DAMS AND APPURTENANT HYDRAULIC STRUCTURES

rs-t DAMS AND APPURTENANT HYDRAULIC STRUCTURES LJUBOMIR TANCEV Professor, Faculty of Civil Engineering, Sts Cyril and Methodius University, Skopje, Republic of Macedonia A.A. BALKEMA PUBLISHERS LEIDEN / LONDON / NEW YORK / PHILADELPHIA / SINGAPORE

Contents Preface xiii PART ONE: DAMS AND APPURTENANT HYDRAULIC 1 STRUCTURES - GENERAL 1 UTILIZATION OF WATER RESOURCES BY MEANS OF HYDRAULIC 3 STRUCTURES 1.1 Introduction 3 1.2 Hydraulic structures (definition, classification) 6 1.3 General features of hydraulic structures 7 1.4 Intent of dams. Elements of a dam and a reservoir 16 1.5 Short review of the historical development of hydraulic structures 17 2 FOUNDATIONS OF DAMS 19 2.1 Foundations for hydraulic structures in general 19 2.2 Requirements for the foundation 22 2.3 Investigation works regarding dam foundations 30 2.4 Improvement of foundations 32 3 SEEPAGE THROUGH DAMS 43 3.1 Action of seepage flow 43 3.2 Mechanical action of seepage flow on the earth's skeleton 44 3.3 Seepage resistance of earth foundations and structures 47 3.4 Theoretical aspects of seepage 48 3.5 Practical solution of the problem of seepage 53 3.6 Seepage in anisotropic soil conditions 57 3.7 Seepage in non-homogeneous soil conditions 60 3.8 Seepage of water through rock foundations 61 3.9 Lateral seepage 64 3.10 Seepage through the body of concrete dams 65 4 FORCES AND LOADINGS ON DAMS 67 4.1 Forces and loadings on dams in general 67 4.2 Forces from hydrostatic and hydrodynamic pressure 69 4.3 Influence of cavitation and aeration on hydraulic structures 71 4.4 Influence from waves 72 4.5 Influence of ice and water sediment 79 4.6 Seismic forces 81 4.7 Temperature effects 84 4.7.1 Temperature effects on embankment dams 85 4.7.2 Temperature effects on concrete structures 86

vi CONTENTS 5 DESIGNING HYDRAULIC STRUCTURES 89 5.1 Basic stages in the process of the creation and use of hydraulic structures 89 5.2 Investigation for design and construction of hydraulic structures 90 5.3 Contents of the hydraulic design and design phases 93 5.4 Project management and the role of legislation 97 PART TWO: EMBANKMENT DAMS 101 6 EMBANKMENT DAMS - GENERAL 103 6.1 Introduction, terminology, and classification 103 6.2 Historical development of embankment dams 107 6.3 Dimensions of the basic elements of embankment dams 110 6.4 Choice of the dam site H5 6.5 Materials for construction of embankment dams 116 6.6 Choice of type of embankment dam 119 6.7 Tailings dams 125 7 SEEPAGE THROUGH EMBANKMENT DAMS 129 7.1 Kinds of seepage through the embankment dam body 129 7.2 Seepage line and hydrodynamic net in embankment dams 131 7.3 Measures against the harmful effect of seepage 135 7.3.1 Action against local seepage rising 136 7.3.2 Action against external erosion 137 7.4 Calculations of the casual seepage strength of earthfill dams 142 8 STATIC STABILITY OF EMBANKMENT DAMS 145 8.1 Introduction 145 8.2 Classical methods 145 8.2.1 Method of slices 146 8.2.2 Wedge method 150 8.2.3 States in which stability of embankment dams is examined 151 8.2.4 Stability of rockfill dams 157 8.3 Contemporary methods 158 8.3.1 Application of the Finite Element Method 15 8 8.3.2 Specific properties of the application of the Finite Element Method 161 (FEM) for analysis of embankment dams 8.3.3 Choice of constitutive law 162 8.3.4 Simulation for dam construction in layers 171 8.3.5 Simulation for filling the reservoir and the effect of water 174 8.3.6 Simulation of behavior at the interfaces of different materials 181 8.3.7 Analysis of consolidation 186 8.3.8 Creep of materials in the body of embankment dams 192 8.3.9 Three-dimensional analysis 195 9 DYNAMIC STABILITY OF EMBANKMENT DAMS 197 9.1 Effect of earthquakes on embankment dams 197 9.2 Assessment of design earthquake 199

