Hydraulic Gates and Valves in Free Surface Flow and Submerged Outlets

301 Pages·1995·33.016 MB·English

by  Jack Lewin

Hydraulic gates and valves
InFreeSurfaceFlowandSubmergedOutlets
JackLewin(Hon)DEng,CEng,FICE,FIMechE,
FCIWEM
Second Edition
PublishedbyThomasTelfordPublishing,ThomasTelfordLtd,1HeronQuay,London
E144JD.URL:http://www.thomastelford.com
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Firstpublished2001
AlsoavailablefromThomasTelfordBooks
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AcataloguerecordforthisbookisavailablefromtheBritishLibrary
ISBN:072772990X
(cid:223)JackLewinandThomasTelfordLimited,2001
Allrights,includingtranslation,reserved.ExceptaspermittedbytheCopyright,Designs
andPatentsAct1988,nopartofthispublicationmaybereproduced,storedinaretrieval
systemortransmittedinanyformorbyanymeans,electronic,mechanical,photocopying
or otherwise, without the prior written permission of the Publishing Director, Thomas
TelfordPublishing,ThomasTelfordLtd,1HeronQuay,LondonE144JD.
Thisbookispublishedontheunderstandingthattheauthorissolelyresponsibleforthe
statementsmadeandopinionsexpressedinitandthatitspublicationdoesnotnecessarily
imply that such statements and/or opinions are or reflect the views or opinions of the
publishers.Whileeveryefforthasbeenmadetoensurethatthestatementsmadeandthe
opinions expressed in this publication provide a safe and accurate guide, no liability or
responsibilitycanbeacceptedinthisrespectbytheauthororpublishers.
TypesetbyMHLTypesettingLtd,Coventry
PrintedandboundinGreatBritainbyMPGBooks,Bodmin,Cornwall
Contents
1. Introduction 1
2. Typesofgates 3
Gatesinfreesurfaceflow 4
Radialgates 4
Radialautomaticgates 9
Otherwateroperatedgates 15
Vertical-liftgates 17
Rolling-weirgates 22
Flapgates 23
Fusegates 33
Barrierandbarragegates 35
Drumandsectorgates 48
Bear-trapgates 50
Gatesinsubmergedoutlets 51
Intakegates 51
Controlandguardgates 53
Emergencyclosuregates,maintenancegatesandstoplogs 59
Summaryoftypesofgate 63
3. Valves 71
Sluicevalves 71
Butterflyvalves 71
Cavitationinvalves 75
Hollow-conevalvesandhoods 78
Hollow-jetvalves 84
Needlevalves 85
Pressure-reducingvalves 85
Spherevalves 87
Matchingterminaldischargevalvesandguardvalves 89
Summaryoftypesofvalve 90
Contents 4. Trashracks,screensanddebris 93
Trashracksandscreensinsubmergedintakes 93
Trashracksandscreensinculvertsandrivercourses 96
Screeninstrumentation 96
Screenraking 97
Debris 97
5. Structuralconsiderations 101
Designcriteria 101
Structuraldesignofradialgates 103
Structuraldesignofvertical-liftgates 107
Stiffeningmembersofskinplates 107
Compositeconstruction 109
6. Operatingmachinery 115
Electromechanicaldrives 116
Oilhydraulicoperationofgatesinfreesurfaceflow 121
Hoistspeed 126
7. Detaildesignaspects 127
Seals 127
Guideandloadrollers 137
Trunnionassembly 140
Trunnionbearingfailureandlubrication 142
Trunnionmountingforradialgates 144
Limitswitches 145
Ropes 147
Chains 148
8. Embeddedparts 151
9. Hydraulicconsiderationspertainingtogates 157
Flowunderandovergates 158
Hydraulicdownpullforces 166
Limitedponded-upwater 171
Three-dimensionalflowentryintosluiceways 171
Refluxdownstreamatapierandflowoscillation 171
Hysteresiseffectofgatedischargeduringhoisting/lowering 172
Hydraulicconsiderationspertainingtogatesinconduit 172
10. Gatevibration 185
Typesofgatevibration 185
Thevibratingsystem 186
Excitationfrequencies 188
Addedmass 191
iv
Preliminarycheckongatevibration 192 Contents
Vibrationduetosealleakage 194
Flowattachment,shiftingofthepointofattachmentand
turbulentflow 196
