FOUNDATION DESIGN AND CONSTRUCTION

376 Pages·2006·3.68 MB·English

GEO PUBLICATION No. 1/2006

FOUNDATION DESIGN AND
CONSTRUCTION
GEOTECHNICAL ENGINEERING OFFICE
Civil Engineering and Development Department
The Government of the Hong Kong
Special Administrative Region
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© The Government of the Hong Kong Special Administrative Region

First published, 2006

Prepared by :

Geotechnical Engineering Office,

Civil Engineering and Development Department,

Civil Engineering and Development Building,

101 Princess Margaret Road,

Homantin, Kowloon,

Hong Kong.

Captions of Figures on the Front Cover

Top Left : Construction of Large-diameter Bored Piles

Top Right : Pile Loading Test Using Osterberg Load Cell

Bottom Left : Foundations in Marble

Bottom Right : Construction of Large-diameter Bored Piles on Slope
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FOREWORD

This publication is a reference document that presents a review of the principles and
practice related to design and construction of foundation, with specific reference to ground
conditions in Hong Kong. The information given in the publication should facilitate the use
of modern methods and knowledge in foundation engineering.

The Geotechnical Engineering Office published in 1996 a reference document (GEO
Publication No. 1/96) on pile design and construction with a Hong Kong perspective. In
recent years, there has been a growing emphasis on the use of rational design methods in
foundation engineering. Many high-quality instrumented pile loading tests were conducted,
which had resulted in better understanding of pile behaviour and more economic foundation
solutions. The Geotechnical Engineering Office sees the need to revise the publication to
consolidate the experience gained and improvement made in the practice of foundation
design and construction. The scope of the publication is also expanded to cover the key
design aspects for shallow foundations, in response to the request of the practitioners. Hence,
a new publication title is used.

The preparation of this publication is under the overall direction of a Working Group.
The membership of the Working Group, given on the next page, includes representatives
from relevant government departments, the Hong Kong Institution of Engineers and the
Hong Kong Construction Association. Copies of a draft version of this document were
circulated to local professional bodies, consulting engineers, contractors, academics,
government departments and renowned overseas experts in the field of foundation
engineering. Many individuals and organisations made very useful comments, many of
which have been adopted in finalising this document. Their contributions are gratefully
acknowledged.

The data available to us from instrumented pile loading tests in Hong Kong are
collated in this publication. Practitioners are encouraged to help expand this pile database by
continuing to provide us with raw data from local instrumented pile loading tests. The data
can be sent to Chief Geotechnical Engineer/Standards and Testing.

Practitioners are encouraged to provide comments to the Geotechnical Engineering
Office at any time on the contents of the publication, so that improvements can be made in
future editions.

Raymond K S Chan

Head, Geotechnical Engineering Office

January 2006
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WORKING GROUP :

Architectural Services Department
Mr. Li W.W.

Buildings Department
Mr. Cheng M.L.

Civil Engineering and Development Department
Mr. Pun W.K. (Chairman)

Mr. Ken Ho K.S.

Dr. Richard Pang P.L.

Mr. Vincent Tse S.H.

Dr. Dominic Lo O.K.

Mr. Sammy Cheung P.Y. (Secretary)

Highways Department
Mr. Li W. (before 1 December 2004)

Mr. Yeung S.K. (between 1 December 2004 and 3 May 2005)

Mr. Anthony Yuen W.K. (after 3 May 2005)

Hong Kong Construction Association (Piling Contractor Subcommittee)
Mr. David Chiu C.H.

Hong Kong Institution of Engineers (Civil Division)
Mr. Timothy Suen

Hong Kong Institution of Engineers (Geotechnical Division)
Dr. Daman Lee D.M.

Hong Kong Institution of Engineers (Structural Division)
Mr. Kwan K.K.

Housing Department
Dr. John Lai Y.K.
Mr. Pang C.F.
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CONTENTS

Page

No.

