Hydraulic Structures

382 Pages·2020·9.737 MB·English

by  C S James

C S James
Hydraulic Structures
Hydraulic Structures
C S James
Hydraulic Structures
123
CSJames
Schoolof Civil andEnvironmental
Engineering
University of the Witwatersrand
Johannesburg, SouthAfrica
ISBN978-3-030-34085-8 ISBN978-3-030-34086-5 (eBook)
https://doi.org/10.1007/978-3-030-34086-5
©SpringerNatureSwitzerlandAG2020
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Preface
This textbook is intended to provide for the needs of senior undergraduate and
postgraduate students in civil engineering programmes and graduate engineers in
civil engineering practice. It aims to provide a solid grounding in the theory
underlying the design and analysis of hydraulic structures, including underflow
gates,transitions,spillways,culverts,energydissipators,flowmeasuringstructures
and river intakes, as well as the prediction and prevention of scour.
Well-established theory and procedures are presented, as well as recent develop-
mentsgleanedfromtheresearchliteraturewithadesign-orientedperspective.Asa
learning resource, the book is not intended to provide complete design details, but
rather to develop understanding and competence in applying basic theoretical
concepts; the reader is directed to many freely available design guides for more
detailed treatment. There is, however, sufficient detail for preliminary design of
manystructuresandcompletedesignofsomestandardstructuressuchasmeasuring
weirs and flumes and stilling basins. Worked examples are presented in each
chapter and exercise problems are provided.
Thecontentofthebookisbasedonapostgraduatecourseinhydraulicstructures
presentedattheUniversityoftheWitwatersrand,Johannesburgovermanyyears.At
this level, mastery of basic hydraulic theory is assumed. For revision, the intro-
ductory chapter provides an overview of the basic concepts relevant to the subse-
quentcontent,particularlycoveringsteadyrapidlyandgraduallyvariedflowinopen
channels, and flow resistance. At postgraduate level, students and practitioners
should be aware of the incompleteness of current knowledge, and be adept at
keeping abreast of new developments. Knowledge of some topics presented in the
book is clearly not yet definitive, but their inclusion exemplifies the evolving state
oftheartandthereferencescitedprovidefirstrecourseforpursuingadvancements.
I am indebted to the authors of the many books and articles from which I have
gainedtheknowledgethatispresentedinthiswork.Ihaveacknowledgedalldirect
sources as far as possible, but there is much accumulated influence that is implicit
v
vi Preface
anddifficulttosourceandattribute.IamespeciallyindebtedtoDr.HeinzWeissfor
inspiring my interest in open channel hydraulics as an undergraduate student so
many years ago, and to my many students since who have challenged my under-
standing and explanations.
Johannesburg, South Africa C S James
Contents
1 Basic Hydraulic Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Flow Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 The Conservation Laws in Hydraulics . . . . . . . . . . . . . . . . . . . . . 7
1.3.1 Conservation of Mass—The Continuity Equation . . . . . . . 7
1.3.2 Conservation of Energy . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.3 Conservation of Momentum. . . . . . . . . . . . . . . . . . . . . . . 12
1.4 Steady Uniform Flow and Flow Resistance . . . . . . . . . . . . . . . . . 14
1.4.1 The General Resistance Equation . . . . . . . . . . . . . . . . . . . 15
1.4.2 The Chézy Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.4.3 The Darcy–Weisbach Equation. . . . . . . . . . . . . . . . . . . . . 18
1.4.4 The Manning Equation . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.5 Steady Rapidly Varied Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.5.1 Application of Energy and Momentum Conservation. . . . . 28
1.5.2 The Control Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.6 Steady Gradually Varied Flow . . . . . . . . . . . . . . . . . . . . . . . . . . 49
1.6.1 The Gradually Varied Flow Equation . . . . . . . . . . . . . . . . 50
1.6.2 Classification of Gradually Varied Profiles . . . . . . . . . . . . 51
1.6.3 Gradually Varied Flow Computation. . . . . . . . . . . . . . . . . 52
Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
2 Underflow Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.2 Unsubmerged Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.3 Submerged Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
2.4 Hysteretic Behaviour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
vii
viii Contents
3 Open Channel Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.2 Subcritical Flow Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.3 Supercritical Flow Transitions. . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.3.1 Straight Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
3.3.2 Curvilinear Transitions. . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3.3.3 Suppression of Standing Wave Propagation. . . . . . . . . . . . 94
