Structural Foundation Designers' Manual

by Curtin, W. G.; Shaw, Gerry; Parkinson, Gary; Golding, J.; Seward, Norman

• ISBN13: 9781405130448
• ISBN10: 140513044X
• Edition: 2nd
• Format: Hardcover
• Copyright: 2006-12-04
• Publisher: Wiley-Blackwell

Summary

This manual for civil and structural engineers aims to simplify as much as possible a complex subject which is often treated too theoretically, by explaining in a practical way how to provide uncomplicated, buildable and economical foundations.It explains simply, clearly and with numerous worked examples how economic foundation design is achieved. It deals with both straightforward and difficult sites, following the process through site investigation, foundation selection and, finally, design.The book:includes chapters on many aspects of foundation engineering that most other books avoid including filled and contaminated sites mining and other man-made conditions features a step-by-step procedure for the design of lightweight and flexible rafts, to fill the gap in guidance in this much neglected, yet extremely economical foundation solution concentrates on foundations for building structures rather than the larger civil engineering foundations includes many innovative and economic solutions developed and used by the authors' practice but not often covered in other publications provides an extensive series of appendices as a valuable reference source.For the Second Edition the chapter on contaminated and derelict sites has been updated to take account of the latest guidelines on the subject, including BS 10175. Elsewhere, throughout the book, references have been updated to take account of the latest technical publications and relevant British Standards.

Author Biography

Curtins Consulting Engineers is a medium sized firm of structural engineers with 11 offices in the UK. They are well known for their work on foundations and have also authored another book with Blackwell, Structural Masonry Designers’ Manual (0632056126).

Norman Seward, is a chartered engineer and a former Curtin employee. He now lectures at the University of Wales, Newport.