Hydraulicdownpullforcesandflowreattachmentat
thegatelip 199
Unstableflowthroughsmallopenings 200
Flowoverandundertheleavesofagate 201
Vibrationofoverflowgatesduetoinadequateventing 201
Vibrationduetoafreeshearlayer 201
Two-phaseflow 202
Slackingatecomponents 202
11. Controlsystemsandoperation 207
Controlobjectives 207
Operatingrulesandsystems 209
Telemetry 216
Factorsinthechoiceofautomaticgatecontrolsystems 217
Fall-backsystemandstandbyfacilities 218
Instrumentation 223
12. Hazardandreliabilityofhydraulicgatesandvalves 227
Eventsatspillwaygateinstallations 227
Incidentsandfailuresofbottomoutlets 232
Faultfrequencybygatetype 234
Riskassessmentofgatedhydraulicstructures 235
13. IceFormation 247
Ice 247
14. Earthquakeeffectsongates 251
Spillwaygateinstallations 252
Methodsofanalysis 254
Allowablestresses 255
Vertical-liftspillwaygateinstallations 255
Bottomoutlettunnelgates 256
Operatingmachineryunderearthquakeconditions 257
Systemsanalysis 257
Controlbuildings 261
Sampleeventtreeforaseismiceventonadam 261
15. Materialsandprotection 265
Materials 265
Steelcorrosionandpainting 266
Cathodicprotection 268
v
Contents 16. Modelstudies 271
Froudescalemodels 271
Two-phaseflowproblems 272
Two-andthree-dimensionalmodelstoFroudescale 272
Modelsforinvestigatingvibrationproblems 273
17. Environmentalconsiderations 277
Gatedrivercontrolstructures 277
Barriers 281
Barrages 281
18. Maintenanceandoperationofgateinstallations 285
Appendix:Calculationofhydrostaticloadonradialgates 289
Index 295
vi
Preface
The success of the first edition of this book has encouraged me to persist in
writingasecondedition.Somechaptersofthebookareintheiroriginalform,
withminimaladditions.Otherchaptershavebeensubstantiallyenlarged.New
chaptersdealwithhazardandreliability,earthquakeeffectsandenvironmental
impactofgateinstallations.ThesesubjectshavebecomemoreprominentsinceI
wrotethefirstedition,andIhaveattemptedtoprovideanintroductiontothe
particularproblemsatgatedstructures.
As in all fields of technology, the position is never static and a constant
stream of technical papers adds to our knowledge. It is impossible to deal
comprehensivelywithallthematerialwhichhasbecomeavailable;Itherefore
had to be selective about what to include. Even without absorbing new
material,itisdifficultforapractisingengineertocoverthefieldofhydraulic
gates and valves exhaustively as it incorporates aspects of many different
engineering disciplines. As a compensation, I like to think that my extensive
hands-on experience puts me in a better position to bridge the gap between
theory and practice, which is essential for the success of any engineering
endeavour.
I am indebted to all those who made valuable contributions to the book
based on their own specialist knowledge, particularly Mr Derek Wilden for
the first edition, and Drs Geoff Ballard and Mike Gardner for the second
edition. I owe much to Dr Paul Kolkman, formerly of Delft Hydraulics, for
hisgenerouspermissiontousematerialfromhisextensivepapers,fundamental
toanunderstandingofgatevibration.ThanksareduetoSueLambfortracing
thediagramsandtoMrMarkNobleforsupplyingmaterial.
IwouldalsoliketothankclientsforwhomIhavecarriedoutprojectsfor
permissiontouseinformationacquiredinthecourseofthiswork.
JackLewin,2001
vii
Acknowledgements
MythanksareduetomywifeBarbaraanddaughterJaqueline,whostruggledto
translatethemanuscriptintoareadableform.
Acknowledgementandthanksforpermissiontoreproducematerialfromthe
author’spapersaremadetoCIWEMforFigs2.8,2.16,2.56,2.57,2.58,2.60,
2.61,2.64,3.16,6.2,7.13,10.10and10.14.