CONTENTS VII 9.2.1 Strength, attenuation, and amplification of earthquakes 199 9.2.2 Design earthquake 203 9.3 Liquefaction 205 9.4 Analysis of stability and deformations in embankment dams induced 207 by earthquakes 9.4.1 Pseudo-static method 208 9.4.2 Pseudo-static methods with a non-uniform coefficient 209 of acceleration 9.4.3 Equivalent linear method 215 9.4.4 Pure nonlinear method 215 10 EARTHFILL DAMS 221 10.1 Classification and construction of earthfill dams 221 10.2 Structural details for earthf ill dams 222 10.2.1 Slope protection 222 10.2.2 Water-impermeable elements 228 10.2.3 Drainages 235 10.3 Preparation of the foundation and the joint between earthfill dams 243 and the foundation 10.3.1 Preparation of the general foundation 244 10.3.2 Preparation of the foundation when using a dam cutoff trench 244 10.3.3 Joint of the earthfill dam and the foundation 244 11 EARTH-ROCK DAMS 249 11.1 Construction of earth-rock dams 249 11.2 Earth-rock dams with vertical core 252 11.3 Earth-rock dams with a sloping core 255 11.4 Earth-rock dams of'soft'rocks 260 11.5 Fissures in the core of earth-rock dams 263 11.5.1 Kinds of fissures and causes for their occurrence 263 11.5.2 Measures for preventing the occurrence of fissures 266 11.6 Designing earth-rock dams in seismically active areas 272 12 ROCKFILL DAMS WITH REINFORCED CONCRETE FACING 275 12.1 Definition, field of application and construction 275 12.2 Modern dams with reinforced concrete facing 281 12.3 Joints for reinforced concrete facings 289 12.4 Construction of reinforced concrete facings 294 12.5 Examples of modern dams with reinforced concrete facing 296 13 ROCKFILL DAMS WITH ASPHALTIC CONCRETE AND OTHER 303 TYPES OF FACINGS 1 Rockfill dams with asphaltic concrete facing 303.1 General characteristics 303.2 Composition and characteristics of hydraulic asphaltic concrete 304.3 Construction of the asphaltic concrete facings 306.4 Joint of the lining with a gallery or concrete cutoff in dam's toe 312.5 Joint of the facing with dam's crest 317

viii CONTENTS 2 Rockf ill dams with steel facing 3 Rockfill dams with facing of geomembrane 320 14 ROCKFILL DAMS WITH DIAPHRAGM WALL 327 14.1 Rockfill dams with asphaltic concrete diaphragm wall 327 14.1.1 Function, conditions of work and materials 327 14.1.2 Structure of the asphaltic concrete diaphragm walls 329 14.1.3 Joint of diaphragm wall with the foundation and lateral 335 concrete structures 14.2 Other types of diaphragm walls 339 14.2.1 Concrete diaphragm walls 339 14.2.2 Grout and plastic diaphragm walls 345 14.3 Stability of earth-rock dams with diaphragm wall 346 15 MONITORING AND SURVEILLANCE OF EMBANKMENT DAMS 351 15.1 Task and purpose of monitoring 351 15.2 Monitoring of pore pressure and seepage 352 15.2.1 Hydraulic piezometers 352 15.2.2 Electric piezometers 355 15.2.3 Monitoring of seepage 356 15.3 Monitoring of displacements 358 15.3.1 Measurement of displacements at the surface of the dam 358 15.3.2 Measuring displacements in the interior of the dam 359 15.4 Measurements of stresses 367 15.5 Seismic measurements 367 15.6 General principles on the selection and positioning layout of measuring 368 instruments PART THREE: CONCRETE DAMS 373 16 GRAVITY DAMS ON ROCK FOUNDATIONS 375 16.1 Gravity dams in general 375 16.2 Mass concrete for dams 377 16.2.1 General 377 16.2.2 Constituent elements of mass concrete 377 16.2.3 Parameters of concrete mixture 378 16.2.4 Fabrication and placing of concrete 379 16.3 Cross-section of gravity dams 379 16.3.1 Cross-sections in general 379 16.3.2 Theoretical cross-section 381 16.3.3 Practical cross-section 384 16.4 Dimensioning of concrete gravity dams 387 16.4.1 Elementary methods 387 16.4.2 Modern methods 389 16.5 Determination of stresses 391 16.5.1 Determination of stresses by the gravitational method 391 16.5.2 Calculation of stresses by using the theory of elasticity 395 3J8

