Geotechnical Engineering for Mine Waste Storage Facilities

641 Pages·2010·21.734 MB·English

by  Geoffrey E. Blight

Geotechnical Engineering for
MineWaste Storage Facilities
Geotechnical Engineering for
Mine Waste Storage Facilities
Geoffrey Blight
UniversityoftheWitwatersrand,Johannesburg,SouthAfrica
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LibraryofCongressCataloging-in-PublicationData
Blight,Geoffrey,1934-
Geotechnicalengineeringforminewastestoragefacilities/GeoffreyBlight.
p.cm.
Includesbibliographicalreferences.
ISBN978-0-415-46828-2(hardcover:alk.paper)1.Mineralindustries–Wastedisposal.2.Waste
disposalintheground.3.Environmentalgeotechnology.4.Engineeringgeology,5.Soilmechanics.I.Title.
TD428.M56B5852010
622.028’6–dc22
2009028816
Publishedby: CRCPress/Balkema
P.O.Box447,2300AKLeiden,TheNetherlands
e-mail:[email protected]
www.crcpress.com–www.taylorandfrancis.co.uk–www.balkema.nl
ISBN:978-0-415-46828-2(Hbk)
ISBN:978-0-203-85940-7(eBook)
Table of Contents
Author Biography XI
Acknowledgements XIII
List of Symbols XV
Chapter1: WasteEngineering,CharacteristicsofMineWastesand
TypesofWasteStorage 1
1.1 Thenatureandmagnitudeoftheminewastestorageactivity 1
1.2 Originsandquantitiesofminewaste 2
1.3 Theeffectsofclimate 5
1.4 Wastecharacteristics 7
1.5 Principlesofminewastemanagement 8
1.6 Typesofminewastestorage 12
1.7 Philosophyandarrangementofthisbook 19
Chapter2: SelectionofaSiteforStorageofMineWaste 25
2.1 Procedureforsiteselection 25
2.2 Preliminaryassessmentofrequiredsizeofsite 26
2.3 Possiblefatalflawsincandidatesites 27
2.4 Seekingandobtainingpublicacceptance 28
2.5 Preliminaryrankingofcandidatesites 30
2.6 Sitefeasibilitystudy 30
2.7 Riskanalysis 31
2.8 Environmentalimpactreport 36
2.9 Preliminarygeotechnicalcharacterizationofwaste 40
2.10 Preliminarysiteinvestigation 41
2.11 Finalsiteselection 47
2.12 Examplesofdisastrousselectionofsites 47
VI Table of Contents
Chapter3: GeotechnicalExplorationofSitesforDevelopmentof
MineWasteStorages 49
3.1 Soilengineeringsurvey 49
3.2 Soilengineeringdata 49
3.3 Detailedinformationfordesignofslopes&seepagecontrol 50
3.4 Profiledescription 51
3.5 Simpleinsitutestsandsoilsampling 57
3.6 Takingundisturbedsoilsamplesforlaboratorytesting 61
Chapter4: EnvironmentalandEngineeringCharacteristicsof
MineWaste,IncludingStressandStrainAnalysisand
LaboratoryShearTesting 67
4.1 Characteristicshavingenvironmentalimpact 67
4.2 Engineeringcharacteristics 68
4.3 Changesofwastecharacteristicswithtime,andotherconsiderations 70
4.4 Analysisofstressesandstrainsandtheprincipleofeffectivestress 73
4.5 Thebehaviourofminewastematerialssubjectedtoshear 86
4.6 Theprocessofconsolidationandporepressurere-distributionin
laboratorysheartests 121
4.7 Thestrengthandviscosityoftailingsatlargewatercontents 129
4.8 Theshearstrengthsofinterfaces 134
4.9 Theshearstrengthofwasterock 139
4.10 Strainsofteningof“dry’’coarseminewastes 141
4.11 Themechanicsofunsaturatedwastematerials 142
Chapter5: InSituShearStrengthTestingofTailingsandOther
WasteMaterialsanditsInterpretation 149
5.1 Theshearvanetest 150
5.2 Thepressuremetertest 160
5.3 Theconepenetrometertest 164
5.4 Estimationofpotentialforliquefactionfromconepenetration
tests 183
Chapter6: MeasuringtheCoefficientofPermeabilityintheLaboratory
andInSitu,SeepageFlowNets,DrainsandLinings,
Geosynthetics,GeomembranesandGCL’s 191
6.1 Measuringpermeability 191
6.2 Observeddifferencesbetweensmallscaleandlargescale
permeabilitymeasurements 192
