完整版有关隧道方面外文文献与翻译.docx

完整版有关隧道方面外文文献与翻译.docx

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完整版有关隧道方面外文文献与翻译

Aconvection-conductionmodelforanalysisofthefreeze-thaw

conditionsinthesurroundingrockwallofa

tunnelinpermafrostregions

HEChunxiong（何春雄），

（StateKeyLaboratoryofFrozenSoilEngineering,LanzhouInstituteofGlaciologyand

Geocryology,

ChineseAcademyofSciences,Lanzhou730000,China;DepartmentofAppliedMathematics,

SouthChinaUniversityofTechnology,Guangzhou510640,China）

WUZiwang（吴紫汪）andZHULinnan（朱林楠）

（StatekeyLaboratoryofFrozenSoilEngineering,LanzhouInstituteofGlaciologyand

Geocryology

ChineseAcademyofSciences,Lanzhou730000,China）

ReceivedFebruary8,1999

Abstract

Basedontheanalysesoffundamentalmeteorologicalandhydrogeologicalconditionsatthesiteofatunnelinthecoldregions,acombinedconvection-conductionmodelforairflowinthetunnelandtemperaturefieldinthesurroundinghasbeenconstructed.Usingthemodel,theairtemperaturedistributionintheXiluoqiNo.2Tunnelhasbeensimulatednumerically.Thesimulatedresultsareinagreementwiththedataobserved.Then,basedontheinsituconditionsofsirtemperature,atmosphericpressure,windforce,hydrogeologyandengineeringgeology,theair-temperaturerelationshipbetweenthetemperatureonthesurfaceofthetunnelwallandtheairtemperatureattheentryandexitofthetunnelhasbeenobtained,andthefreeze-thawconditionsattheDabanshanTunnelwhichisnowunderconstructionispredicted.

Keywords:

tunnelincoldregions,convectiveheatexchangeandconduction,freeze-thaw.

AnumberofhighwayandrailwaytunnelshavebeenconstructedinthepermafrostregionsandtheirneighboringareasinChina.Sincethehydrologicalandthermalconditionschangedafteratunnelwasexcavated，thesurroundingwallrockmaterialsoftenfroze,thefrostheavingcauseddamagetothelinerlayersandseepingwaterfrozeintoicediamonds，whichseriouslyinterferedwiththecommunicationandtransportation.SimilarproblemsofthefreezingdamageinthetunnelsalsoappearedinothercountrieslikeRussia,NorwayandJapan.Henceitisurgenttopredictthefreeze-thawconditionsinthesurroundingrockmaterialsandprovideabasisforthedesign，constructionandmaintenanceofnewtunnelsincoldregions.

Manytunnels，constructedincoldregionsortheirneighbouringarea，spassthroughthepartbeneaththepermafrostbase.Afteratunnelisexcavat，edtheoriginalthermodynamicalconditionsinthesurroundingsareandthawdestroyedandreplacedmainlybytheairconnectionswithouttheheatradiation,theconditionsdeterminedprincipallybythetemperatureandvelocityofairflowinthetunnel，thecoefficientsofconvectiveheattransferonthetunnelwall，andthegeothermalheat.Inordertoanalyzeandpredictthefreezeandthawconditionsofthesurroundingwallrockofatunnel，presumingtheaxialvariationsofairflowtemperatureandthecoefficientsofconvectiveheattransfer,LunardinidiscussedthefreezeandthawconditionsbytheapproximateformulaeobtainedbySham-sundarinstudyoffreezingoutsideacirculartubewithaxialvariationsofcoolanttemperature.Wesimulatedthetemperatureconditionsonthesurfaceofatunnelwallvaryingsimilarlytotheperiodicchangesoftheoutsideairtemperature.Infact，thetemperaturesoftheairandthesurroundingwallrockmaterialaffecteachothersowecannotfindthetemperaturevariationsoftheairflowinadvance;furthermore，itisdifficulttoquantifythecoefficientofconvectiveheatexchangeatthesurfaceofthetunnelwall.Thereforeitisnotpracticabletodefinethetemperatureonthesurfaceofthetunnelwallaccordingtotheoutsideairtemperature.Inthispaper,wecombinetheairflowconvectiveheatex-changeandheatconductioninthesurroundingrockmaterialintoonemode，landsimulatethefreeze-thawconditionsofthesurroundingrockmaterialbasedontheinsituconditionsofairtemperature，atmosphericpressure，windforceattheentryandexitofthetunnel，andtheconditionsofhydrogeologyandengineeringgeology.Mathematicalmodel

