Bayardo Materon Bayardo Materon & Associates, Sao Paulo, Brazil

Transcription

1 Concrete Face Rockfill Dams Paulo T. Cruz Dam Consulting Engineer, Sao Paulo, Brazil Bayardo Materon Bayardo Materon & Associates, Sao Paulo, Brazil Manoel Freitas Hydrogeo Engharia SIC Ltda, Sao Paulo, Brazil CRC Press Taylor & Francis Group Boca Raton London New York Leiden CRC Press is an imprint of the Taylor St Francis Croup, an informs business A BALKEMA BOOK

2 - List of figures List of tables Foreword Acknowledgments About the authors Introduction xiii xxiii xxvii xxxi xxxiii xxxv 1 An overall introduction to concrete face rockfill dams I 1.1 A panorama of CFRDs in the world Important events related to CFRD CFRD in seismic areas a historical event High dams in the near future Thoughts on very high CFRDs 10 2 Design criteria for CFRDs Introduction Rockfill embankment Foundation excavation and treatment criteria Zoning designations Rockfill grading and quality Adding water to rockfill Downstream rockfill embankment face Temporary construction slopes and ramps Compaction control tests Water flow through rockfill and leakage Stability Static stability of the rockfill embankment Earthquake considerations Toe slab or the plinth Treatment of the plinth foundation 26

3 vi Dimensions of the plinth Stability of the plinth Layout of the plinth Reinforcing, joints, and anchor bars of the plinth Grouting through toe slab Concrete face slab Concrete Thickness of face slab Reinforcing the slab Perimeter joint Parapet wall and camber Other impervious alternatives Geomembrane Asphalt concrete Construction Instrumentation An overall conclusion 37 3 Typical cross sections International nomenclature Evolution of compacted CFRDs Case histories Cethana (Australia, 1971) Alto Anchicaya (Colombia, 1974) Foz do Areia (Brazil, 1980) Aguamilpa (Mexico, 1993) Campos Novos (Brazil, 2006) Shuibuya (China, 2009) Tianshengqiao 1 (China, 1999) Mohale (Lesotho, 2006) Messochora (Greece, 1996) El Cajon (Mexico, 2007) Karahnjukar (Iceland, 2007) Bakun (Malaysia, 2008) Golillas (Colombia, 1978) Segredo (Brazil, 1992) Xingo (Brazil, 1994) Picbi Picun Leufu (Argentina, 1995) Ita (Brazil, 1999) Machadinho (Brazil, 2002) Antamina (Peru, 2002) Itapebi (Brazil, 2003) 82

4 Machadinho vii Quebra-Queixo (Brazil, 2003) Barra Grande (Brazil, 2005) Hengshan (China, 1992) Salvajina (Colombia, 1983) Puclaro (Chile, 2000) Santa Juana (Chile, 1995) Mazar (Ecuador, 2008) Merowe (Sudan, 2008) Conclusions The mechanics of rockfill Introduction Rockfill embankments evolution The compacted rockfill Rockfills geomechanic properties Intervenient factors Molding problems Shear strength Compressibility Collapse Creep Rockfills as construction materials Some of rockfills used in ECRDs and CFRDs Appendix - Dam Stability Static stability Safety factors for typical rockfills embankments Stability in seismic areas Seismic safety factor Dynamic analysis Seismic design selection Slope stability Permanent deformations Seepage through rockfills Introduction Theories on flow through rockfills Critical aspects for stability Flows Downstream slope stability Critical gradient 167

5 Hengshan viii The effects of anisotropy Discharge Some historical precedents Leakage measured in CFRDs Foundation flows Finite element analysis Anisotropic effects on CFRDs Flow-related conclusions Design of CFRDs for throughflow control Zoning The ideal rockfill Deviations from the "ideal rockfill" Practical recommendations Reinforced rockfill Foundation treatment Plinth foundation Plinth stability Foundation transitions Rockfill foundation River bed On the abutments Grouting Plinth, slab and 201 joints 8.1 Plinth Design concept Width Thickness Plinth-slab connection Features and practices Foundation on deformable structure - case Transversal joints Foundation treatment and regularization Slab Slab design concept New impermeability concepts Slab thickness Joint sealing Reinforcement design Crest parapet wall and freeboard 219

6 ix Fissures, cracks, and failures treatments Drainage near the plinth Instrumentation Introduction Monitoring parameters Dam movements Monitoring rockfill displacements Surface movements Pore pressure Leakage control Slab deflections and strain X stress control Permanent instrumentation houses Monitoring and maintenance care Final considerations CFRD performance Introduction Settlement Correlations between settlement, dam height and valley shape Horizontal displacements Combined movements Face deflection Vertical compressibility modulus and (Ev) transversal modulus (ET) Tri-dimensional displacements Conclusions Numerical analysis and its applications Introduction Engineering properties of rockfill material Rockfill material constitutive models Non-linear elastic model Duncan-Chang's hyperbola model Modified Naylor's K-G model Elasto-plastic model CFRD numerical analyses methods Simulation of surface contact and joints Simulation of construction steps and reservoir impounding sequence 276

7 X 11.5 Application of numerical analyses on CFRDs The contribution of the numerical analyses for improving CFRDs designs Understanding the stress-strain status of the dam Understanding the stress status of face slab Predicting the displacement of joints Case studies Closing remarks Numerical analyses applied to Brazilian CFRDs 290 I 2 Construction features Introduction General aspects Plinth construction Excavation Excavation on sound rock Excavation in weathered rock Excavation in saprolite On alluvium Concrete construction Concrete type Forms type Articulated plinth Diaphragm wall Grouting River diversion Diversion strategy Priority sections Stages Scheduling Embankment construction Types of fill Embankment zoning Fill construction Placing layers Compaction Ramping Dumping under water Stage construction Slab construction Surface preparation Conventional slope protection 323

8 xi Concrete extruded curb Mortar pads Waterstops Mastic Concrete Outputs 332 References 333 Colour plates 341