Safety Check of Existing Dam Against Altered Seismic Hazard Conditions MARY JAMES

7/27/2019 Safety Check of Existing Dam Against Altered Seismic Hazard Conditions MARY JAMES

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INTERNATIONALJOURNALOFCIVILANDSTRUCTURALENGINEERING

Volume3,No1,2012

Copyrightbytheauthors-LicenseeIPA-UnderCreativeCommonslicense3.0

ResearcharticleISSN09764399

ReceivedonJune,2012PublishedonAugust2012239

SafetycheckofexistingdamagainstalteredseismichazardconditionsGaurvaVerma

1,VermaM.K

2,TripathiR.K

3

1-M.Tech(WaterResources),CivilEngineeringDept.,NationalInstituteofTechnology,

Raipur,Chhattisgarh,India2-Professor,CivilEngineeringDept.,NationalInstituteofTechnology,Raipur,Chhattisgarh,

India

3-AssociateProfessor,NationalInstituteofTechnology,Raipur,Chhattisgarh,India

[email protected]

doi:10.6088/ijcser.201203013023

ABSTRACT

The paperpresentsseismichazardanalysisofGangreldamsituatedinChhattisgarh,India

using CADAM. The static and seismic safety of existing concrete gravity dams is acontinuousconcernowingtothedynamicseismicactivitiesduetothetectonicmovementof

theearthplates.Thesetectonicmovementsresultsinearthquakesandmayaltertheimportant

seismicparameterslikePeakGroundAcceleration(PGA).Earthquakeactionsaretakeninto

account pseudo statically through inertia force characterized by a seismic coefficient.The

designcheckofexistingdammustbeperformedtoassesswhetherseismicupgradingofa

particularplaceis necessary fromseismicsafety pointofview.According toNRC (1985)

Damsafetymusttakeprecedenceoverallotherconsiderations.CADAMsoftwarehasbeen

used for design check. Seismic analysis is done using the pseudo static method.Gangrel

Dam,amajordaminCGstatewasconstructedintheyear1979.RevisedSeismicparameter,

PGAforthissitehadbeenreportedintheyear2006-07.Withreferencetoalteredvalueof

PGA, seismichazardanalysisforGangreldamhasbeenperformedandpresented throughthis paper. The Dam stability is checked for altered value of PGA for various loading

conditionsanditwasfoundtobewithinsafelimitspresently.

Keywords:DeterministicSeismichazardAnalysis,MCE(MaximumCredibleEarthquake),

OBE(OperatingBasisEarthquake),PGA(PeakGroundAcceleration),PseudostaticSeismic

analysis,SeismicHazard.

1.Introduction

Earthquakes are vibrations caused by movement of base rocks along fault surfaces.Most

earthquakesoccurwhentheenergystoredbyelasticdeformationintherocksonbothsidesofafaultisenoughtorupturetherocksortoovercomethefrictiononanexistingfaultplane.

The deformation isunderstoodasbeing causedbyinternal forces such asofconvectional,

gravitational andmagneticorigins.The energy of the earthquake, generated at the fault is

radiatedoutwardsbymeansofelasticwaves.Asthesewavestravelthroughandalongthe

crustoftheearththeyshaketheearthinalldirectionswithvaryingdegreeofintensityand

thepatternofoscillation changesbyrefraction, reflectionand superpositionofonetypeof

waveonothers.Generallythemagnitudeofthesewavesdecreasewithdistance.Thesizeof

an earthquake depends on the amount of energy released. This can be measured by

earthquakemagnitude.Theamountofenergyreleasedinturncanberelatedtothesizeofthe

geologicoffset,faultparametersandtotheconsequencesoftheseismichazardonpeopleand

theirenvironment.Thesefaultmovements,groundshakingandlandslidecaninduceseismic


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Safetycheckofexistingdamagainstalteredseismichazardconditions

GaurvaVerma,VermaM.K,TripathiR.K

InternationalJournalofCivilandStructuralEngineering240Volume3Issue12012

hazard on dams. These in turn result in deformation, liquefaction, slope instability and

overtoppingofthewaterofthedam.

