J. A. R. Ortigao . A. S. Sayao

Handbook of Slope Stabilisation

Springer-Verlag Berlin Heidelberg GmbH

J. A. R. Ortigao . A. S. F. J. Sayao

Handbook 01 Siope Stabilisation

With 465 Figures and 53 Tables

Springer

DR. J.A. R. ORTIGAO Terratek Ltd (formerly at the Federal University of Rio de Janeiro) Av Pres Wilson, 165/321 20030-020 Rio de Janeiro, Brazil phone +55-21-25335170 fax +55-21-25332077 ortigao@terratek.com.br www.terratek.com.br

DR. ALBERTO S. SAYAO Departamento de Engenharia Civil Pontifical Catholic University Rua Marques de Sao Vicente, Gavea 22451-041 Rio de J aneiro Brazil

ISBN 978-3-642-07494-3

Cataloging-in-Publication Data

Handbook of slope stabilisation / Alberto Ortigao, Alberto Sayao (editors). p.cm.

Includes bibliographical references and index. ISBN 978-3-642-07494-3 ISBN 978-3-662-07680-4 (eBook) DOI 10.1007/978-3-662-07680-4 1. Slopes (Soil mechanics) - Handbook manuals, etc. 2. Soil stabilization - Handbooks, manuals, etc. I. Ortigao, J.A.R., 1948- H. Sayao, Alberto S.F.J., 1954-

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© Springer-Verlag Berlin Heidelberg 2004 Originally published by Springer-Verlag Berlin Heidelberg New York in 2004 Softcover reprint of the hardcover I st edition 2004

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Preface

This book is aimed at the practising engineer and engineering geologist working in tropical environments, where lands lides are mainly triggered by rain fall. This book is based on a similar work published in 1999 in Portuguese, which became the Rio de Janeiro Slope Manual.

This book is an engineering guide for the design of slopes and stabilisation works in rocks and residual soils. It evolves from the cumulative experience gathered by several engineers and geologists who faced severe slope problems. The authors' experience throughout Central and South America (Costa Rica, Argentina, Bolivia, Peru, Ecuador and Venezuela) and the Far East, especially Hong Kong and Malaysia, was used as a foundation for writing this book.

The work also benefits enormously from the time spent in Hong Kong in 1996 and 1997 by the first editor on sabbatical at the City University of Hong Kong, and the discussions he had with many colleagues from the Geotechnical Engineering Office (GEO) of the Hong Kong Government, especially Dr. A. Malone, Mr. w.K. Pun, Dr. A. Li, Mr. K. Ho, and Mr. y.c. Chan among others.

Many specialists shared their time and expertise with the authors and we would like to thank: Marcio Machado, Ricardo D'Orsi and Wilmar Barros from GeoRio, Mardlio Oliveira, formerly at Este Engineering, Säo Paulo, Roberto Peixoto, formerly at Geotecnica SA, Esther Dantas from Geoflex, Rio de Janeiro, Tony Simmonds from Geokon, USA, Alexandre Texeira, from Maccaferri, Säo Paulo, Dr. Raul Pistone, from Coba Consultants, Portugal, Professor Sergio Saenz from the University of Costa Rica, Professor A. Jeary of the University ofWestern Sydney (formerly at the City University ofHong Kong), Carlos Blanco and Enrique Gajardo from Insitutek Consultores, Venezuela, Professor Mercedes Sierra from the Catholic University of Guaya­quil, Ecuador and Mr. J. MachiaveHo, Minister of Public Works from Ecuador.

Many of the photographs presented here are from the personal files of Mr Ary Maciel, technical photographer at GeoRio, Dr. R. Pistone from Coba Ltd., Portugal, the Hong Kong Geotechnical Engineering Office (GEO), as weH as private companies such as Este Engineering, Sao Paulo, Geoflex, Rio de Janeiro, Geokon, and Maccaferri.

J. A. R. Ortigao, A. S. F. J. Sayao

Contents

1

2

3

Introduction ......... . J.A.R. Ortigao and A.S.J. Sayao

Text Organisation ...... .

