华北水利水电大学水利水电工程毕业设计外文翻译.docx

华北水利水电大学水利水电工程毕业设计外文翻译.docx

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华北水利水电大学水利水电工程毕业设计外文翻译

DESIGNCONSIDERATIONSOFAHIGHROCKFILLDAM

NAMNGUM2CFRD,LAOPDR

RuediStraubaar1,EvavanGunsteren2andStephenMoll3

1GeotechnicalandDamEngineeringExpert,PöyryEnergyLtd.（formerlyElectrowattEngineeringLtd.）Hardturmstrasse161,CH-8037Zurich,Switzerland

E-mail:

ruedi.straubhaar@

2ProjectEngineerandAssistantProjectManagerforNamNgum2,PöyryEnergyLtd.（formerlyElectrowattEngineeringLtd.）Hardturmstrasse161,CH-8037Zurich,Switzerland

E-mail:

eva.van-gunsteren@

3DamEngineer,PöyryEnergyLtd.（formerlyElectrowattEngineeringLtd.）Hardturmstrasse161,CH-8037Zurich,Switzerland

E-mail:

stephen.moll@

Abstract:

NamNgum2dam,alargeconcretefacerockfilldam（CFRD）of182mheight,isunderconstructionandimpoundingisscheduledtostartatbeginningofApril2010.Thedamissituatedinanarrowvalleyandfoundedonsedimentaryrockofvariablestrength.

Damdesignprinciplescomprisingdamzoning,faceslabdesignandinstrumentationareoutlined.Foundationtreatmentincludinggroutingandmeasuresbelowtheplintharepresented.Thepropertiesoftheavailablerockfillmaterialsandtheirinfluenceonthedamzoningarediscussed.

Emphasisisgiventotherockfillpropertiesandplacementprocedureswhichinfluencedambehaviourduringconstruction,impoundingandoperation.

Keywords:

CFRD,Rockfill,FaceSlab,Instrumentation

1NamNgum2HydropowerScheme

TheNamNgum2（NN2）hydropowerschemeislocatedontheNamNgumriverinLaoPDR,about90kmnorthofthecapitalcityofVientianeandsome35kmupstreamoftheexistingNamNgum1damandpowerhouse.Withaninstalledcapacityof615MW,theprojectwillproduceenergyfortheThaielectricitygrid.Asignificantcomponentoftheschemeisthe182mhighconcretefacerockfilldam,withavolumeof9.5Mm3andacrestlengthof500m.Thedamwillimpoundareservoirwithavolumeofapproximately4.2Mm3.

ConstructionoftheNN2Projectcommencedinlate2005andisscheduledforcompletioninthesecondhalfof2010.RockfillplacementinthedambodycommencedinJanuary2008,andwillbefinishedinearlyNovember2009.Faceslabconstruction,whichisdividedintoanupperandlowerstage,commencedinDecember2008andwillbecompletedbybeginningofApril2010,whenimpoundingwillbegin.Thereservoirwillfillduringonerainyseason,enablingcommissioningtotakeplaceduringthesecondhalfof2010.

2Considerationswithrespecttodamdeformations

Concretefacerockfilldamsareconsideredinherentlysafeforawiderangeofweakandstrongrockfill（Cooke1991）anddeformationoftherockfillisoftenassumednotbeingagoverningconcernprovidedthedamiswellengineeredandthedamfoundationisofadequatequality.Itisoftenassumedthatdamsettlementsareasimplefunctionofthedamheightandthattheyarenotlikelytoexceed1%ofthecompactedfillheightwithhorizontaldeformationslessthan50%ofthesettlements.Predictionsarealsooftenmadebasedonlaboratorytestsanddamdeformationanalyses.

2.1RockfilltestingperformedforNN2CFRD

FortheconstructionoftheNN2damquarriedrockofsedimentaryformationsareavailable.Thesourcematerial,consistingbasicallyofsandstoneandsiltstone,hasbeeninvestigatedbydrilling,quarrytrials,laboratorytestingandtrialembankmentconstruction.Theessentialtestsareindexpropertytests,compressivestrengthandbasicfrictionangletests.Testswerealsoperformedonsaturatedspecimen,whichnormallygivesmorerepresentativelowervalues.

Ofparticularinterestarealwayslargescaletriaxialandcompressibilitytests,whichhavebeencarriedoutforNN2bytheIWHR1inChina.

2.2DamanalysesandzoningofNN2CFRD

TestresultsfromtheIWHRaswellasresultsfromtheAIT2andsitelaboratorieswereusedasbasisfordamanalyses.Stabilityaswellas2Dand3DdeformationanalyseswerecarriedoutbytheIWHR.Basedontheresultsoftheanalysesandalsobasedonvisualobservationwhichindicatedaveryhighdesintegrationpotentialofthesiltstone,ithadtobeconcludedthatonlysandstoneissuitableasrockfillfortheconstructionofthehighembankment.Byusingonlysandstoneforrockfillitwasconcludedthatthedamdeformationwillbewithinacceptableandnormallimits.

Duringconstructionitwasobservedthatalsofinegrainedsandstone,porousorweatheredsandstoneofmoderatequalityisbeingobtainedfromquarryingwhichcannotalwayscompletelybeseparatedandwasted.Thereforethedamzoningwasadjustedtopermitalsoplacementoflower

qualityrockfillinthecentralpartofthedamembankment.TheadjusteddamzoningisshowninFigure2.

3Observeddeformationsonconstructeddams

Oftenitisassumedthatforstrongrockfillsthesettlementsaresmall,lessthanabout1%ofthefillheight.I