Table of Contents

Preface	p. xi
Preface to First Edition	p. xii
The Book's Structure and What It Is About	p. xiii
Acknowledgements	p. xiv
Authors' Biographies	p. xv
Notation	p. xvi
Approach and First Considerations	p. 1
Principles of Foundation Design	p. 3
Introduction	p. 3
Foundation safety criteria	p. 3
Bearing capacity	p. 4
Introduction	p. 4
Bearing capacity	p. 4
Presumed bearing value	p. 4
Allowable bearing pressure	p. 5
Non-vertical loading	p. 5
Settlement	p. 6
Limit state philosophy	p. 7
Working stress design	p. 7
Limit state design	p. 7
Interaction of superstructure and soil	p. 8
Example 1: Three pinned arch	p. 8
Example 2: Vierendeel superstructure	p. 8
Example 3: Prestressed brick diaphragm wall	p. 8
Example 4: Composite deep beams	p. 9
Example 5: Buoyancy raft	p. 9
Foundation types	p. 9
Pad foundations	p. 10
Strip footings	p. 10
Raft foundations	p. 10
Piled foundations	p. 11
Ground treatment (geotechnical processes)	p. 11
Changes of soil properties during excavation	p. 12
Post-construction foundation failure	p. 12
Practical considerations	p. 13
Example 6: Excavation in waterlogged ground	p. 13
Example 7: Variability of ground conditions	p. 13
Example 8: Reliability of the soils investigation	p. 13
Example 9: Deterioration of ground exposed by excavation	p. 13
Example 10: Effect of new foundation on existing structure	p. 14
Design procedures	p. 14
References	p. 14
Soil Mechanics, Lab Testing and Geology	p. 15
Soil mechanics	p. 15
Introduction to soil mechanics	p. 15
Pressure distribution through ground	p. 15
Bearing capacity	p. 17
Introduction to bearing capacity	p. 17
Main variables affecting bearing capacity	p. 19
Bearing capacity and bearing pressure	p. 19
Determination of ultimate bearing capacity	p. 20
Safe bearing capacity-cohesionless soils	p. 21
Safe bearing capacity-cohesive soils	p. 22
Safe bearing capacity-combined soils	p. 22
Settlement	p. 22
Introduction to settlement	p. 22
Void ratio	p. 23
Consolidation test	p. 23
Coefficient of volume compressibility	p. 24
Magnitude and rate of settlement	p. 25
Settlement calculations	p. 25
Allowable bearing pressure	p. 26
Conclusions	p. 26
Laboratory testing	p. 26
Introduction to laboratory testing	p. 26
Classification (disturbed sample tests)	p. 26
Particle size and distribution	p. 26
Density	p. 27
Liquidity and plasticity	p. 29
General	p. 29
Undisturbed sample testing	p. 29
Moisture content	p. 29
Shear strength	p. 29
Consolidation tests (oedometer apparatus)	p. 29
Permeability tests	p. 32
Chemical tests	p. 32
Summary of tests	p. 32
Analysis of results	p. 37
Final observations on testing	p. 37
Geology	p. 37
Introduction to geology	p. 37
Formation of rock types	p. 38
Weathering of rocks	p. 38
Agents of weathering	p. 38
Temperature	p. 38
Water	p. 38
Wind	p. 38
Glaciation	p. 38
Earth movement	p. 38
Folds, fractures and faults	p. 38
Dip and strike	p. 39
Jointing	p. 39
Drift	p. 39
Errors in borehole interpretation	p. 40
Geophysical investigation	p. 42
Expert knowledge and advice	p. 42
References	p. 42
Ground Investigation	p. 43
Introduction	p. 43
The need for investigation	p. 44
The designer's need	p. 44
The contractor's need	p. 45
The client's need	p. 45
Site investigation for failed, or failing, existing foundations	p. 45
Procedure	p. 45
Site survey plan	p. 47
Study of existing information	p. 47
Preliminary site reconnaissance and site walkabout	p. 47
Soil investigation	p. 48
Borehole layout	p. 48
Trial pits layout	p. 49
Hand augers	p. 50
Boring	p. 50
Backfilling of trial pits and boreholes	p. 50
Soil sampling	p. 50
Storage of samples	p. 50
Frequency of sampling	p. 50
Appointment of specialist soil investigator	p. 51
Site examination of soils	p. 52
Field (site) testing of soils	p. 52
Standard Penetration Test (SPT)	p. 52
Vane test	p. 52
Plate bearing test	p. 53
Pressuremeters	p. 53
Groundwater (piezometers and standpipes)	p. 53
Other field tests	p. 55
Recording information - trial pit and borehole logs and soil profiles	p. 55
Soil samples and soil profiles	p. 56
Preliminary analysis of results	p. 56
Site investigation report	p. 61
Factors affecting quality of report	p. 61
Sequence of report	p. 62
Site description	p. 62
The ground investigation	p. 62
Results	p. 62
Recommendations	p. 62
Fills (made ground)	p. 63
Legal issues	p. 63
Time	p. 64