Earthquakespresentathreattopeopleandthefacilitiestheydesignandbuild.Seismichazard

Analysis(SHA)istheevaluationofpotentiallydamagingearthquakerelatedphenomenonto

whichafacilitymaybesubjectedduringitsusefullifetime.SHAisdoneforsomepractical

purpose, typically seismic resistant design or retrofitting. SHA involves the quantitativeestimationofgroundshakinghazardsataparticularsite.Kramer(1996)consideredthatthe

seismichazardsmaybeanalyzeddeterministicallywhenaparticularearthquakescenario is

assumed,orprobabilistically,inwhichuncertaintiesinearthquakemagnitude,locationsand

timeofoccurrencesareexplicitlyconsidered.PGAandResponseSpectrumarethemain

Stronggroundmotionparametersalteredduringanearthquakeevent.

Seismicsafetyassessmentconsistsbasicallyof

1. Seismic Hazard assessment, which includes the seismotectonic features (i.e. faultmovements),andthegroundshaking(accelerationtimehistories)fordifferenttypeof

designearthquakes;2. (Seismic response analysis, which combines the model of the dam-reservoir

foundationsystem,thematerialpropertiesandthemethodofanalysis;

3. Performanceassessmentwhichincludespossibledamageassessment.

Similar analysis was performed forHoover Dam using two different approaches.Chopra

A.K. and Hanchen T. (1996)applied a 3-D linearelastic analyses using EACD3D96

incorporating foundation structure interaction with mass in the foundation, impedance

contrast between the dam and the foundation. Payne (1998) and Chopra (2001) studied.

hydrodynamic interaction using compressible fluid . Koltuniuk (1997) used a second

approach of a non-linear three dimensional dynamic finite element analysis incorporating

concrete cracking and contraction joint interaction using smeared crack techniques.

Mills(1997) studied the kinematic stability analysis of the top of the dam. Gupta, (2002)

stated that the seismichazard analysis isconcernedwithgettinganestimateof the strong

motionparametersatasiteforthepurposeofearthquakeresistantdesignorseismicsafety

Assessment. CADAM is based on the gravity method (rigid body equilibrium and beam

theory).Itperformsstabilityanalysesforhydrostaticloadsandseismicloads.

2.Studyarea

Gangrel is a multipurpose concrete gravity dam constructed across river Mahanadi at

204236N latitude and 813259E longitude in Chhattisgarh, India. The dam wascompletedin1979,hasacrestlengthof455m,acrestthicknessof7mandamaximumbase

widthof14m.AccordingtoGlobalSeismicHazardAssessmentProgram(GSHAP)data,the

stateofChhattisgarhfallsinregionoflowseismichazardwiththeexceptionbeingmoderate

hazard in areas alongMaharashtra and AP state borders. The dam site is considered in

seismiczoneIIasperI.S.1893(part-I):2002.

2.1.Geology

The dam is a part of the Mahanadi Project. Mahanadi project area is locatedwithin the

Chhattisgarh sedimentary basin. This is formed by an ancient sequence of sand stones,

carbonate, rocks(limestones anddolomites) and shaleswhichare preservedwith adownfaultedblockonthecrystallinebasement.Stablelandsurfacehavedevelopedathicklaterite


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cover.Sandyalluviumoccursalongsomereachesofthemajorrivercoursesandthereisa

relativelyextensiveareaofcoarsealluviumintheSouthernpartofthecommand.

Atthedamsite,Chandrapursandstone(quartzitesandstone)areexposedintheleftflank

and are available in depth of about 7 to 10 metres for about half the river width. In the

remainingwidththerockistotallyscouredoutandisnotavailableevenatagreatdepth.Clay

andbouldersareavailablebelowsandinthisportionoftheriverandontherightflank.

2.2.Methodology

The pseudo-static slope stability analysis is done with the conventional limit equilibrium

methodby usingthe design groundmotion as aninput.The analysis isperformed for the

upstream and down stream slopes of the dam by varying the possible critical cases. The

evaluationofthestructuralstabilityofthedamagainstsliding,overturningandupliftingis

performed considering two distinct analyses, a stress analysis to determine eventualcrack

length and compressive stresses, a stability analysis to determine the (i) safety margins

againstslidingalongthejointconsidered,and(ii)thepositionoftheresultantofallforces

actingonthejoint.