6.3 Laboratorytestsforpermeability 194
6.4 Methodsformeasuringpermeabilityinsitu 197
6.5 Estimationofpermeabilityfromfieldtests 205
6.6 Large-scalepermeabilitytestsusingtestpads 208
6.7 Thepermeabilityoftailings 208
6.8 Seepageandflownets 212
6.9 Thedesignoffilterdrains 220
Table of Contents VII
6.10 Calculationofseepageratesthroughtailingsstorages 225
6.11 Theprocessesofconsolidationandporepressurere-distribution 229
6.12 Basalimperviouslinersandsurfacecoverlayers 235
6.13 Blockageoffilterdrainsandgeotextiles 242
6.14 Geosyntheticmaterials 245
Chapter7: TheMechanicsofCompaction 257
7.1 Thecompactionprocess 257
7.2 Usesofcompactioninminewasteengineering 259
7.3 Themechanismsofcompaction 260
7.4 Relationshipsbetweensaturatedpermeabilitytowaterflowand
watercontent 262
7.5 Laboratorycompaction 262
7.6 Precautionstobetakenwithlaboratorycompaction 263
7.7 Compactioninthefield 267
7.8 Designingacompactedclaylayerforpermeability 268
7.9 Seepagethroughfield-compactedlayers 270
7.10 Controlofcompactioninthefield 271
7.11 Specialconsiderationsforworkinclimateswithlargeratesof
evaporation 275
7.12 Additionalpointsforconsideration 276
Chapter8: MethodsforConstructingImpoundingDykesforStoring
HydraulicallyTransportedTailingsandOtherFine-Grained
Wastes 281
8.1 Depositionmethodsandsequences 281
8.2 Beachformationinhydraulicdepositionoffine-grainedwastes 284
8.3 Predictingbeachprofiles 290
8.4 Detailsofparticlesizesortingduringhydraulicdeposition 295
8.5 Effectsofparticlesizesortingonpermeability,watercontentand
strengthvariationdownabeach 299
8.6 Acomparisonoftailingsbeachesformedinairandinwater 302
8.7 Methodsfordepositingslurriesoftailingsandotherfine-grained
wastematerials 308
8.8 Operationalsystemsfortailingsstorages 322
8.9 Anexampleofbuildinganembankmentbyunderwaterdeposition 332
8.10 Poolcontrolanddecanting 335
Chapter9: WaterControlandFunctionalandSafetyMonitoringfor
HydraulicFillTailingsStoragesandDryDumps.Safety
Appraisal.SpecialConsiderationsforCarbonaceous
andRadioactiveWastes 339
9.1 Basisofawatercontrolsystem 339
9.2 Penstocksordecanttowersandspillways 341
9.3 Monitoringsystemsforwastestorages 358
9.4 Appraisalofsafetyforwastestorages 365
VIII Table of Contents
9.5 Specialconsiderationsforcarbonaceouswastes 368
9.6 Anoteoncharacteristicsofradioactivewastes 377
Chapter10: WaterBalancesforTailingsStorageFacilitiesand
DryWasteDumps 381
10.1 Waterbalancesingeneral 381
10.2 Requireddata 383
10.3 Componentsofthewaterbalanceforanoperationaltailingsstorage 383
10.4 Examplesofwaterbalancesforoperatinghydraulicfilltailings
storageimpoundments 385
10.5 Thepossibilitiesforsavingwater 392
10.6 Seepagefromthetailingsstorageintothefoundationstrataand
therecessionofthephreaticsurfacefollowingcessation
ofoperations 396
10.7 Drainageofinterstitialwaterasthephreaticsurfacerecedes 397
10.8 Thewaterbalancefora“dry’’dumporaclosedand
rehabilitatedtailingsstorage 399
10.9 Measuringpotentialinfiltrationandrunoff 400
10.10 Estimatingevaporationorevapotranspiration 405
10.11 Measuringevaporationbysolarenergybalance 409
10.12 Depthtowhichevaporationextends 423
10.13 Theeffectsofslopeangleandorientationonsolarradiation
receivedbyslopesofwastestorages 426
10.14 Waterbalancesfor“Infiltrate,Store,Evapotranspire’’(ISE)
coversandforimperviouscoverlayersonminewastestorages 430
10.15 Thewaterbalanceforadryashdump 437
10.16 Disposalofindustrialwasteliquidsbyevaporationand
capillarystorageinwaste 439
10.17 TheroleofsoilheatGinevaporationofwaterfromasoil 443
