Most dam accidents with hydroelectric plants are due to under-dimensioning of the maximum floods of spillway design, causing extravasation and dam breaks (this occurs in 23% of the accidents). This work highlights the relationship between spillway design and potential dam failure and other important aspects of these structures and presents the methodology of design based on the international experience on the subject.
The book covers river basin studies and floods (the geology, geomorphology, hydrology, hydraulics, and layouts of the works). Further, spillway function, capacity and design flood, layouts, or arrangements, of hydroelectric works and types of spillways are treated in the book. Finally, the book discusses examples of dams that broke due to insufficient spillway capacity.
The book is intended for engineers and the companies that design dams and power plants around the world, as well as students in dam and hydraulic engineering. In short, people interested in producing electricity that is clean and potentially cheaper than other sources.
1 Introduction
1.1 Initial considerations
1.2 Phases of studies of the basin. The cases of Banqiao (China), Mascarenhas de Moraes and Itá (Brazil)
1.3 Spillway and design flood
The case of the Mascarenhas de Moraes HPP
1.4 Layout and choice of spillway
1.5 Two notable cases: Theodore Roosevelt (USA) and Orós (Brazil)
1.6 Ruptures of dams due to insufficient discharge capacity of the spillway
1.7 Risks of dam ruptures – submersion waves
1.8 Case of rupture by earthquake
1.9 Operation and maintenance
2 Types of spillways
2.1 Classification of the spillways
2.2 Ogee spillway
2.3 Side spillway
2.4 Morning glory spillway
2.5 Tunnel spillway
2.6 Chute spillway
Barra Grande HPP, Pelotas river (Rio Grande do Sul/Santa
Catarina States, Brazil)
Campos Novos HPP, Canoas river (Santa Catarina State, Brazil)
Corumbá HPP, Corumbá river (GO, Brazil)
Serra da Mesa HPP, Tocantins river (GO, Brazil)
2.7 Culvert spillway (bottom outlet)
2.8 Orifice spillway
2.9 Labyrinth spillway
2.10 Siphon spillway
2.11 Stepped spillway
2.12 Horizontal apron spillway (spillway without ogee)
3 Spillway design
3.1 Initial considerations
3.2 Ogee shape
3.3 Hydraulic design
3.4 Practical rules for defining the type of spillway
3.5 Hydraulic design of the ogee spillway – example of Tucuruí
3.6 Hydraulic design of other types of spillway – notes
4 Hydrodynamics pressures
4.1 Initial considerations
4.2 Average pressures
4.3 Instant pressures – Shin-Nariwa (Japan)
Forces acting in the chute/powerhouse roof slab
Powerhouse roof slab oscillations
Variation of Cp
4.4 Instant pressures – Karakaya
4.5 Instant pressures – Tucuruí (Brazil)
5 Energy dissipation
5.1 Classification of the dissipators
5.2 Ski jump dissipators
5.3 Hydraulic jump dissipators
5.4 Cases
6 Pressure forces downstream of dissipators
6.1 Hydrodynamics pressures downstream of ski jumps
6.2 Example: pressure bulb in the pre-excavation downstream of the Tucurui spillway
6.3 Example: pressure bulb in the pre-excavation downstream of the Jaguara spillway
6.4 Hydrodynamics pressures downstream of stilling basins
6.5 Hydrodynamics pressures downstream Canoas I HPP
spillway stilling basin
7 Evaluation of the scour
7.1 Scour holes in hydraulic models
7.2 Estimate of scour holes depths; Veronese equation
7.3 Yuditskii iterative method
Conditions for pulling off the block from the rocky bed of the river
7.4 Comprehensive scour model
8 Cavitation
8.1 Conceptualization and characteristic parameters
8.2 Cavitation caused by irregularities
8.3 Protective measures – surface finish specifications
8.4 Cavitation cases
8.5 Cavitation cases in culvert (bottom outlets)
8.6 Aeration
9 Gates and valves
9.1 Types and components of the gates
9.2 Classification of the gates
9.3 Selecting the type of gate
9.4 Limits of use
9.5 Flow coefficients of outletworks
9.6 Discharge coefficients of spillways radial gates
9.7 Risks of the gates
9.8 Rupture of radial gate of the Folsom dam spillway
9.9 Valves
10 Hydraulic models
10.1 Summary of theory
10.2 Definition of the model and laws governing the models
10.3 Types of models
10.4 Materials and methods of construction. Equipment
10.5 Hydraulic models of the Tucuruí spillway
Approach of the flow to spillway – abutments 343
11 Specific constructive aspects of hydraulic surfaces
11.1 Tucuruí spillway
11.2 Jaguara spillway
11.3 Mascarenhas de Moraes spillway
11.4 Heart Butte spillway
11.5 El Guapo spillway
11.6 Belo Monte spillway
11.7 Colíder spillway
11.8 São Manoel spillway
11.9 Santo Antônio spillway
11.10 Mauá spillway
References 361
Appendix 1 Spillways deterioration and rehabilitation
Operation and maintenance
Australia (Eildon dam)
South Korea (Imha dam)
India (Hirakud dam; Narayanapur dam)
México (La Villita dam; Malpaso dam; Peñitas dam; Infernillo dam)
Appendix 2 Overflow dams
Rockfill overflow dams
Overflow dams with the downstream face lined
Overflow dams with stepped spillway
Biography
Geraldo Magela Pereira (Civil Engineering, University of Brasilia, 1974; MSc Civil Defense, Fluminense Federal University, Niteroi, 2016) is hydraulic & geotechnical engineer, and served as coordinator of several hydropower projects. Covering hydropower plant lay-outs, construction planning, project management in all stages of studies and projects, inventory and feasibility studies, basic and executive designs, including hydraulic studies on models. In the last twenty years he worked in commercial areas developing offers for EPC (Engineering, Procurement and Construction) of power plants.
He is author of three books in Portuguese: Power Plant Design – step by step, 2015; Design of Spillways – step by step, 2017; Accidents and Dam Breaks, 2018.