The use of the gravity method requires several simplifying assumptions regarding the

structuralbehaviorofthedamandtheapplicationoftheloads

1. Thedambodyisdividedintoliftjointsofhomogeneouspropertiesalongtheirlength,themassconcreteandliftjointsareuniformlyelastic,

2. Allappliedloadsaretransferredtothefoundationbythecantileveractionofthedamwithoutinteractionswithadjacentmonoliths,

3. Thereisnointeractionbetweenthejoints,thatiseachjointisanalyzedindependentlyfromtheothers,

4. Normalstressesarelinearlydistributedalonghorizontalplanes,5. Shearstressesfollowaparabolicdistributionalonghorizontalplaneintheuncracked

condition.USBR(1976).

2.3.Geometricparametersconsidered

Thedamparametersandreservoirlevelshavebeenreproducedfromthesoftware.

A

B

CD

E

F

G

L1

L3L2

L4

HI

UPSTREAM

DOWNSTREAM

Figure1:Damgeometry


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The dam section had been highlighted in Fig.1.Considering the geometry the dam base

width(L1)is 36.785m.Thecrestwidth of thedam(L3,L4)is 7.5m.The elevation ofpoint F

fromGroundLevelis20.5andtheheightofdamis30.5m.Theweightoftheconcreteis

2630Kg/m3.The Poissons coefficient was 0.2. The dynamic flexibility of the structure is

modeledwiththedynamicconcreteYoungsmodulus(Es)27400MPa.Thedamdampingonrigidfoundationwithoutreservoirinteractionisconsideredtobe0.05.Anychangetothese

basic parametersaffects the fundamental period ofvibration and the dampingof the dam-

foundation-reservoir system. Thus the spectral accelerations are evaluated. The wave

reflectioncoefficient()istheratiooftheamplitudeofthereflectedhydrodynamicpressure

wave to the amplitude of a vertical propagating pressure wave incident on the reservoir

bottom.Avalueof=1indicatesthatpressurewavesarecompletelyreflected,andsmaller

valuesofindicateincreasinglyabsorptivematerials.Thevalueofisconsideredtobe0.5.

Thevelocityofpressurewavesinwaterisinfactthespeedofsoundinwater.Generallyitis

assumed at 1440 m/sec (4720 ft/sec).As considering the reservoir levels the Normal

OperatingLevelisconsideredas26.2mU/sand3.00mD/s.Galleryisatanelevationof

2.00mat3.00mfromtheheelofthedam.Drainefficiencyis0.667.

2.4.Seismicparametersconsidered

InternationalcommitteeonLargeDams,ICOLD(1989)recommendationsarefollowedwhile

evaluating the seismic parameters ;therefore anOperating Basis Earthquake (OBE) and a

MaximumCredibleEarthquake(MCE)areconsidered.TheOBEisdefinedastheground

motion with a 50 percent probability of being exceeded in 100 years. The dam, its

appurtenant structures, and equipment should remain fully operational with minor or no

damage when subjected to earthquake ground motions not exceeding the OBE. The

MaximumDesignEarthquake(MDE)isthemaximumlevelofgroundmotionforwhichthe

concrete dam should be analyzed. The MDE is usually equated to the MCE which, by

definition,is thelargestreasonablypossibleearthquakethatcouldoccuralongarecognized

fault orwithin aparticular seismic source zone. Incaseswhere the dam failure posesno

dangertolifeorwouldnothavesevereeconomicconsequences,anMDElessthantheMCE

maybeusedforeconomicreasons.Krinitzsky(2005)highlightsthataDeterministicSeismic

HazardAnalysis (DSHA) uses geologyandseismichistory to identify earthquake sources

and to interpretthestrongestearthquakeeach source iscapableofproducing regardlessof

time,becausethatearthquakemighthappentomorrow.