CONTENTS IX 16.5.3 Influence of temperature changes, shrinkage and expansion of 397 concrete on stresses in dams 16.5.4 Permissible stresses and cracks 398 16.6 General structural features of gravity dams 399 16.7 Stability of gravity dams on rock foundation 410 16.7.1 Dam sliding and shearing across foundation 411 16.8 Hollow gravity dams 415 17 GRAVITY DAMS ON SOIL FOUNDATIONS 419 17.1 Fundamentals of gravity dams on soil foundation 419 17.2 Schemes for the underground contour of the dam 421 17.3 Determination of basic dimensions of underground contour 423 17.4 Construction of elements of the underground contour 424 17.5 Construction of the dam's body 429 17.6 Dimensioning and stability of gravity dams on soil foundation 437 18 ROLLER-COMPACTED CONCRETE GRAVITY DAMS 441 18.1 Introduction 441 18.2 Characteristics of roller-compacted concrete 443 18.3 Types of roller-compacted concrete 445 18.4 Trends in development of dams made of roller-compacted concrete 446 18.5 Improving the water-impermeability of dams made of roller-compacted 448 concrete 18.6 Cost of dams made of roller-compacted concrete 450 18.7 Examples of dams made of roller-compacted concrete 452 18.8 Particularities of high dams of roller-compacted concrete 469 19 BUTTRESS DAMS 473 19.1 Definition, classification and general conceptions 473 19.2 Massive-head buttress dams 475 19.3 Flat-slab buttress dams 479 19.4 Multiple-arch buttress dams 485 19.5 Conditions for application of buttress dams 492 20 ARCH DAMS 497 20.1 Arch dams in general - classification 497 20.2 Development of arch dams through the centuries 500 20.3 Methods of designing arch dams 505 20.3.1 Basic design 505 20.3.2 Arch dams with double curvature 511 20.3.3 Form of arches in plan and adaptation to ground conditions 520 20.4 Structural details of arch dams 524 20.5 Static analysis of arch dams 529 20.5.1 Method of independent arches 529 20.5.2 Method of central cantilever 534 20.5.3 The Trial-Load Method 537

x CONTENTS 20.5.4 The Finite Element Method 20.5.5 The Experimental Method 539 21 DYNAMIC STABILITY OF CONCRETE DAMS 543 21.1 Earthquake effects on concrete dams 543 21.2 Methods for dynamic analysis of concrete dams 544 21.2.1 Linear analysis and response of the structure 546 21.2.2 Nonlinear analysis and the response of the dam 547 21.3 Knowledge gained from practice and experiments 550 22 MONITORING AND SURVEILLANCE OF CONCRETE DAMS 553 22.1 Monitoring, surveillance, and instrumentation of concrete dams - 553 general 22.2 Monitoring by precise survey methods 554 22.3 Surveillance with embedded instruments 557 22.4 Automatization and computerization of monitoring 562 538 PART FOUR: HYDROMECHANICAL EQUIPMENT AND APPURTENANT 565 HYDRAULIC STRUCTURES 23 MECHANICAL EQUIPMENT AND APPURTENANT 567 HYDRAULIC STRUCTURES - GENERAL 23.1 Hydromechanical equipment - general 567 23.1.1 Introduction 567 23.1.2 Classification of gates and valves 568 23.1.3 Forces acting on gates and valves 568 23.2 Mechanisms for lifting and lowering of the gates and valves. Service 569 bridges 23.3 Installation and service of gates and valves 571 23.4 Appurtenant hydraulic structures 573 23.4.1 Definition, function, and capacity 573 23.4.2 Classification of spillways and bottom outlets 575 23.5 Evacuation of overflowing waters via a chute spillway 577 23.6 Energy dissipation of the spillway jet 581 23.7 Selection of type of spillway structure 589 24 SURFACE (CREST) GATES 591 24.1 Basic schemes of surface (crest) gates 591 24.2 Surface (crest) gates transferring water pressure to side walls or piers 593 24.2.1 Ordinary plain metal gates 593 24.2.2 Special plain gates 599 24.2.3 Stop-log gates 600 24.2.4 Radial gates 601 24.2.5 Roller gates 606 24.3 Surface (crest) gates transferring the water pressure to the gate sill 610 24.3.1 Sector (drum) gates 611 24.3.2 Flap gates 613