10.18 Furtherpointstoconsider 447
10.19 Principlesofthemeasuringweir 450
Chapter11: FailuresofMineWasteStorages 453
11.1 Failures:causes,consequences,characteristics 453
11.2 Failuresofhydraulicfilltailingsstoragescausedbyseismicevents 457
11.3 Flowfailurescausedbyovertopping 459
11.4 Failurecausedbyincreasingporepressure 473
11.5 Failurescausedbyexcessiverateofrise 475
11.6 Failurecausedbypoorcontrolofslurryrelativedensity 479
11.7 Post-failureprofilesofhydraulicfilltailingsstorages 482
11.8 Analysisofthemotionofflowfailures 487
11.9 Theeffectsoffailuregeometryoninsurancerates 489
11.10 Failuresofdumpsofcoarsewastes 490
11.11 Failurescausedbycollapseoftailingsstoragesinto
subterraneancavernsorundergroundworkings 501
11.12 Failuresofimperviousliningsinstalledonsteepslopes 503
Table of Contents IX
11.13 Methodsforanalysisofthestabilityofslopes 507
11.14 Furtherpointsregardingthefailureofslopes 514
Chapter12: SurfaceStabilityofTailingsStoragesSlopes–ErosionRates,
SlopeGeometryandEngineeredErosionProtection 519
12.1 Pastpracticeforslopeanglesoftailingsstorages 519
12.2 Acceptableerosionratesforslopes 520
12.3 Winderosioncomparedwithwatererosion 526
12.4 Acceptableslopegeometryfortailingsstorages 526
12.5 Protectionofslopesagainsterosionbygeotechnicalmeans 531
12.6 Specialconsiderationsapplyingtobadlyerodedabandonedor
neglectedtailingsstorages 546
12.7 Theeffectoferodedtailingsonthesurroundingsof
astorageofsulphidictailings 550
12.8 Windspeedprofiles,amplificationfactorsandwinderosion 552
12.9 Windspeedprofilesovernaturalandconstructedslopes 554
12.10 Windtunneltestsonmodelwastestorages 558
12.11 Erosionanddepositionbywindonfullsizewastestorages 561
12.12 Analysisofparticlemovementinthewind 566
12.13 Summaryofpointstobeconsidered 567
Chapter13: TheUseofMineWasteforBackfillingofMiningVoidsand
asaConstructionMaterial 571
13.1 Applicationsofbackfilling 571
13.2 Backfillingofshallowundergroundmineworkingstostabilize
thesurface 577
13.3 Thepropertiesofminewasteasastructuralundergroundsupport
innarrowstopes 583
13.4 Measurementsinsituofstressesandstrainsinfillsatgreatdepth 596
13.5 Supportingnarrowstopeswithsteel-reinforcedgranular
tailingsbackfill 598
13.6 Thebehaviourofsteelmesh-reinforcedsquarecolumnsof
cementedcyclonetailingsunderflow(groutpacks) 605
13.7 Theuseofgeotextilesfortemporaryretentionofbackfillin
narrowstopesduringhydraulicplacing 606
13.8 Theuseofmineandindustrialwastesinsurfaceconstruction 615
SubjectIndex 631
Author Biography
GeoffreyBlightcompletedhisBachelor’sandMaster’sdegreesinCivilEngineeringat
theUniversityoftheWitwatersrand,JohannesburgandhisPhDattheImperialCollege
ofScienceandTechnologyinLondon.Theearlyyearsofhiscareerwerespentatthe
South African National Building Research Institute, Pretoria, where he was engaged
inresearchondesign,operationandsafetyofminewastestoragefacilities,including
waste rock dumps and hydraulic fill tailings storage facilities. After the disastrous
failureofacoalwastedumpatAberfan,U.K.in1966,hewassentonacountry-wide
inspection tour of South African mines to make sure that no similarly threatening
stability situations existed locally. Eleven years later, after the disastrous failure of a
hydraulic fill tailings dam at Bafokeng, north of Johannesburg, he was asked by the
miningindustrytowriteacomprehensiveguidetothedesign,operationandclosureof
minewastestoragefacilities.Thisappearedin1979andhasbeenrevisedandupdated
severaltimessince.
