE OF CONCRETE 2013" FOR REINFORCED CONCRETE DESIGN. THE LOAD COMBINATIONS INCLUDE 1. 4D+1 . 6L, 1. 4D+1 . 4W, 1. 2D+1 . 2L+1 . 2W, 1.0D-1. 4W
3. THE CONTRACTOR SHALL ESTABLISH THE BASE SETTING OUT POINTS AND LINES FOR THE ENGINEERS.
4. THE CONTRACTOR IS ADVISED TO INSPECT THE CONDITIONS ON SITE AND TO RECORD THE EXISTING LANDSCAPING FEATURES AND UTILITIES WITHIN AND CLOSE TOTHE EXCAVATION AREA. THE CONTRACTOR SHALL CARRY OUT PRECONSTRUCTION DIVERSION OF THE EXISTING UNDERGROUND UTILITIES WITHIN THE WORK AREA.
5. ALL REINFORCEMENTS ARE HIGH TENSILE DEFORMED STEEL BAR (Y) AND MILD STEEL ROUND BAR (R) COMPLYING WITH CS2 :2012 WITH MINIMUM YIELD STRESS AS FOLLOWS :
• HIGH TENSILE DEFORMED STEEL BAR = 500 N/mm2
• MILD STEEL ROUND BARS = 250 N/mOR REFERENCE ONLY
6. CONCRETE MIX FOR ALL BORED PILES TO BE GRADE C45 COMPLYING WITH HONG KONG BUILDING (CONSTRUCTION) REGULATION CONCRETING METHOD TO BE BY TREMIE. A REDUCTION FACTOR OF 0.8 SHALL BE APPLIED FOR CONCRETE STRENGTH.
7. ALL LAP LENGTHS OF REINFORCEMENT SHALL BE 46D WHERE D IS THE DIAMETER OF REINFORCEMENT.
8. CUT-OFF LEVEL AND TENTATIVE FOUNDING LEVEL FOR ALL PILES ARE SHOWN IN THE BORED PILE SCHEDULES.
9. COVER TO MAIN REINFORCEMENT FOR BORED PILES TO BE 75mm.
10. ALL DIMENSIONS ARE IN mm.
11. ALL LEVELS ARE IN mPD.
12. ESTIMATED PILE LENGTHS GIVEN IN THE PILING SCHEDULE ARE MEASURED FROM THE CUT-OFF LEVEL OF INDIVIDUAL PILES.
13. ESTIMATED PILE LENGTHS GIVEN ARE TENTATIVE. ACTUAL PILE LENGTH FOR INDIVIDUAL PILES SHALL BE VERIFIED ON SITE.
14. THE TENTATIVE FOUNDING LEVELS OF BORED-PILES ARE APPROXIMATE AS DETERMINED FROM THE BOREHOLE INFORMATION.
15. CONCRETE SHALL BE COMPILED WITH CS1 : 2010, EXCEPT CLAUSE 7.1.
16. BORED PILE IS DESIGNED AS FIXED HEAD AND PILE CAPTO BE DESIGNED AS FLEXIBLE CAP. PILE CAP SHALL BE PROVIDED AT B2/F (UNDER SEPARATE SUBMISSION)
17. NO NEGATIVE SKIN FRICTION TO BE CONSIDERED FOR PILE DESIGN DUE TO COMPLETION OF CONSOLIDATION AND REDUCTION OF OVERBURDEN PRESSURE FROM THE BASEMENT CONSTRUCTION.
18. CORRESPONDING GBP SUBMISSION AND SUBSEQUENT AMENDMENT SHALL BE SUBMITTED TOTALLY WITH THE AS-BUILT SETT

FAQs

What units and reference levels are used in the document?

All dimensions are in millimeters (mm) unless stated otherwise, and all levels are in meters above principal datum (mPD) unless stated otherwise.

Which standards and load combinations govern the bored pile design?

The design follows Hong Kong (Construction) Regulation 1990, with reinforced concrete design load combinations aligned to Table 2.1 of the Code of Practice for Structural Use of Concrete 2013, including combinations such as 4D+1.6L and 1.2D+1.2L+1.2W.

What are the founding criteria and pre-drilling requirements?

Founding stratum must be slightly to moderately decomposed rock/material with specified recovery and strength thresholds, with allowable bearing capacity set out. Pre-drilling is required for each pile to verify founding depth or rock socket depth, and pre-drilling records must be submitted for engineer approval before bored pile commencement.

Oct 24, 2026

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