Geological Factors in Siope Stability M.A. Kanji

Introduction Basic Rock Mass Structure Inherited from Its Genesis . Intrusive Igneous Rocks Volcanic Rocks . . . Sedimentary Rocks Metamorphie Rocks Weathering Products Significant Geologie Features Geology and the Mode of Failure of a Slope Planar or Two-Dimensional Failure Mode Wedge or Three-Dimensional Analysis Final Remarks References

Landslide Classification and Risk Management J.A.R. Ortigao and M.A. Kanji

Introduction ..... . Landslide Classification Fall Toppie Slides

1

2

5

5 6 6 7 9

12

13 15 19 19 22 24 25

27

27 27 27 29 30

Flow ........... . Rate of Movements . . . . Additional Classifieations Landslide Triggering Meehanisms Creep ...... . El Turi Landslide . . . . . Puriscal Landslide .... A Slope Tale of Two Cities The Laranjeiras Slide and the GeoRio The Po Shan Slide and the GEO . Debris Flow . . . . . . . . . . . . Faetors Influencing Debris Flows Morphology . . . . . . . . . . Rainfall ............. . Suseeptibility of Debris Flows . . Large Debris Flow, Venezuela, 1999 Landslide Description Field Inspeetion Risk Mapping Referenees

4 Site Investigation ............ . J.A.R. Ortigao,A.S.J. Sayao and M.A. Kanji

Introduction .......... Preliminary Site Investigation Landslip Investigation Preliminary Surveying . Auger Boreholes .... Trial Pits and Trenehes Detailed Investigations Topographie Survey .. Geophysical Methods Seismic Method . . . . . Earth Resistivity .... Direet Methods or Boreholes Soundings ..... Percussion Drilling ...... Rotary Drilling ........ Measurement of Drilling Parameters Measurement of Co re Orientation

Contents VII

32 34 34 35 35 35 41 43 46 50 52 52 52 54 55 56 59 59 63 66

67

67 68 69 69 69 70 70 70 70 70 71 72 72 72 72 74 75

VIII Contents

5

Mixed Method Borehole Logs . Block Sampling In Situ Tests Laboratory Testing Characterisation Tests Shear Strength Tests . Typical Strength Parameters for Residual Soils from Rio de Janeiro .............. . Example of Planning Detailed Site Investigation Example of the Soberbo Slide Referenees ......... .

Soil Siope Stability A. S. F. J. Sayao

Introduction ....... . Seope of Stability Analyses Why Landslides OeeuT? .. Types of Stability Analyses Factor of Safety Definition Analysis Teehniques . . Deterministk Methods Limit Equilibrium Stability Charts Example ..... . Infinite Slope . . . Stress-Strain Analysis Probabilistic Methods Slope Stability Analyses Modes of Failure . . . . Input Data ...... . Choke of Method of Analysis Software .. Referenees

75 75 77 78 78 78 78

81 81 84 87

89

89 89 89 90 90 92 92 92 94 97

104 106 106 106 106 106 107 107 108

6 Rock Siope Stability J. A. R. Ortigao

Introduction . FaHure Mechanisms . . . . . . . Graphie Representation of Joints Shear Strength of Rock Joints Shear Strength of Plane Rock Discontinuities Barton Failure Criterion Estimating JRC . . . . . . . . . . . . . . . . . JCS Evaluation ................ . Correction to JRC and JCS Due to Scale Effects Strength of Filled Joints ............ . Effect of Pore pressures ............ . Equivalent Mohr-Coulomb Strength Parameters Backanalysis of Failures Stability Analysis Plan ar Failure Example ..... . Three-Dimensional Wedge Failure Toppling Failure Rockfall .. References