Geoff Blight re-joined the Department of Civil Engineering at Witwatersrand Uni-
versityin1969andtheresultsofhiscontinuingresearchandconsultingworkonmine
waste have been widely published since. The present book has been developed from
theupdatedminingindustryguideaswellasaseriesofpostgraduatecoursesinmine
wastemanagementthathavebeenpresentedformanyyears.
Inadditiontonumeroustechnicalpaperspublishedinrefereedjournalsandconfer-
enceproceedings,heistheeditorandco-authorofthebook“MechanicsofResidual
Soil’’(Balkema,1997)andauthorof“AssessingLoadsonSilosandOtherBulkstorage
Structures’’(TaylorandFrancis2006).
Acknowledgements
I was first introduced to the fascinating subject of geotechnical engineering by Jere
Jennings when I was a final year student at the University of the Witwatersrand in
1955. As mining was, and continues to be a major industry involving geotechnical
engineeringinSouthAfrica,manyofJere’steachingexamplesinvolvedthegeotechnics
ofminewaste,asubjectthathasenthralledmeeversince.Jerealsointroducedmeto
thesubjectofunsaturatedsoilmechanics,which,livinginthewater-deficientclimate
of South Africa, was almost inevitable and very necessary. When, a few years later,
I studied at the Imperial College in London, my PhD supervisor was Alan Bishop,
anotherofthepioneersinthefieldsofminewasteandunsaturatedsoils.Itwasthese
twoengineerswhosecontributionstomycareerInowrememberwithgratitude.
I have also been assisted over the past fifty or so years by a number of fellow
geotechnicalengineers,manyofwhomstartedoutasmystudentsandbecamefriends
andprofessionalcolleaguesandwithwhomIamgratefultohavebeenassociated.In
particular, I acknowledge the friendship and assistance of Oskar Steffen, Eric Hall,
John Nelson, Dick Dison, Neville Graham, Ken Lyell, Brian Wrench, Mike Smith,
DerekAvalle,DaveBentel,GordonMcPhail,JeremyBoswell,RodBall,AndyFourie,
Sam Spearing, Adriaan Meintjies, Jenny Blight and Krassimir Roussev, all of whom
havecontributeddirectlyorindirectlytothisbook.
It has also been my good fortune to have enjoyed the support of four outstanding
technicianswhileattheUniversityoftheWitwatersrand. BobvanderMerwe, Frans
Wiid,EdBraddockandNormanAlexanderalwaysmademyschemeshappenbothin
thelaboratoryandinthefield.Inparticular,mostoftheexperimentalresultsincluded
inthebookaretheworkofNormanAlexander.
Cathy Snow produced the figures and plates and patiently endured the countless
changesandadditionsthatweremade.
I particularly acknowledge and am extremely grateful for the unwavering support
ofmywifeRhonawhopatientlyproducedthemanuscriptofthebook.
Unlessotherwiseacknowledged,allphotographsweretakenbytheauthor.
GeoffBlight
Johannesburg
July2009