Acknowledgement and thanks for permission to reproduce material are
similarlydueto:
BridonRopesLtdforTable7.2.
BritishHydromechanicsResearchGroup,CranfieldforFigs3.4^3.7.
ComputationalMechanicsCentre,SouthamptonforFigs2.11^2.15.
TheConsorzioVeneziaNuovaforFigs2.41^2.44.
DelftHydraulicsforFig.16.2.
TheElectricityCorporationofNewZealand,WaikatoHydroGroupandWater
PowerandDamConstructionforFigs11.8^11.12.
Goulburn^Murray Rural Water Authority and the Murray^Darling Basin
Commission,AustraliaforFigs5.5and7.17.
TheEnvironmentAgencyforthephotographinFig.2.37andFigs2.45^2.48,
5.4and7.4.
HydraulicResearch,WallingfordforFig.9.18.
HydroplusforFig.2.36.
TheInstitutionofCivilEngineersforFigs2.38^2.40.
TheInstitutionofMechanicalEngineersforFig.2.37.
IshikawajimaHarimaHeavyIndustriesCo.LtdforFigs2.49,2.59and2.63.
HansKˇnzGmbHforFig.4.3.
MannesmannRexrothforFigs6.7and6.8.
RenoldplcforFig.7.19(c).
ScottishandSouthernEnergyplcforFig.2.23.
SKF(U.K.)LtdforFigs7.14and7.16.
VoestAlpineGmbHforthephotographinFig.3.18.
J.M.VoithGmbHforFigs3.1^3.3,3.8,3.16and3.17.
1
Introduction
Thecontrolofrivers,canalsandreservoirsrequiresweirsorgatedstructures.
From considerations of reliability and maintenance, the fixed weir is the
preferredcontrolstructure.Similarly,thefixedcrestfreeoverflowspillwayis
the most advantageous arrangement for reservoirs. Wherever weirs or fixed
crest overflow spillways cannot be accommodated, or where the backwater
stages of a flood or variable river levels are unacceptable, a device which
providesamovablecrestorasubmergedvariabledischargeopeninghastobe
provided.Gatesandvalvesarethereforeanessentialandcriticalpartofmany
flood control schemes, of reservoir management and the control of water in
rivercourses.
Manytypesofgateareinsuccessfuloperation.However,onlyafewofthese
maybesuitableorcost-effectiveforaspecificsituation.Thechallengeistoselect
and design a gate of the most appropriate type and size which will meet the
hydraulic,operational,sitespecificandeconomicrequirements.
Gatesandvalvescontroltheflowofwater,sothehydraulicconditionsare
basictothesuccessoftheinstallation.Thiscomprisesnotonlytheflowunderor
overagatebutalsotheupstreamanddownstreamhydraulics.
Since gates are designed for extreme events, personal experience of their
performance under these conditions is by definition limited. Some gate
installationshavemetwithseriousdifficultiesinservice.Subsequentresearch
and published papers, sometimes presented at a specialist congress, are not
always disseminated widely enough to prevent repeated use of flawed design
features. This book attempts to combine available knowledge with practical
experienceofgatesandvalvesincivilengineeringstructures.
The first task is to provide a guide to selecting the right gate or valve.
Information on details of gate design is provided to help in an assessment of
thesuitabilityofagateforitstask,andthechapteronvalvesisintendedtoassist
in identifying the correct type of valve for its duty. Ancillary equipment
required in control structures, such as screens, stoplogs and handling
equipment,iscoveredinseparatechapters.
Lateron,spaceisgiventotheconsiderationofhazardandreliabilityofgates
andvalves.Thisispartofdamsafety,butitisalsoofparamountimportanceat
tidal defence barriers. Gated weirs and barrages control flood flow and their
failurecanresultininundationandseriousdamage.
1
Hydraulicgatesand Noteonunits
valves
The symbols used in the equations of the text, with few exceptions, have no
designatedunits.WhereverthisisthecaseconsistentSIunitscanbeused.
Noteonterminology
Theterm‘barrage’isusedinthebookforstructureswhichimpoundwater.
Theterm‘barrier’definesastructurewhichisbroughtintooperationtoprotect
ariveragainstanextremeevent,suchasstormsurge.
2