3.4 Dual Stable States and Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . 97
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4 Spillways. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
4.1 Introduction to Conveyance Structures. . . . . . . . . . . . . . . . . . . . . 105
4.2 Spillway Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
4.2.1 The Overflow Spillway . . . . . . . . . . . . . . . . . . . . . . . . . . 108
4.2.2 Labyrinth and Piano Key Weirs . . . . . . . . . . . . . . . . . . . . 117
4.2.3 The Side-Channel Spillway . . . . . . . . . . . . . . . . . . . . . . . 119
4.2.4 The Side Weir. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
4.2.5 Shaft (Morning Glory) Spillways . . . . . . . . . . . . . . . . . . . 130
4.2.6 Siphon Spillways. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
4.2.7 Chutes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
4.2.8 Stepped Chutes and Spillways . . . . . . . . . . . . . . . . . . . . . 146
4.3 Cavitation and Aeration on Spillways and Chutes. . . . . . . . . . . . . 150
4.3.1 Cavitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
4.3.2 Aeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
5 Culverts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
5.2 Inlet Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
5.3 Outlet Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
6 Energy Dissipation Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
6.2 The Hydraulic Jump. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
6.2.1 Hydraulic Jump Characteristics. . . . . . . . . . . . . . . . . . . . . 184
6.2.2 Controlled Hydraulic Jumps. . . . . . . . . . . . . . . . . . . . . . . 195
6.3 Standard Stilling Basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
6.4 Other Energy Dissipators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
6.4.1 Bucket-Type Dissipators . . . . . . . . . . . . . . . . . . . . . . . . . 225
6.4.2 Impact-Type Dissipators. . . . . . . . . . . . . . . . . . . . . . . . . . 228
6.4.3 Baffled Spillways. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
Contents ix
6.4.4 Stepped Chutes and Spillways . . . . . . . . . . . . . . . . . . . . . 231
6.4.5 Spillway Splitters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
7 Flow-Measuring Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
7.2 Weirs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
7.2.1 Sharp-Crested Weirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
7.2.2 Broad-Crested Weirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
7.2.3 Advantages and Disadvantages of Weirs for Flow
Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
7.3 Flumes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
7.3.1 Throated (Venturi) Flume. . . . . . . . . . . . . . . . . . . . . . . . . 257
7.3.2 The Parshall Flume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
7.3.3 The Cutthroat Flume . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
7.4 Long-Throated Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
7.5 Errors and Measuring Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
8 Intake Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
8.1.1 Reservoir Intakes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
8.1.2 River Intakes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
8.2 River Intake Design for Sediment Control . . . . . . . . . . . . . . . . . . 285
8.2.1 Vertical Sediment Distribution . . . . . . . . . . . . . . . . . . . . . 286
8.2.2 Bed Load Movement Around Bends. . . . . . . . . . . . . . . . . 290
8.2.3 Sediment Exclusion Structures . . . . . . . . . . . . . . . . . . . . . 292
8.3 Pump Sumps and Intakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
8.3.1 Desirable Flow Conditions. . . . . . . . . . . . . . . . . . . . . . . . 307
8.3.2 Intake and Sump Design . . . . . . . . . . . . . . . . . . . . . . . . . 309
8.3.3 Model Testing for Intakes . . . . . . . . . . . . . . . . . . . . . . . . 315
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
9 Scour and Scour Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
9.2 Theoretical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
9.3 Empirical Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
9.4 Design Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
9.4.1 Critical Shear Stress Design . . . . . . . . . . . . . . . . . . . . . . . 327
9.4.2 Permissible Velocity Design. . . . . . . . . . . . . . . . . . . . . . . 336
9.4.3 Protection of Underlying Material. . . . . . . . . . . . . . . . . . . 339
x Contents
9.5 Scour Around Bridge Piers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341
9.5.1 Scour Depth Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . 342
9.5.2 Bridge Scour Countermeasures. . . . . . . . . . . . . . . . . . . . . 351
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
Postscript. .... .... .... .... ..... .... .... .... .... .... ..... .... 365
Index .... .... .... .... .... ..... .... .... .... .... .... ..... .... 367