Conclusions	p. 64
Further information	p. 65
References	p. 65
Special and Further Considerations	p. 67
Topography and its Influence on Site Development	p. 69
Introduction	p. 69
Implications from surface observations	p. 69
Changes in level, ground slopes and movements	p. 69
Mounds, depressions and disturbed ground	p. 70
Past or current activities	p. 71
Vegetation	p. 72
Surface ponding or watercourses	p. 72
Effects on development arising from topographical features	p. 73
Sloping sites	p. 73
Slope stability	p. 75
Groundwater	p. 77
Settlement	p. 78
Summary	p. 79
References	p. 79
Contaminated and Derelict Sites	p. 80
Introduction	p. 80
State of the art	p. 80
Contamination implications	p. 81
Redundant foundations and services	p. 82
Identification	p. 83
Sampling and testing	p. 83
Site treatment	p. 83
Chemical and toxic contamination	p. 83
Part IIA risk-based approach	p. 83
Soil Guideline Values	p. 84
CLEA Model	p. 84
Risk to humans and animals	p. 85
Risks to plants and the wider ecosystem	p. 89
Risk to the water environment	p. 89
Risk to buildings and construction materials	p. 89
Toxic contamination - site identification	p. 91
Contaminant investigation	p. 91
Sampling and testing	p. 92
Site treatment	p. 92
Foundation protection	p. 93
Examples of site investigations on potentially contaminated sites	p. 94
References	p. 94
Mining and Other Subsidence	p. 95
Introduction	p. 95
Mechanics of mining subsidence	p. 95
Methods of mining	p. 97
Longwall workings	p. 97
Pillar and stall workings (partial extraction methods)	p. 97
'Bell-pits'	p. 99
Associated and other workings	p. 100
Abandoned mine shafts and adits	p. 100
Fireclay and other clays	p. 100
Iron ores	p. 100
Other metals	p. 100
Limestone	p. 100
Salt	p. 100
Chalk	p. 100
Faulting	p. 100
Natural and other cavities	p. 100
Dissolving rock	p. 100
Dissolving soils	p. 100
Treatment of abandoned shallow workings	p. 100
Introduction	p. 100
Excavate and backfill	p. 101
Partial and full grouting	p. 101
Treatment of abandoned shafts	p. 101
Capping	p. 101
Effect of mining method and method of treatment	p. 101
Introduction	p. 101
Bell workings	p. 101
Pillar and stall	p. 102
Longwall workings	p. 103
Rafts founded over longwall workings	p. 103
Design principles and precautions in longwall mining subsidence areas	p. 103
Introduction	p. 103
Rafts and strips for low-rise, lightly loading buildings	p. 104
Rafts for multi-storey structures or heavy industrial buildings	p. 105
Jacking points	p. 105
Service ducts	p. 105
Piling	p. 105
Articulated foundation	p. 105
Superstructures	p. 106
Introduction	p. 106
Rigid superstructures	p. 106
Flexible superstructures	p. 106
Monitoring	p. 107
References	p. 107
Fill	p. 108
Filled sites	p. 108
Introduction	p. 108
Movement and settlement	p. 108
The container	p. 108
The container surface	p. 108
The container edges	p. 108
The container base	p. 110
The container sub-strata	p. 110
Water	p. 111
Effect of water on combustion	p. 111
Effect of water on chemical solutions	p. 111
Water lubrication	p. 111
Water inundation	p. 111
Organic decay	p. 111
Information from water	p. 111
The fill material	p. 111
Introduction	p. 111
Fill investigations	p. 112
Special requirements	p. 112
Suggested procedures	p. 113
Settlement predictions	p. 113
Settlement: fill only	p. 113
Settlement: combined effects	p. 115
The development and its services	p. 116
Sensitivity	p. 116
Treatment and solutions	p. 117
New filling for development	p. 118
Case examples	p. 118
Introduction	p. 118
Example 1: Movement of existing building on fill	p. 118
Example 2: New development on existing colliery fill	p. 119
Example 3: New development on new filling	p. 120
Example 4: New developments on existing preloaded fill	p. 120
Example 5: New development on existing backfilled quarry (purchase of coal rights)	p. 121
Example 6: Development on new fill (prevention of flooding)	p. 122
References	p. 123
Further reading	p. 123
Ground Improvement Methods	p. 124
Introduction	p. 124
Surface rolling	p. 124
Introduction	p. 124
Method	p. 124
Soil suitability and variation	p. 125
Site monitoring	p. 125
Vibro-stabilization	p. 126
Introduction	p. 126
Working surfaces	p. 127
Method	p. 127
Vibro-compaction	p. 128
Vibro-displacement	p. 129
Vibro-replacement	p. 129
Summary of vibro-stabilization	p. 130