AccordingtoUSCOLD(1995),theMCEisthelargestearthquakethatappearspossiblealong

arecognizedfaultunderthepresentlyknownorpresumedtectonicactivity,whichwillcausethemostsevereconsequencestothesite.AnMDEeventshouldbeconsideredasanextreme

loading condition for which significant damage is acceptable, but without a catastrophic

failurecausinglossoflifeorsevereeconomicloss.Theseismicinputisdefinedintermsof

maximumhorizontalaccelerationsandunifiedresponsespectra.

SahuT.(2006)evaluatedthatRegionalRecurrencerelationshipbetweenmagnitude,distance

andgroundaccelerationisusedwhenevaluatingthemaximumhorizontalaccelerationwhich

isbasedontheAssessmentofSeismicHazardforGangrelDam.FortheOBE,areturnperiod

of200yearsisselectedwithaminimumvalueof0.5m/s.FortheMCE,notonlytheresults

ofextreme-valuestatisticsareconsidered,butalsotheglobalgeologyandlong-termtectonic

processesaretakenintoaccount.Theresultinggroundaccelerationscouldbeconsideredasapproximatevaluesonlyand,ingeneral,moredetailedstudiesincludingthelocalgeological


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situationarenecessaryforaspecificsite.Themaximumaccelerationoftheverticalexcitation

isdefinedas2/3oftherespectivemaximumhorizontalacceleration.

Thefirststepintheseismicitystudyofadamsiteistodefinewhetherseismicloadingofthe

structures must be incorporated in to the design or not. The usual basis for this initial

assessmentisthemapofseismicactivity.Sarma(1975)statedthattheabsenceofanyrecordofanearthquakewithin400kmoftheproposedsiteisregardedassufficientjustificationfor

regardingitasaseismic.Thepresenceofearthquakerecordwithinlimiteddistanceindicates

that the Gangrel Dam site is aseismic. The seismic parameters are reproduced from the

softwareandgiveninTable1.

Table1:SeismicCoefficients

Pseudo-static(seismiccoefficient)

HorizontalPeakGround

Acceleration(HPGA)

0.100g Earthquakereturnperiod 200years

VerticalPeakGround

Acceleration(HPGA)

0.0667g Earthquakeaccelrogram

period(te)

1sec

Horizontalsustained

acceleration(HSA)

0.0500g Depthwherepressure

remainsconstant

Generalized

Verticalsustained

acceleration(VSA)

0.0333g Westergaardcorrection

forInclinedsurface

Cornsetal.

2.5.Materialanddesignparametersconsidered

Theclaymaterialavailableinthevicinityofthedamwillprovideahighlyimpermeablefill

forconstructionofthedamcore.Theclaycoreisoflowshearstrengthandofhighlyplastic

consistency.Duetothehighclaycontentoftheproposedclaycorefill,severalfilterzonesoramulti stable filterwill be required to prevent piping in to the rock fill shells.Different

laboratory and field tests have been carried out to estimate shear strength parameters as

describedinTable2.

Table2:Materialproperties

LiftJointMaterialPropertiesMaterial

NameConcreteStrength PeakFriction ResidualFriction Minimal

compressivestress

forcohesion(kPa)

Fc(kPa) Ft(kPa) Cohesion(kPa)

Angle(deg)

Cohesion(kPa)

Angle(deg)

Base

joint

30000 0 0 55 0 45 0

Joint 30000 0 0 55 0 45 0

3.Pseudostaticseismicanalysis(Seismiccoefficientmethod)

Pseudostaticanalysisissimilartothestaticlimitequilibriumanalysisroutinelyconductedby

geotechnicalengineers. Itproducesa scalar indexofstability (the factorofsafety) that is

analogous to that produced by static stability analyses. The inertia forces induced by the

earthquakeare computed from the product of themassand the acceleration.The dynamicamplificationofinertiaforcesalongtheheightofthedamduetoitsflexibilityisneglected.In


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thepseudo-staticmethodofseismicstabilityanalysis,someempiricalvaluesareadoptedfor

thedesignseismiccoefficient; typically thislies in therangeof0.05-0.15.Sahu,T(1996)

calculated the PGA value forGangrel dam as .05gwhich has beenused for the analysis.