Contents IX

.. 109

109 109 109 114 116 118 119 119 119 123 124 124 124 124 124 127 127 129 131 135

7 Selection of Stabilisation Design ................. 137 J. A. R. Ortigao

Introduction .. . . . . . . . . . . . 137 SoH Slopes . . . . . . . . . . . . 13 7 Slopes with a Rock to SoH Interface 141 Rock Slopes and Rockfall ., . . . . 142 Summary of Stabilisation Methods and Remedial Measures 143

8 Drainage and Surface Protection ................. 147 D. Gerscovich and H. Costa

Introduction ... Hydrologieal Cyde Surface Drainage . Hydraulie Design Maximum Discharge

147 147 150 153 153

X Contents

Catchment Area ..... Average Rainfall Intensity Runoff Coefficient .... Admissible Flow Velo city Flow Regime .... . Flow Velocity .... . Calculation Procedure Freeboard ...... . Example of Hydraulic Design Design of Surface Drainage Systems General Considerations Drainage Devices . . . . . . . . . . . Slope Ditches ............ . Downslope Channels, Stepped Channels Ca tchpits ...... . Dumping Basins .. . Subsurface Drainage Horizontal Drains .. Cut -off Drains .... Granular Filters and Drains Geosynthetics . . . Drainage Trenches Drain Blanket . . . Relief Wells . . . . Retaining Wall Drainage Systems Drainage ofVery Large Slopes Maintenance Works Surface Protection Vegetation Grass ..... . Trees and Shrubs Geomembranes . Impermeable Surface Soil-Cement-Lime Mixture (Chunam) Sprayed Concrete (Shotcrete) Blocks ................. . Debris-Flow Proteetion Works ... . Works for Restricting the Occurrence of Debris Flows Slope Supporting Dams and Stepped Check Dams .. Debris-Flow Capturing Works or Sabo Dams ..... Sediment Control Dams and Reservoirs or Debris-Flow Depositing Works .................... .

154 154 156 157 157 159 159 161 163 165 165 167 168 170 171 174 175 176 180 181 182 186 186 188 188 194 194 195 198 198 199 199 201 203 204 204 204 205 205 206

207

Downstream Control-works ..... . Diverting and Deflecting Works ... . Example . . . ... . References ............... .

Contents XI

207 209 209 209

9 Retaining Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 A. S. F. J. Sayao

Introduction Earth Pressures Active and Passive States Rankine Method . . . . . . . . . Coulomb's Theory ....... . Groundwater Effect ............ . Stability of Walls . . . . . . . . . . . . . . Global or Generalised Stability ..... . Slipping at the Base of a Wall ...... . Check for Overturning . . . . . . Check on the Bearing Capacity . . . . . . Reinforced Concrete Walls ....... . L-Shaped Walls . . . . . . . . . . . . . . . Walls with Ground Anchors at the Base . Rock Dowelled Concrete Walls ..... . Gravity Walls . . . . . . . . . . . . . . . . Masonry Walls ......... . Unreinforced Concrete Walls .. Gabion Walls .......... . Scrap Tyre Wall . . . . . . . . . . . . . . Cement Bags for Slope Failure Rehabilitation Reinforced Earth Walls . . . . . . References .................. .

213 213 214 216 217 223 223 224 225 225 227 228 229 229 230 232 232 233 233 236 237 240 241

10 Geosynthetic Reinforced Walls and Siopes ........... 243 E. M. Palmeira

Introduction .. Geosynthetic Relevant Properties .... Introduction .......... . Design Parameters . . . . . . . . Soil-Related Parameters .....