TITLE PAGE 1

FOREWORD 3

WORKING GROUP 4

CONTENTS 5

LIST OF TABLES 15

LIST OF FIGURES 17

LIST OF PLATES 21

1. INTRODUCTION 23

1.1 PU RPOSE AND SCOPE 23

1.2 GE NERAL GUIDANCE 24

2. SITE INVESTIGATION, GEOLOGICAL MODELS AND 25

SELECTION OF DESIGN PARAMETERS

2.1 GE NERAL 25

2.2 DE SK STUDIES 25

2.2.1 Site H istory 25

2.2.2 Details of Adjacent Structures and Existing Foundations 26

2.2.3 Geol ogical Studies 26

2.2.4 Grou ndwater 33

2.3 EXECUTION OF GROUND INVESTIGATION 33

2.4 EXTENT OF GROUND INVESTIGATION 33

2.4.1 General Sites 33
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2.4.2 Sites Underlain by Marble 34

2.5 SOIL AND ROCK SAMPLING 36

2.6 DETECTION OF AGGRESSIVE GROUND 36

2.7 INSITU AND LABORATORY TESTING 37

2.8 ESTABLISHING A GEOLOGICAL MODEL 38

2.9 SELECTION OF DESIGN PARAMETERS 39

3. SHALLOW FOUNDATIONS 41

3.1 GENERAL 41

3.2 DESIGN OF SHALLOW FOUNDATIONS ON SOILS 42

3.2.1 Determination of Bearing Capacity of Soils 42

3.2.1.1 General 42

3.2.1.2 Empirical methods 42

3.2.1.3 Bearing capacity theory 42

3.2.2 Foundations On or Near the Crest of a Slope 46

3.2.3 Factors of Safety 46

3.2.4 Settlement Estimation 48

3.2.4.1 General 48

3.2.4.2 Foundations on granular soils 49

3.2.4.3 Foundations on fine-grained soils 50

3.2.5 Lateral Resistance of Shallow Foundations 51

3.3 DESIGN OF SHALLOW FOUNDATIONS ON ROCK 51

3.4 PLATE LOADING TEST 52

3.5 RAFT FOUNDATIONS 53

4. TYPES OF PILE 55

4.1 CLASSIFICATION OF PILES 55

4.2 LARGE-DISPLACEMENT PILES 56

4.2.1 General 56

4.2.2 Precast Reinforced Concrete Piles 56

4.2.3 Precast Prestressed Spun Concrete Piles 57

4.2.4 Closed-ended Steel Tubular Piles 57
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4.2.5 Driven Cast-in-place Concrete Piles 58