WestergaardH.M.,(1933)methodofHydrodynamicanalysisisconsidered.

4.Analysisandresults

StabilityAnalysisofthedamsectionhasbeenperformedusingCADAMwiththeparameters

ofthedamasinput.Thedamsectionhasbeencheckedforvariousloadcombinations.The

resultofstressandstabilityanalysisforusualcombinationhadbeenpresentedthroughTable

3 and Table4 respectivelywhereas Table 5 and Table6 depicts the results of stress and

stabilityanalysisforfloodcombination.Itisevidentfromtheresultsthatthestressarewithin

thepermissiblelimitsonallthejointsandtheFactorofsafetyforOverturningandSlidingis

quitehigherthanthedesired/safevaluesasperthecode.Theresultsofstressandstability

analysisforpeakaccelerationvaluesandsustainedaccelerationvaluesforSeismic1(OBE)

hasbeenpresentedthroughTable7-10andseismic2combinationshasbeenfiguredinTable

11-14.Itisobservedthatthedamsectionissafeforallseismiccombinationsandthedamissafeagainststresses,slidingandoverturningatallthejointsconsidered.Theoverallresults

canbe summarized as follows. The dam section is found tobesafe for the presentPGA

valuesof0.1gandnofurtherretrofittingmeasuresarerequiredforthesectionpresently.The

FOS for sliding and overturning are observed as 4.205 for usual combination where as

requiredis3.00.ForfloodcombinationtheFOSisobservedas2.292whereasrequiredis1.1.

Forseismic1combinationFOSis4.779whenrequiredis1.1andforseismic2combinations

itcomestobe4.683.

Table3:Usualcombination(stressanalysis)

Joint Stresses

ID

Upstream

Elevation

(m)

Normalstresses

U/sD/s

(kPa)(kPa)

Allowablestresses

Tensioncompression

Shear

u/smaximumD/s

(kPa)(kPa)

(kPa)

1 30.000 -11.772 -11.772 0.000-9990.000

2 24.000 -134.777 -158.346 0.000-9990.000 0.0004.7480.000

3 18.000 -289.493 -86.880 0.000-9990.000 0.000-6.235124.111

4 12.000 -358.536 -37.175 0.000-9990.000 0.00067.18953.106

5 6.000 -414.216 -62.994 0.000-9990.000 0.00096.91689.99

6 BASE -461.366 -72.030 0.000-9990.000 0.000121.422

102.897

Table4:UsualCombination(stabilityAnalysis)

Joint SafetyFactors Resultants Uplift

ID Upstream

Elevation

Sliding

Peakresidual

Overturning

toward

u/sd/s

Uplifting Normal

kN

Shear

KN

Moment

KN

Position

%of

joint

Final

Force

kN

1 30.000 >100 >100 >100 >100 >100 -88.3 0.0 0.0 50.000

2 24.000 66.126 46.302 48.543 14.711 23.636 -1099.2 23.7 110.5 51.340 48.6

3 18.000 9.022 6.317 16.064 5.846 10.104 -2083.5 329.8 -2069.6 41.028 228.9

4 12.000 5.612 3.929 9.907 4.660 7.528 -3886.4 989.0 -

10332.6

36.465 595.3

5 6.000 4.804 3.364 8.997 4.249 6.968 -6731.9 2001.4 -

23298.2

37.734 1130

6 BASE 4.205 2.944 4.661 3.447 4.626 -9810.6 3332.1 -

43902.1

37.836 2705.5


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Table5:Floodcombination(Stressanalysis)

Joint Stresses

ID

Upstream

Elevation

(m)

Normalstresses

U/sD/s

(kPa)(kPa)

Allowablestresses

TensionCompression

Shear

U/smaximumD/s

(kPa)(kPa)(kPa)