Design considerations - granular soils	p. 130
Design considerations - cohesive soils	p. 130
Testing	p. 131
Vibro-concrete	p. 131
Dynamic consolidation	p. 133
Introduction	p. 133
Method	p. 133
Usage	p. 133
Site checks	p. 133
Preloading	p. 133
Introduction	p. 133
Method	p. 134
Design of surcharge	p. 134
Installation of drainage systems	p. 134
Grout injections	p. 135
Introduction	p. 135
Loose soils	p. 135
Swallow-holes	p. 136
Shallow mining	p. 136
Mine shafts, wells and bell-pits	p. 136
Lime/cement stabilization	p. 137
Reinforced soil	p. 138
Introduction	p. 138
Foundation applications	p. 139
Patents	p. 139
Research and development	p. 139
Reference	p. 139
Foundation Types: Selection and Design	p. 141
Foundation Types	p. 143
Introduction	p. 143
Foundation types	p. 143
Group one - strip and pad foundations	p. 143
Strip footings	p. 143
Masonry strips	p. 143
Concrete strips - plain and reinforced	p. 144
Concrete trench fill	p. 145
Stone trench fill	p. 145
Rectangular beam strips	p. 145
Inverted T beam strips	p. 145
Pad bases	p. 147
Shallow mass concrete pads	p. 147
Shallow reinforced concrete pads	p. 147
Deep reinforced concrete pads	p. 147
Deep mass concrete pads	p. 147
Balanced pad foundations	p. 148
Rectangular balanced pad foundations	p. 148
Trapezoidal balanced pad foundations	p. 148
Holed balanced pad foundations	p. 148
Cantilever balanced pad foundations	p. 149
Group two - surface spread foundations	p. 149
Nominal crust raft	p. 149
Crust raft	p. 150
Blanket raft	p. 150
Slip-plane raft	p. 151
Cellular raft	p. 151
Lidded cellular raft	p. 151
Beam strip raft	p. 151
Buoyancy (or 'floating') raft	p. 151
Jacking raft	p. 152
Group three-pile foundations	p. 152
Introduction	p. 152
Stone/gravel piles	p. 153
Concrete piles	p. 153
Timber piles	p. 155
Steel piles	p. 156
Anchor piles	p. 156
Anchor blocks	p. 156
Pile caps and ground beams	p. 157
Group four - miscellaneous elements and forms	p. 157
Suspended ground floor slabs	p. 158
Floating ground floor slabs	p. 159
Pier and beam foundations	p. 159
Retaining walls	p. 161
Grillage foundations	p. 162
Foundation Selection and Design Procedures	p. 164
Foundation selection	p. 164
Introduction	p. 164
Foundation selection	p. 164
Information collection/assessment	p. 164
General approach to choice of foundations	p. 165
Questioning the information and proposals	p. 169
Exploitation of foundation stiffness and resulting ground pressure	p. 172
Conclusions	p. 173
Foundation design calculation procedure	p. 173
Introduction	p. 173
Definition of bearing pressures	p. 173
Calculation of applied bearing pressures	p. 174
Structural design of foundation members	p. 178
General design method	p. 180
References	p. 185
Design of Pads, Strips and Continuous Foundations	p. 186
Unreinforced concrete pads and strips	p. 186
Introduction	p. 186
Trench fill	p. 186
Trench fill design decisions	p. 187
Sizing of the design	p. 189
Design Example 1: Trench fill strip footing	p. 190
Design Example 2: Deep mass concrete pad base	p. 192
Unreinforced concrete strips	p. 193
Reinforced concrete pads and strips	p. 194
Introduction	p. 194
Design decisions	p. 194
Sizing up of the design	p. 194
Design Example 3: Reinforced strip foundation	p. 195
Design Example 4: Reinforced pad base	p. 198
Pad foundations with axial loads and bending moments	p. 200
Design Example 5: Pad base - axial load plus bending moment (small eccentricity)	p. 201
Design Example 6: Pad base - axial load plus bending moment (large eccentricity)	p. 202
Design Example 7: Pad base - axial load plus bending moments about both axes	p. 206
Design Example 8: Pad base - axial and horizontal loads	p. 207
Design Example 9: Shear wall base - vertical loads and horizontal wind loads	p. 209
Rectangular and Tee-beam continuous strips	p. 212
Introduction	p. 212
Design decisions	p. 212
Sizing of the design	p. 212
Design Example 10: Continuous Tee beam footing with uniform bearing pressure	p. 213
Design Example 11: Continuous rectangular beam footing with trapezoidal bearing pressure	p. 217
Grillage foundations	p. 221
Introduction	p. 221
Design decisions	p. 221
Sizing of the design	p. 221
Design Example 12: Grillage foundation	p. 221
Floating slabs (ground slabs)	p. 224
Introduction	p. 224
Design decisions	p. 224
Sizing of the slab	p. 225
Design Example 13: Floating slab	p. 225