243 246 246 250 250

XII Contents

Geosynthetic Mechanical Properties ........... 251 Design of Geosynthetic Reinforced Walls ........ 254 Stability Conditions for Geosynthetic Reinforced Walls 254 External Stability . . . . . . . . . . . . . . . . 254 Sliding of the Reinforced Mass Along Its Base ...... 256 Stability Against Wall Overturning . . . . . . . . . . . . 257 Vertical Stress Distribution on the Wall Base and Foundation Soil-Bearing Capacity .. 258 Overall Stability ..... 260 Internal Stability Analysis 260 Reinforcement Spacing . . 261 Reinforcement Anchorage Length 264 Localised Surcharge and Compaction 269 Horizontal Displacements of the Wall Face 272 Other Design Approaches . . . . . . . 277 Geosynthetic-Reinforced Steep Slopes 278 Earth Pressure Calculation ...... 278 Design Charts by Jewell (1989) .... 279 Vertical Stresses on the Slope Base and Foundation Soil Bearing Capacity ...................... 284 Overall Stability .................. 286 Construction of Geosynthetic Reinforced Walls and Steep Slopes . . . . 286 Facing of the Structure ........... 286 Drainage Systems . . . . . . . . . . . 295 Handling and Storage of the Geosynthetics 297 Worked Example . . . . . . . . . 297 Soils . . . . . . . . . . . . . . . . 298 Foundation Soil (Design Values) 298 Reinforcement .......... 298 External Stability . . . . . . . . . 299 Earth Thrust and Active Stresses Along the Rear Face of the Wall . . . . . . . 299 Sliding Along the Base . . . . . . . . . . . . . . . . . 299 Wall Overturning . . . . . . . . . . . . . . . . . . . . 300 Distribution of Vertical Stresses on the Wall Base and Foundation Soil-Bearing Capacity ...... 300 Internal Stability . . . . . . . . . 302 Reinforcement Design Properties 302 Reinforcement Spacing . . . . . . 302 Reinforcement Anchorage Length 304 Reinforcement Anchorage at the Wall Face 305

Evaluation of Expected Maximum Wall Face Horizontal Displacement

References . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents XIII

306 309

11 Anchors, Bolts and Nails ...................... 311 J. A. R. Ortigao and H. Brito

Introduction ....... . Anchors .......... . Recommended Anchor Characteristics Materials Grout . Grease .. Plastics . Strain Compatibility of the Bonded Length Protection Anchor, Bolts and NaH Types Test and Working Loads Installation Drilling ........ . Grouting ....... . Pull-out Capacity of the Bonded Length Soil Anchors ... Rock Anchors Anchor Load Tests Definitions ... Pull-out Tests . . Load Application Test Set-up Criterion for Starting the Tension Load Test Safety Criterion . . . . . . . . Load Measurement . . . . . . Displacement Measurements Interpretation of the Results Acceptance Criteria .... . Results Interpretation ... . Interpretation of Pull-out Test on Nails Bolts and NaHs . . . . . . . . . . . . Corrosion Protection ....... . Final Protection to the Anchor Head References

311 311 311 314 314 315 315 315 317 317 318 318 319 319 319 321 321 321 322 323 323 323 323 323 324 324 325 325 325 327 327 328 329

XIV Contents

12 Tieback Walls ...................... 331 J. A. R. Ortigao and H. Brito

Introduction ....... . Stability Analysis .... . Stability Analysis Methodology Wedge Method . . . . . . . . . . Pre-design Charts ....... . Stability Analysis of Complex Cases Anchor Spacing .......... . Error in Plane Strain Assumption . Tieback Walls Supported by Micropiles Worked Example of Tieback Wall Design Stresses and Deformation Analysis ~furenc~ ................ .

331 334 337 337 339 343 344 344 345 345 350 352

13 Soil Nailing .............................. 355 J. A. R. Ortigao and E. M. Palmeira

Introduction ................. 355 Origin . . . . . . . . . . . . . . . . . . . . . 355 Experience in Residual and Saprolitic Soils 356 Construction Methods and Soil Nailing Application 356 Installation ofNails 357 Nail Head Details ........ 359 The Slope Facing . . . . . . . . . 359 Comparison with Tieback Walls 361 Comparison with Reinforced Walls 363 Advantages of Soil Nailing 364 Limitations of Soil Nailing ..... 365 Examples of Soil Nailing ...... 365 35-m-High Wall at Icarai Beach, Niter6i, RJ 365 Slope Stabilisation in Phyllite at the Abutment of a Railway Bridge 366 Retrofitting of Slopes in Hong Kong 367 Analysis of SoH Nailed Structures .... 367 SoH-naH Interaction . . . . . . . . . . . . 372 Limit Equilibrium and the Effect ofNails 373 Computer Programs . . . . . . . . . . . . 374 Design Optimisation ........... 377 Analysis of Mixed Soil Nailed Structures 379 Stability Charts .............. 381

Deformation Analysis . . . . . . Stability Analysis Through FEM ~fureK~ ........... .