1 30.000 -11.772 -11.772 0.000-15000.00

2 24.000 -112.052 -170.476 0.000-15000.00 0.00015.6960.000

3 18.000 -242.187 -125.111 0.000-15000.00 0.000-7.764178.726

4 12.000 -306.362 -53.818 0.000-15000.00 0.00085.22976.880

5 6.000 -321.925 -54.699 0.000-15000.00 0.00097.48678.140

6 BASE -352.846 -70.962 0.000-15000.00 0.000107.949101.372

Table6:Floodcombination(Stabilityanalysis)Joint SafetyFactors Resultants Uplift

ID Upstream

Elevation

Sliding

Peakresidual

Overturning

toward

U/sD/s

Uplifting Normal

kN

Shear

KN

Moment

KN

Position

%of

joint

Final

Force

kN

1 30.000 >100 >100 >100 >100 >100 -88.3 0.0 0.0 50.000

2 24.000 19.280 13.500 27.237 7.115 13.000 -1059.5 78.5 273.9 53.447 88.3

3 18.000 5.920 4.145 14.130 4.145 8.285 -2033.2 490.5 -1195.9 44.688 279.1

4 12.000 4.087 2.862 4.870 3.264 4.638 -3537.4 1236.1 -8119.9 38.314 972.3

5 6.000 3.683 2.579 2.495 2.436 2.773 -5313.0 2060.1 -

17726.4

38.175 2997.4

6 BASE 3.848 2.694 2.034 2.135 2.292 -7794.9 2893.4 -

31785.6

38.915 6031.4

Table7:Seismic#1combination-Peakaccelerations(Stressanalysis)Joint Stresses

ID

Upstream

Elevation

(m)

Normalstresses

U/sD/s

(kPa)(kPa)

Allowablestresses

Tensioncompression

Shear

U/smaximumD/s

(kPa)(kPa)(kPa)

1 30.000 -12.792 -12.321 0.000-27270.000 0.000-1.7660.000

2 24.000 -185.604 -127.92 0.000-27270.000 0.000-19.9870.000

3 18.000 -393.433 -10.788 0.000-27270.000 0.000-1.33015.411

4 12.000 -459.836 0.000 0.000-27270.000 0.00032.5470.000

5 6.000 -522.819 0.000 0.000-27270.000 0.00052.2940.000

6 BASE -584.284 0.000 0.000-27270.000 0.00070.7860.001

Table8:Seismic#1combination-Peakaccelerations(StabilityAnalysis)Joint SafetyFactors Resultants Uplift

ID Upstream

Elevation

Sliding

Peakresidual

Overturning

toward

U/sD/s

Uplifting Normal

kN

Shear

KN

Moment

KN

Position

%of

joint

Final

Force

kN

1 30.000

15.234 10.667

>

100 >100 >100 -94.2 -8.8 -2.2 49.688

2 24.000

16.802 11.765 9.808 16.993 25.212

-

1175.7 -99.9 -270.4 46.934 48.6

3 18.000

92.486 64.759 4.808 6.805 10.777

-

2237.6 34.6 -3908.5 34.223 228.9

4 12.000

15.133 10.596 4.469 5.288 8.030

-

4185.2 395.0

-

12697.1 30.890 595.3

5 6.000

10.709 7.498 4.736 4.780 7.421

-

7256.1 967.7

-

33568.4 32.794 1130.0

6 BASE

8.841 6.191 3.387 3.861 4.935 -10645 1719.5

-

64646.4 33.019 2705.5Required>1.3000>1.000>1.100>1.100>1.100


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Table9:Seismic#1combination-Sustainedaccelerations(StressAnalysis)

Joint Stresses

ID

Upstream

Elevation

(m)

Normalstresses

U/sD/s

(kPa)(kPa)

Allowable

stresses

TensionCompression

Shear

U/smaximumD/s

(kPa)(kPa)(kPa)

1 30.000 -12.282 -12.047 0.00-27270.000 0.000-0.8830.000

2 24.000 -160.190 -143.13 0.00-27270.000 0.000-7.6190.000

3 18.000 -341.463 -48.834 0.00-27270.000 0.000-3.76369.761

4 12.000 -407.951 -2.972 0.00-27270.000 0.00051.8064.245

5 6.000 -468.449 -27.338 0.00-27270.000 0.00071.08539.054

6 BASE -522.799 -33.283 0.00-27270.000 0.00093.20747.546

Table10:Seismic#1combination-Sustainedaccelerations(StabilityAnalysis)

