Concrete in Hydro-power structures

8/13/2019 Concrete in Hydro-power structures

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HYDROPOWER DEVELOPMENT

VOLUME NO 11

CONCRETE IN

HYDROPOWER STRUCTURES

by

Erland Kleivan, Gunnar Kummeneje and Alf J. Lyngra

1994

NORWEGIAN INSTITUTE OF TECHNOLOGY

DIVISION OF HYDRAULIC ENGINEERING


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CONTENTS

Abbreviations, Acronyms and Definitions ..................................................8

1 INTRODUCTION ......................................................................................91.1 Brief review of the use of concrete in the hydropower industry ......... 91.2 Highlights in recent development of concrete technology .................. 101.3 Design for durability requires knowledge ............................................. 12

2 THE CONSTITUENTS OF CONCRETE .................................................132.1 Cements and pozzolana .......................................................................... 132.2 Aggregates .............................................................................................. 182.3 Water ....................................................................................................... 192.4 Admixtures .............................................................................................. 19

2.4.1 Definitions ..................................................................................... 192.4.2 Plasticizers/water reducers ........................................................... 20

2.4.3 Air-entraining Agents ................................................................... 212.4.4 Accelerators .................................................................................. 212.4.5 Retarders ....................................................................................... 222.4.6 Admixtures for underwater concreting ....................................... 22

3 FRESH CONCRETE CRITERIA FOR MIX DESIGN .......................233.1 Water/cement ratio ................................................................................. 233.2 Type of structure ..................................................................................... 233.3 Workability/consistency ......................................................................... 253.4 Ambient temperature .............................................................................. 253.5 Means and length of transport ............................................................... 26

4 CURING ..........................................................................................................274.1 Need for proper curing ........................................................................... 274.2 Methods and means of curing ................................................................ 284.3 Plastic shrinkage ..................................................................................... 294.4 Prediction of temperature and strength development ........................... 29

5 THE HARDENED CONCRETE REQUIREMENTS AND PROPERTIES ................................................315.1 On the criteria for specifying properties ............................................... 315.2 Durability. Sources of deterioration and preventive measures 31

5.2.1 Classification of environment .................................................... 31

5.2.2 Preventing corrosion of reinforcement ...................................... 33

5.2.3 Resistance to erosion/abrasion and cavitation ........................... 34


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5.2.4 Resistance to chemical attack ................................................. 34

5.2.5 Resistance to freezing and thawing ......................................... 37

5.3 Watertightness .................................................................................. 38

5.4 Structural strength ............................................................................ 39

6 REINFORCEMENT ................................................................................ 43

6.1 Notes on bar reinforcement .............................................................. 436.2 Fibres ................................................................................................ 44

6.3 Galvanized reinforcement ................................................................. 44

7 CONCRETE IN DAMS ........................................................................... 45

7.1 General requirements to concrete properties .................................... 45

7.2 Concrete dams .................................................................................. 46

7.2.1 General comments ................................................................... 46

7.2.2 Small gravity structures .......................................................... 46

7.2.3 Large gravity dams .................................................................. 47

7.2.4 Arch dams ............................................................................... 48

7.2.5 Slab and buttress dams ............................................................ 49

7.2.6 Roller-compacted concrete dams ............................................ 51

7.3 Concrete in embankment dams ......................................................... 52

7.3.1 General .................................................................................... 52

7.3.2 Central concrete membranes ................................................... 52

7.3.3 Upstream concrete membranes ............................................... 52

7.3.4 Retaining walls ........................................................................ 53

7.3.5 Other use of concrete in embankments ................................... 53

8 CONCRETE IN WATERWAYS ............................................................ 57

8.1 Tunnels ............................................................................................. 578.1.1 General Comments .................................................................. 57

8.1.2 In situ concrete lining .............................................................. 57

8.1.3 Shotcrete ................................................................................. 60

8.1.4 Pavements ............................................................................... 62

8.1.5 Grouting .................................................................................. 62

8.1.6 High pressure plugs ................................................................. 63

8.1.7 Low pressure plugs ................................................................. 69

8.2 Penstocks and other pressure conduits ............................................. 69

8.2.1 General .................................................................................... 69

8.2.2 Surface conduits ...................................................................... 708.2.3 Underground conduits ............................................................. 71

8.3 Surge chambers ............................................................................... 73

8.4 Weirs ................................................................................................. 73

8.5 Gates ................................................................................................ 74

8.6 Intakes ............................................................................................. 75

8.7 Canals .............................................................................................. 76

8.8 Culverts ........................................................................................... 77

8.9 Fish ladders ..................................................................................... 77


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9 CONCRETE IN POWERHOUSES ........................................................799.1 Typical underground powerhouses ................................................... 79

9.1.1 General .................................................................................... 799.1.2 The cavern ............................................................................... 799.1.3 Access and auxiliary tunnels ................................................... 82

9.2 Typical above ground powerhouses .................................................. 849.2.1 General .................................................................................... 849.2.2 In situ concrete components .................................................... 85

9.3 Prefabricated elements ...................................................................... 879.3.1 General .................................................................................... 879.3.2 Roof elements .......................................................................... 87

9.3.3 Floor elements ......................................................................... 889.3.4 Trash rack beams ..................................................................... 889.3.5 Other products ......................................................................... 899.3.6 Advantages/disadvantages with prefabrication ....................... 89

10 QUALITY ASSURANCE .....................................................................9110.1 General comments .......................................................................... 91

10.2 Concrete QA for the consultant ...................................................... 9110.3 Concrete QA for the contractor ....................................................... 93

11 DAMAGE AND REPAIR .....................................................................9511.1 General ............................................................................................ 95

11.2 Diagnosis ......................................................................................... 9611.3 Repair methods ............................................................................... 97

REFERENCES ............................................................................................101

CASE HISTORIES .....................................................................................105

Case 1: Planning and implementing concrete works for a largegravity dam. Forrevatn Dam .............................................................. 107

Case 2: Concrete composition and cooling arrangement for anarch dam. Virdnejavri Dam ............................................................... 112

Case 3: Design and construction of a high pressure penstock plug. Nyset-Steggje Power Plant ........................................................................... 114

Case 4: Design and construction of a high pressure gated plug.

Mel Power Plant ................................................................................ 116

Case 5: Design and construction of a high pressure barrier plug.Nedre Vinstra Power Plant ................................................................ 119

Case 6: Concreting of steel penstock in long shaft.Aurland I Power Plant. Unit 3 (1989) ............................................... 122

Case 7: Concrete work for large-scale spiral case roof.Solbergfoss II Power Plant (1983) ................................................... 124

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Concrete in Hydro-power structures