Contents XV

381 385 386

14 Stabilisation of Rock Siopes .................... 389 J. A. R. Ortigao and H. Brito

Introduction ............... 389 Techniques to Prevent Block Move-out 390 Risk Reduction Measures 398 Protective Wire Mesh .......... 400 Flexible Barriers . . . . . . . . . . . . . 400 Design of Anchors and Bolts for Rock Block Stabilisation 406 Design of Bolts as Dowels . . . . . . . 408 Design of Bolts for Tension and Shear 409 Design Charts 411 Example . . 412 References 412

15 Shotcrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413 M. Carnio and J.A.R. Ortigao

Introduction ........ . Shotcrete Reinforcement ................ . Performance of SFRS (Steel Fibre Reinforced Shotcrete) Definitions and Composite Materials Fibres as Reinforcement Elements Toughness ..... . Equivalent Strength Toughness Ratio .,. Design with SFRS .. Stress Distribution in the Cross Section Example ..... . Fibre Type Selection . . . Example ........ . Concrete Characteristics Equivalent Strengths Fibre Rebound References

413 415 417 417 418 418 419 419 419 420 421 421 422 422 422 423 423

XVI Contents

16 Instrumentation ........................... 425 J.A.R.Ortigao

Introduction . Quantities to be Measured Instruments Rain Gauges Piezometers . Casagrande Piezometer Casagrande Piezometer Installation In Situ Permeability ..... . Advantages and Disadvantages Observation Weil . . . . . . Vibrating Wire Piezometers Advantages ofVW Sensors Disadvantages ..... Surge Protection Piezometer Installation Inclinometers . . . . . . Inclinometer Access Tube Installation The Inclinometer Sensor . . . . . . . LoadCelli .............. . Surveying Ground Surface Displacements Example of Automatie Monitoring of a Specific Slope Geology and Soil Profile Instrumentation Piezometers . . . . . . . The Cliper ...... . Data Acquisition and Software Software ............ . Results Vibrating Wire In-Place Inclinometers Alarm Systems Concepts The Rain Gauge Network Software ......... . Homepage ....... . Critical Precipitation Levels Weather Forecast . . . . . . Regional Scale Analysis .. Meteorologieal Doppler Radar Alaaaaaarm .. . ........ . Data Integration Between Radar and Rain Gauges References ..................... .

425 425 425 426 426 427 427 428 429 430 431 433 434 434 435 435 438 439 441 443 444 444 446 446 447 449 449 449 452 452 454 455 455 455 457 458 461 462 464

464

Authors

BETO ORTIGAO is Associate Professor at the Federal University of Rio de Janeiro, Brazil. He received his first degree in Civil Engineering in 1971, followed by a Ph.D. in 1980. From 1982 to 1984, he worked on offshore foun­dations at the Building Research Establishment in the UK and on offshore foundation design at Fugro UK Ltd. In 1991, he was Visiting Associate Pro­fessor to the UniversityofBritish Columbia (UBC). In 1996 and 1997,he was Visiting Fellow to the City University of Hong Kong. In 1998, he received a grant from the Association of Universities and Colleges of Canada AUCC and visited UBC again for 1 month. He has been involved in severallarge projects in Brazil and overseas involving: slope stabilisation, embankments on soft soils, offshore foundations, pipelines, harbours and tunnelling.