Table11:Seismic#2combination-Peakaccelerations(StressAnalysis)

Joint Stresses

ID

Upstream

Elevation

(m)

Normalstresses

U/sD/s

(kPa)(kPa)

Allowablestresses

Tension

compression

Shear

U/smaximumD/s

(kPa)(kPa)(kPa)

1 30.000 -12.792 -12.321 0.000-27270.000 0.000-1.7660.000

2 24.000 -185.604 -127.924 0.000-27270.000 0.000-19.9870.000

3 18.000 -393.433 -10.788 0.000-27270.000 0.000-1.33015.411

4 12.000 -459.836 0.000 0.000-27270.000 0.00032.5470.000

5 6.000 -522.819 0.000 0.000-27270.000 0.00052.2940.000

6 BASE -584.284 0.000 0.000-27270.000 0.00070.7860.001

Table12:Seismic#2combination-Peakaccelerations(StabilityAnalysis)Joint SafetyFactors Resultants Uplift

ID Upstream

Elevation

Sliding

Peakresidual

Overturning

toward

U/sD/s

Uplifting Normal

kN

Shear

KN

Moment

KN

Position

%of

joint

Final

Force

kN

1 30.000 29.515 20.667 >100 >100 >100 -91.2 -4.4 -1.1 49.839

2 24.000 42.641 29.857 15.978 15.852 24.424 -1137.5 -38.1 -79.9 49.063 48.6

3 18.000 16.937 11.859 7.285 6.325 10.440 -2160.6 182.2 -2989.1 37.504 228.9

4 12.000

8.329 5.832 6.096 4.974 7.779 -4035.8 692.0

-

13021.1 33.574 595.3

5 6.000

6.728 4.711 6.154 4.515 7.190 -6994.0 1484.6

-

29261.0 35.171 1130.0

6 BASE

5.783 4.049 3.907 3.654 4.780

-

10227.7 2525.8

-

55198.5 35.328 2705.5


ID Upstream

Elevation

Sliding

Peakresidual

Overturning

toward

U/sD/s

Uplifting Normal

kN

Shear

KN

Moment

KN

Position

%ofjoint

Final

ForcekN

1 30.000 29.515 20.667 >100 >100 >100 -91.2 -4.4 -1.1 49.839

2 24.000 42.641 29.857 15.978 15.852 24.424 -1137.5 -38.1 -79.9 49.063 48.6

3 18.000 16.937 11.859 7.285 6.325 10.440 -2160.6 182.2 -2989.1 37.504 228.9

4 12.000 8.329 5.832 6.096 4.974 7.779 -4035.8 692.0 -13021 33.574 595.3

5 6.000 6.728 4.711 6.154 4.515 7.190 -6994.0 1484.6 -29261 35.171 1130.0

6 BASE

5.783 4.049 3.907 3.654 4.780

-

10227.7 2525.8

-

55198.5 35.328 2705.5

Required>1.3000>1.000>1.100>1.100>1.100


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Table13:Seismic#2combination-Sustainedaccelerations(StressAnalysis)

Joint Stresses

ID

Upstream

Elevation

(m)

Normalstresses

U/sD/s

(kPa)(kPa)

Allowablestresses

Tensioncompression

Shear

U/smaximumD/s

(kPa)(kPa)(kPa)

1 30.000 -12.282 -12.047 0.000-27270.000 0.000-0.8830.000

2 24.000 -160.190 -143.13 0.000-27270.000 0.000-7.6190.000

3 18.000 -341.463 -48.834 0.000-27270.000 0.000-3.76369.761

4 12.000 -407.951 -2.972 0.000-27270.000 0.00051.8064.245

5 6.000 -468.449 -27.338 0.000-27270.000 0.00071.08539.054

6 BASE -522.799 -33.283 0.000-27270.000 0.00093.20747.546

Table14:Seismic#2combination-Sustainedaccelerations(StabilityAnalysis)

5.Conclusionsandrecommendations

Results presented in this paper demonstrate that the response of concrete gravity dam-

reservoirsystemsissignificantlyaffectedbyvariousstaticanddynamicloadingparameters.