CONTENTS XI 24.3.3 Bear-trap gates 614 24.3.4 Inflatable gates 616 25 HIGH-HEAD GATES AND VALVES 619 25.1 General characteristics - classification 619 25.2 High-head gates transferring pressure to the structure directly through 621 their supports 25.2.1 Plain high-head gates 621 25.2.2 Radial (taintor) high-head gates 625 25.2.3 Diaphragm gate 628 25.3 Valves transferring the pressure through the shell encasing the valve 631 25.3.1 Waterworks valve types 631 25.3.2 Disc-like or butterfly valves 633 25.3.3 Cone dispersion valve 634 25.3.4 Needle valves and spherical valves 635 25.4 Cylindrical balanced high-head valves 636 26 SPILLWAYS PASSING THROUGH THE DAM'S BODY 637 26.1 Crest spillways 637 26.2 High-head spillway structures 645 27 SPILLWAYS OUTSIDE THE DAM'S BODY 653 27.1 Frontal (ogee) spillway structure 653 27.2 Side-channel spillway 661 27.3 Shaft (morning glory) spillway 668 27.4 Siphon spillways 680 28 BOTTOM OUTLET WORKS 685 28.1 Basic assumptions on designing bottom outlet works 685 28.2 Bottom outlet works in concrete dams 686 28.3 Bottom outlet works in embankment dams 688 29 SPECIAL HYDRAULIC STRUCTURES 697 29.1 Transport structures 697 29.2 Hydraulic structures for the admission and protection of fish 701 30 RIVER DIVERSION DURING THE CONSTRUCTION OF 709 THE HYDRAULIC SCHEME 30.1 River diversion during the construction of dams and appurtenant 709 hydraulic structures - general 30.2 Construction of the structures without river diversion from the parent 710 river channel 30.2.1 Method with damming of the construction (foundation) pit 710 30.2.2 Method without damming of the construction pit 714 30.3 Construction of the structures with river diversion from the river channel 716

XII CONTENTS PART FIVE: HYDRAULIC SCHEMES 719 31 COMPOSITION OF STRUCTURES IN RIVER HYDRAULIC SCHEMES 721 31.1 Definition and classification of hydraulic schemes 721 31.2 General conditions and principles for the composition of hydraulic schemes 722 31.3 Characteristics of river hydraulic schemes for different water 723 economy branches 31.4 Aesthetic shaping of hydraulic schemes 726 31.5 River hydraulic schemes without pressure head 729 31.6 Low-head hydraulic schemes 730 31.7 Medium-head river hydraulic schemes 732 32 HYDRAULIC SCHEMES 735 32.1 High-head river hydraulic schemes on mountain rivers (Type I) 735 32.2 High-head hydraulic schemes on middle and low parts of rivers 747 32.3 Pumped-storage hydraulic scheme 753 33 RESERVOIRS 757 33.1 Introduction 757 33.2 Formation and safety of reservoirs 758 33.2.1 Stability of reservoir banks 758 33.2.2 Water-impermeability of the reservoir 762 33.2.3 Seismicity ofthe ground in the zone of the reservoir 765 33.2.4 Water absorption ofthe ground in the zone ofthe reservoir 766 33.2.5 Evaporation 767 33.2.6 Sediment accumulation 767 33.3 Resettlement of population and relocation of structures 770 33.4 Sports and recreational facilities 771 34 NEGATIVE EFFECTS OF HYDRAULIC SCHEMES AND 775 ENVIRONMENTAL PROTECTION 34.1 Types of negative effects on the environment 775 34.1.1 Changing the land into the area of the reservoir 776 34.1.2 Change of the flow downstream of the dam 777 34.1.3 Damming the migration paths of fish and wild animals 780 34.1.4 Change in the surrounding landscape and the microclimate 780 34.2 Social and ecological monitoring 782 34.3 Environmental protection - selection of a solution with minimum 783 negative effects on the environment 35 RESTORATION AND RECONSTRUCTION OF HYDRAULIC SCHEMES 787 35.1 Need for restoration and reconstruction 787 35.2 Restoration of dams and hydraulic schemes 788 35.3 Reconstruction of hydraulic schemes 795 References and Abbreviations 803 Subject Index Index of Dams