References	p. 226
Tied and Balanced Foundations	p. 228
General introduction	p. 228
Tied foundations	p. 228
Introduction	p. 228
Design decisions	p. 228
Sizing the foundations	p. 228
Design Example 1: Tied portal frame base	p. 229
Balanced foundations (rectangular, cantilever, trapezoidal and holed)	p. 230
Introduction	p. 230
Design decisions	p. 230
Sizing up the design	p. 230
Design Example 2: Rectangular balanced foundation	p. 232
Design Example 3: Cantilever balanced foundation	p. 233
Design Example 4: Trapezoidal balanced foundation	p. 235
Design Example 5: Holed balanced foundation	p. 236
Raft Foundations	p. 238
Design procedures for semi-flexible rafts	p. 238
Design principles	p. 238
Design of raft layouts	p. 238
Bearing pressure design	p. 239
Design span for local depressions	p. 240
Slab design	p. 240
Beam design	p. 243
Nominal crust raft - semi-flexible	p. 245
Design decisions	p. 245
Sizing the design	p. 245
Design Example 1: Nominal crust raft	p. 249
Crust raft	p. 251
Introduction	p. 251
Design decisions	p. 251
Design Example 2: Crust raft	p. 252
Blanket raft	p. 256
Introduction	p. 256
Design decisions	p. 257
Sizing the design	p. 257
Design Example 3: Blanket raft	p. 257
Slip sandwich raft	p. 261
Introduction	p. 261
Design decisions	p. 262
Sizing the design	p. 262
Design Example 4: Slip sandwich raft	p. 263
Cellular raft	p. 265
Introduction	p. 265
Sizing the design	p. 265
Design Example 5: Cellular raft	p. 266
Lidded cellular raft	p. 270
Introduction	p. 270
Sizing the design	p. 271
Design Example 6: Lidded cellular raft	p. 271
Beam strip raft	p. 271
Introduction	p. 271
Sizing the design	p. 271
Design Example 7: Beam strip raft	p. 272
Buoyancy raft	p. 272
Introduction	p. 272
Sizing the design	p. 274
Design Example 8: Buoyancy raft	p. 274
Jacking raft	p. 276
Introduction	p. 276
Sizing the design	p. 276
References	p. 276
Piles	p. 277
Introduction	p. 277
Applications	p. 277
Types of piles	p. 278
Load-bearing characteristics	p. 278
Materials	p. 278
Methods of piling	p. 283
Driven piles	p. 283
Driven cast-in-place piles	p. 283
Bored cast-in-place piles	p. 283
Screw piles	p. 284
Jacked piles	p. 284
Continuous flight auger piles	p. 284
Mini or pin piles	p. 284
Choice of pile	p. 284
Ground conditions and structure	p. 285
Durability	p. 285
Cost	p. 285
Design of piled foundations	p. 285
Factor of safety	p. 285
Determination of ultimate bearing capacity	p. 286
Pile loading tests	p. 288
Pile groups	p. 288
Spacing of piles within a group	p. 289
Ultimate bearing capacity of group	p. 289
Negative friction	p. 289
Pile caps	p. 289
Introduction	p. 289
The need for pile caps - capping beams	p. 290
Size and depth	p. 290
Design of foundations at pile head	p. 291
Design examples	p. 293
Design Example 1: Calculation of pile safe working loads	p. 293
Design Example 2: Pile cap design	p. 295
Design Example 3: Piled ground beams with floating slab	p. 296
Design Example 4: Piled ground beams with suspended slab	p. 299
Design Example 5: Piled foundation with suspended flat slab	p. 300
References	p. 303
Retaining Walls, Basement Walls, Slip Circles and Underpinning	p. 304
Introduction	p. 304
Retaining walls and basements	p. 304
Stability	p. 305
Flotation	p. 306
Buoyancy	p. 306
Pressures	p. 307
Liquid pressure	p. 307
Earth pressure	p. 307
Surcharge	p. 307
Slip circle example	p. 307
Continuous underpinning	p. 308
Discontinuous underpinning	p. 310
Spread underpinning	p. 311
References	p. 311
Appendices	p. 313
Introduction to appendices	p. 313
Properties and Presumed Bearing Pressures of Some Well Known Engineering Soils and Rocks	p. 314
Map Showing Areas of Shrinkable Clays In Britain	p. 317
Map Showing Areas of Coal and Some Other Mineral Extractions	p. 318
Foundation Selection Tables	p. 319
Guide to Use of Ground Improvement	p. 322
Tables Relating to Contaminated Sites/Soils	p. 325
Factors of Safety	p. 341
Design Charts for Pad and Strip Foundations	p. 343
Table of Ground Beam Trial Sizes	p. 348
Design Graphs and Charts for Raft Foundations Spanning Local Depressions	p. 349
Table of Material Frictional Resistances	p. 357
Cost Indices for Foundation Types	p. 358
Allowable Bearing Pressure for Foundations on Non-Cohesive Soil	p. 359
Index	p. 361
Table of Contents provided by Ingram. All Rights Reserved.