His research interests inc1ude in situ testing, instrumentation, soil rein­forcement and tunnelling, on which he has over 90 publications. He authored a textbook, Soil Mechanics in the Light of Critical State Theories, published by Balkema in 1995. He has lectured worldwide: in the Far East (Hong Kong and Malaysia), Europe (UK, France, Portugal) and South and North America.

He is a member of the ABMS, the Brazilian Society of Soil Mechanics, the ISSMFE, the International Society of Soil Mechanics and Foundation Engineering and the Engineering Club of Rio de Janeiro and is also a very proud member of the Flamengo Masters Swimmers Club.

ALBERTO SAYAO is Associate Professor at the Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Brazil. He received his B.Sc. degree in Civil Engineering in 1976, followed by his M.Sc. in 1980 at PUC-Rio. He completed his Ph.D. in 1989 at The University of British Columbia, Canada. He visited and cooperated with several research centres such as the universities of Ottawa and British Columbia in Canada, Cedex in Spain, and Furnas in Brazil.

He has been involved in severallarge projects on slope stabilisation, con­struction on soft soils, harbours, offshore breakwaters, and earth and rock -fill dams. His research interests inc1ude slope stability, soil reinforcement and soil behaviour from laboratory and in situ testing, on which he has published

XVIII Authors

over 30 publications. He also co-authored with Dr. Ortigao the 700-page text, Technical Manual on Slopes, published in 1999 by GeoRio (the Geotechnical Engineering Office in the city of Rio de Janeiro).

He was invited for severallectures and seminars in South America (Brazil, Paraguay), North America (Canada and USA), Central America (Costa Rica) and Europe (Spain, Portugal). He is an active member of several engineering societies, such as the Brazilian Society of Soil Mechanics (ABMS), the Inter­national Society of Soil Mechanics and Geotechnical Engineering (ISSMGE), the Canadian Geotechnical Society (CGS) and the Engineering Club of Rio de Janeiro.

MILTON KAN]I is Associate Professor at the Polytechnic School of the Uni­versity of Säo Paulo, Brazil. He completed his studies in geology in 1960 and obtained his M.Sc. degree at the University of Illinois in 1970, and his Ph.D. at the University of Sao Paulo in 1973.

Dr. Kanji has been active in the industry. At Prornon Engenharia S.A., as head of the Rock Mechanics Division, he was responsible for outstanding works such as the foundation design of the Itaipu and Agua Vermelha dams, the Coolant Tunnel of the Angra Nuclear Power Plant, design of the final slopes of the open pit Caue Mine and many others. At Geotecnica S.A., he was head of the international branch and supervised the stabilisation of the penstock slope of the Gera Power Plant and the stabilisation of the port of Iquitos river banks in Peru).

At the University of Sao Paulo, he investigated debris flow risk and designed protection works for the Cubatäo refinery plant. He also carried out risk evaluation for the Bolivia-Brazil gas pipeline. Dr Kanji has lectured internationally and published over 60 technical papers. He has served the engineering community as past Vice-President for South America of the ISRM and as past President of the Brazilian Committee on Rock Mechanics. Presently, he is a member of the new Joint Technical Committee on Land­slides (ISSMGE, ISRM and IAEG).

ENNIO PALMEIRA is Associate Professor at the University of Brasilia, Brazil. He received his B.Sc. and M.Sc. in Civil Engineering in 1977 and 1981 from the Federal University of Rio de Janeiro. He holds a Ph.D. degree in Civil Engineering from the University of Oxford, UK (1987). Both his master and doctoral theses dealt with soil reinforcement and the use of geosynthetics in geotechnical engineering.

In 1995, he was Visiting Associate Professor to the University of British Columbia (UBC), researching geosynthetics. He has acted as an inde­pendent consultant in projects involving soil reinforcement, geosynthetics in geotechnical engineering, slope stabilisation, drainage systems and em-

Authors XIX

bankments on soft soils as well as being a member of advisory committees for governmental bodies for education, training and research in Brazil and Australia.