Thedesigncheckofexistingdamisperformed,forthepresentPGAvalueof0.1g,toassess

whetherseismicupgradingofGangrelDamisnecessaryfromseismicsafetypointofview.It

canbeconcluded from the present studythat the dam section issafe for all possibleload

combinationsandnofurtherretrofittingmeasuresarerequiredforthesection.

6.References

1. Chopra A.K, (2001), Dynamics of Structures Theory and Application to

EarthquakeEngineering.PrenticeHall,2001.

2. Chopra A.K. and Hanchen T.,EACD-3D-96: A Computer program for 3-dimensionalanalysisofconcreteDam,UniversityofCalifornia,Berkeley,California,

ReportNo.UCB/SEMM-96/06,October1996.

3. GuptaI.D,(2002),ThestateoftheartinSeismicHazardAnalysis,ISETJournalofEarthquakeTechnology,39(4),pp311-346.


ID Upstream

Elevation

Sliding

Peakresidual

Overturning

toward

U/sD/s

Uplifting Normal

kN

Shear

KN

Moment

KN

Position

%of

joint

Final

Force

kN

1 30.000 29.515 20.667 >100 >100 >100 -91.2 -4.4 -1.1 49.839

2 24.000 42.641 29.857 15.978 15.852 24.424 -1137.5 -38.1 -79.9 49.063 48.6

3 18.000 16.937 11.859 7.285 6.325 10.440 -2160.6 182.2 -2989.1 37.504 228.9

4 12.000

8.329 5.832 6.096 4.974 7.779 -4035.8 692.0

-

13021.1 33.574 595.3

5 6.000

6.728 4.711 6.154 4.515 7.190 -6994.0 1484.6

-

29261.0 35.171 1130.0

6 BASE

5.783 4.049 3.907 3.654 4.780

-

10227.7 2525.8

-

55198.5 35.328 2705.5

Required>1.3000>1.000>1.100>1.100>1.100


10/10




4. ICOLD, (1989), Selecting Parameters for Large dams-Guidelines andRecommendations,ICOLDCommitteeonSeismicAspectsofLargedams,Bulletin

72.

5. Koltuniuk,R.M.,HVD-8110-MDA-97-4,Non-linearDynamicStructuralAnalysisofHoover Dam Including Modelling of Contraction Joint Opening and ConcreteCracking,BureauofReclamation,September1997.

6. Kramer,StevenL.1996,GeotechnicalEarthquakeEngineering,PrenticeHall,pp653.

7. Krinitzsky,E.L,(1995),Deterministicversusprobabilisticseismichazardanalysisforcriticalstructures,EngGeology,40,pp1-7.

8. Mills,B.L.,HVD-8110-MDA-97-5, Kinematic studies to determine the stability ofpostulated independent concrete blocks indicated by the non-linear analysis of

HooverDamduringSeismicLoading,BureauofReclamation,December1997.

9. NationalResearchCouncil(NRC),(1985),SafetyofDams;FloodandEarthquake

Criteria,WashingtonD.C;NationalAcademyPress.

10. Payne, T.L.HVD-8110-MDA-97-2, Linear Elastic Dynamic Structural Analysisincludingmass in thefoundation forHooverDam,BureauofReclamation,April,

1998.

11. Sahu, Tejram 2006-07, NIT, Raipur, Chhattisgarh, Seismic Hazard Analysis ofGangrelandSondurDamSites,M.Tech.desertation.

12. Sarma S. K. (1975), Seismic stability of earth dams and embankments,Geotechnique,25,pp743-761.

13. United States Committee on Large Dams, (1995), U.S. and World Dam,HydropowerandReservoirStatistics,USCOLDCommitteeonRegisterofDams.

14. USBR,DesignofGravityDams,(1976),Denver:UnitedStatesDepartmentoftheInteriorBureauofReclamation.

15. Westergaard H. M., (1933), Water pressure on dams during earthquakes,TransactionsASCE,98(1835),pp418-433.

Documents

Safety Check of Existing Dam Against Altered Seismic Hazard Conditions MARY JAMES