4.3 SM ALL-DISPLACEMENT PILES 58

4.3.1 Gene ral 58

4.3.2 Steel H-piles 58

4.3.3 Open-ended Steel Tubular Piles 59

4.4 R EPLACEMENT PILES 59

4.4.1 Gene ral 59

4.4.2 Machine-dug Piles 59

4.4.2.1 Mini-piles 60

4.4.2.2 Socketed H-piles 60

4.4.2.3 Continuous flight auger piles 60

4.4.2.4 Large-diameter bored piles 61

4.4.2.5 Barrettes 61

4.4.3 Hand -dug Caissons 62

4.5 SP ECIAL PILE TYPES 65

4.5.1 Gene ral 65

4.5.2 Shaft- and Base-grouted Piles 65

4.5.3 Jack ed Piles 66

4.5.4 Com posite Piles 67

5. CHOICE OF PILE TYPE AND DESIGN RESPONSIBILITY 69

5.1 GE NERAL 69

5.2 FACTORS TO BE CONSIDERED IN CHOICE OF PILE TYPE 69

5.2.1 G round Conditions 69

5.2.2 Complex Ground Conditions 71

5.2.3 Nature of Loading 73

5.2.4 Effects of Construction on Surrounding 73

Structures and Environment

5.2.5 Site and Plant Constraints 74

5.2.6 Safet y 74

5.2.7 Programme and Cost 75

5.3 REUSE OF EXISTING PILES 75

5.3.1 Gene ral 75

5.3.2 Verifications of Conditions 76

5.3.3 Durability Assessment 76

5.3.4 Load-carrying Capacity 77

5.3.5 Other Design Aspects 77

5.4 DE SIGN RESPONSIBILITY 78
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5.4.1 Contractor's Design 78

5.4.2 Engineer's Design 78

5.4.3 Discussions 79

6. DESIGN OF SINGLE PILES AND DEFORMATION OF PILES 81

6.1 GENERAL 81

6.2 PILE DESIGN IN RELATION TO GEOLOGY 81

6.3 DESIGN PHILOSOPHIES 82

6.3.1 General 82

6.3.2 Global Factor of Safety Approach 82

6.3.3 Limit State Design Approach 82

6.3.4 Discussions on Design Approaches 84

6.3.5 Recommended Factors of Safety 85

6.3.6 Planning for Future Redevelopments 87

6.4 AXIALLY LOADED PILES IN SOIL 87

6.4.1 General 87

6.4.2 Pile Driving Formulae 88

6.4.3 Wave Equation Analysis 91

6.4.4 Use of Soil Mechanics Principles 91

6.4.4.1 General 91

6.4.4.2 Critical depth concept 91

6.4.4.3 Bored piles in granular soils 93

6.4.4.4 Driven piles in granular soils 97

6.4.4.5 Bored piles in clays 98

6.4.4.6 Driven piles in clays 99

6.4.4.7 Other factors affecting shaft resistance 100

6.4.4.8 Effect of soil plug on open-ended pipe piles 100

6.4.5 Correlation with Standard Penetration Tests 101

6.4.5.1 General 101

6.4.5.2 End-bearing resistance 101

6.4.5.3 Shaft resistance 101

6.4.6 Correlation with Other Insitu Tests 103

6.5 AXIALLY LOADED PILES IN ROCK 103

6.5.1 General 103

6.5.2 Driven Piles in Rock 104

6.5.3 Bored Piles in Rock 104

6.5.3.1 General 104

6.5.3.2 Semi-empirical methods 105

6.5.3.3 Bearing capacity theories 111

6.5.3.4 Insitu tests 111
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6.5.3.5 Presumptive bearing values 111

6.5.4 Rock Sockets 114

6.6 UPLIFT CAPACITY OF PILES 117

6.6.1 Piles in Soil 117

6.6.2 Rock Sockets 119

6.6.3 Cyclic Loading 120

6.7 LATERAL LOAD CAPACITY OF PILES 121

6.7.1 Vertical Piles in Soil 121

6.7.2 Inclined Loads 129

6.7.3 Raking Piles in Soil 129

6.7.4 Rock Sockets 129

6.7.5 Cyclic Loading 131

6.8 NEGATIVE SKIN FRICTION 131

6.8.1 General 131

6.8.2 Calculation of Negative Skin Friction 132

6.8.3 Field Observations in Hong Kong 134

6.8.4 Means of Reducing Negative Skin Friction 135

6.9 TORSION 135

6.10 PRELIMINARY PILES FOR DESIGN EVALUATION 135

6.11 PILE DESIGN IN KARST MARBLE 137

6.12 STRUCTURAL DESIGN OF PILES 141

6.12.1 General 141

6.12.2 Lifting Stresses 141

6.12.3 Driving and Working Stresses 141

6.12.4 Bending and Buckling of Piles 142

6.12.5 Mini-piles 143

6.13 DEFORMATION OF SINGLE PILES 143

6.13.1 General 143

6.13.2 Axial Loading 146

6.13.2.1 General 146

6.13.2.2 Load transfer method 146

6.13.2.3 Elastic continuum methods 146

6.13.2.4 Numerical methods 150

6.13.2.5 Determination of deformation parameters 152

6.13.3 Lateral Loading 155

6.13.3.1 General 155

6.13.3.2 Equivalent cantilever method 156

6.13.3.3 Subgrade reaction method 156
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6.13.3.4 Elastic continuum methods 159

6.14 CORROSION OF PILES 160

7. GROUP EFFECTS 165

7.1 G ENERAL 165

7.2 MINIMUM SPACING OF PILES 165

7.3 ULTIMATE CAPACITY OF PILE GROUPS 166

7.3.1 Gene ral 166

7.3.2 Vertical Pile Groups in Granular Soils under Compression 167

7.3.2.1 Free-standing driven piles 167

7.3.2.2 Free-standing bored piles 168

7.3.2.3 Pile groups with ground bearing cap 169

7.3.3 Vertical Pile Groups in Clays under Compression 169

7.3.4 Vertical Pile Groups in Rock under Compression 171

7.3.5 Vertical Pile Groups under Lateral Loading 171

7.3.6 Vertical Pile Groups under Tension Loading 173

7.3.7 Pile Groups Subject to Eccentric Loading 173

7.4 NEGATIVE SKIN FRICTION ON PILE GROUPS 175

7.5 DEFORMATION OF PILE GROUPS 179

7.5.1 Axial Loading on Vertical Pile Groups 179

7.5.1.1 General 179

7.5.1.2 Semi-empirical methods 179

7.5.1.3 Equivalent raft method 180

7.5.1.4 Equivalent pier method 180

7.5.1.5 Interaction factor methods 182

7.5.1.6 Numerical methods 185

7.5.2 Lateral Loading on Vertical Pile Groups 187

7.5.2.1 General 187

7.5.2.2 Methodologies for analysis 187

7.5.2.3 Effect of pile cap 188

7.5.3 Combined Loading on General Pile Groups 190

7.5.3.1 General 190

7.5.3.2 Methodologies for analysis 191

7.5.3.3 Choice of parameters 192

7.6 DESIGN CONSIDERATIONS IN SOIL-STRUCTURE 192

INTERACTION PROBLEMS

7.6.1 Gene ral 192

7.6.2 Load Distribution between Piles 192