His research interests include soil reinforcement and geosynthetic appli­cations in geotechnical and environmental engineering, on which he has over 100 publications. In 1996, he was awarded the "IGS Award" by the International Geosynthetics Society, for his contribution to the study and applications of geosynthetics. In 1999, he received the ''Academic Excellency Award" from the Association of the Professors of the University of Brasilia. He is a member of the council of the International Geosynthetics Society and chairperson of the South American Committee of the same society. He is also a member of the Brazilian Society of Soil Mechanics, the International Geosynthetics Society, the British Geotechnical Society, the International Society of Soil Mechanics and Foundation Engineering and has been a hard working amateur classical guitarist for the last 30 years.

DENISE GERSCOVICH is Associate Professor at the State University of Rio de Janeiro, Brazil. She received her B.Sc. degree in Civil Engineering in 1979, her M.Sc. degree in Geotechnical Engineering in 1983, followed by a D.Sc. in 1994. From 1990 to 1991, she was Visiting Associate Professor at the Univer­sity of British Columbia (UBC) in the graduate »sandwich« programme.

She worked on the development of laboratory instrumentation for stress monitoring in a plane strain apparatus and the development of finite element codes to simulate soil-concrete joints and flow-through porous media. Her particular research interest focuses on studies of slope instability mecha­nisms and remedial measures.

She wrote a 3D finite element code to simulate transient flow processes through unsaturated soil media. She also investigated the use of scrap tyres as a non-conventional soil reinforcement element or as a civil engineering material to build gravity retaining walls.

Currently, she is working on the analysis of the deformability of nailed soil-retaining structures. Her research interests also include in situ testing, embankments on soft soils and dams. She has been involved in severallarge projects including slope stabilisation and consolidation of solid disposal. She is a member of the ABMS, the Brazilian Society of Soil Mechanics, the ISSMFE, the International Society of Soil Mechanics and Foundation Engineering.

HELDER COSTA graduated in Civil Engineering in 1971 and received his M.Sc. in 1983 from the Federal UniversityofRio de Janeiro. He attended spe­cial courses on hydrology, water resources and environmental engineering in America, Japan, Sweden and France.

xx Authors

As a civil servant of the State of Rio de Janeiro, he occupied outstanding positions that included: President of the Environmental Protection Authority, President of the Mineral Resources Department, President of the Lagoons and Rivers Authority, Technical Advisor of the Committee for De-pollution of the Guanabara Bay. He also worked as an independent consultant on hy­drology and water resources for many outstanding projects in Brazil and South America.

HELIO BRITO was Head of the Design Section of GeoRio, the Rio de Janeiro Geotechnical Institute from 1996 to 2000 and is currently Assessor to the Director of GeoRio. He received his B.Sc. in Civil Engineering from the Federal University of Rio de Janeiro in 1976 and took several post-gradua­tion courses on geotechnical engineering, geoprocessing and risk analysis at the same university.

He has been involved in over 300 slope stabilisation projects throughout Brazil. He designed one of the highest tieback walls in Brazil, 26 m high, in residual soils and the 200-m-high pit slopes for the iron ore mines of Timbopeba and Caue Mines and worked on the monitoring of these slopes for 8 years.

His work at GeoRio led hirn to participate in projects including: the Covanca Tunnel and slopes of the Yellow Line, stabilisation works for squatter areas, an underground garage at Cinelandia square, shore protection works in Rio de Janeiro, among others. He is also a member of the Brazilian Geot­echnical Society and the Engineering Club of Rio de Janeiro.

MARCO CARNIO is a specialist in reinforced concrete and materials. He re­ceived his B.Sc. in 1986 and his M.Sc. in 1998 from Unicamp University of Campinas, Säo Paulo, Brazil, and is currently working towards a Ph.D. at the University of Sao Paulo. He teaches reinforced concrete at the Pontifical Catholic University of Campinas. He is an active consultant engineer in his field and a specialist in fibre-reinforced shotcrete. He has worked on many projects in Brazil and has lectured short courses in Brazil and other South American countries. He is a member of the Ibracon, the Brazilian Concrete Institute.