Inordertoconstructanappropriatemodel,weneedtheinsitufundamentalconditionsasaba-sis.HereweusetheconditionsatthesceneoftheDabanshanTunnel.TheDabanshanTunnelislo-totedonthehighwayfromXiningtoZhangye,southoftheDatongRiver,atanelevationof3754.78-3801.23m,withalengthof1530mandanalignmentfromsouthwesttonortheast.Thetunnelrunsfromthesouthwesttothenortheast.

Sincethemonthly-averageairtemperatureisbeneathO'}Cforeightmonthsatthetunnelsiteeachyearandtheconstructionwouldlastforseveralyears，thesurroundingrockmaterialswouldbecomecoolerduringtheconstruction.Weconcludethat,afterexcavation,thepatternofairflowwoulddependmainlyonthedominantwindspeedattheentryandexit，andtheeffectsofthetemperaturedifferencebetweentheinsideandoutsideofthetunnelwouldbeverysmall.Sincethedominantwinddirectionisnortheastatthetunnelsiteinwinter,theairflowinthetunnelwouldgofromtheexittotheentry.Eventhoughthedominantwindtrendissoutheastlyinsummer,consideringthepressuredifference,thetemperaturedifferenceandthetopographyoftheentryandexi，ttheairflowinthetunnelwouldalsobefromtheexittoentry.Additionally，sincethewindspeedatthetunnelsiteislow，wecouldconsiderthattheairflowwouldbeprincipallylaminar.

Basedonthereasonsmentione，dwesimplifythetunneltoaroundtube，andconsiderthatthe

airflowandtemperaturearesymmetricalabouttheaxisofthetunnel，Ignoringtheinfluenceoftheairtemperatureonthespeedofairflow,weobtainthefollowingequation:

0

ra（/vav亠

X+7★亦…

at/TI^u-z—+（/—+

dt%

wheret,x,rarethetime,axialandradialcoordinates;U,Vareaxialandradialwindspeeds;Tistemperature;pistheeffectivepressure（that,isairpressuredividedbyairdensity）;visthekinematicviscosityofair;aisthethermalconductivityofair;Listhelengthofthetunnel;Ristheequivalentradiusofthetunnelsection;Disthelengthoftimeafterthetunnelconstruction;

Sf（t）,Su（t）arefrozenandthawedpartsinthesurroundingrockmaterialsrespectively;f,uandCf,Cuarethermalconductivitiesandvolumetricthermal

capacitiesinfrozenandthawedpartsrespectively;X=（x,r）,（t）isphasechange

front;Lhisheatlatentoffreezingwater;andToiscriticalfreezingtemperatureofrock（hereweassumeTo=-0.1C）.

2usedforsolvingthemodel

Equation

（1）showsflow.Wefirstsolvethoseconcerningtemperatureatthatthetemperatureofthesurroundingrockdoesnotaffectthespeedofairequationsconcerningthespeedofairflow,andthensolvethoseequationseverytimeelapse.2.1Procedureusedforsolvingthecontinuityandmomentumequations

Sincethefirstthreeequationsin

（1）arenotindependentwederivethesecond

equationbyx

andthethirdequationbyr.Afterpreliminarycalculationweobtainthefollowing

ellipticequationconcerningtheeffectivepressurep:

「艺p,丄空仃肚、J裂工r3r\dr）~t卄升

10

3Uav\2VZ

nJ"Q・

（2）

»0

Thenwesolveequationsin

（1）usingthefollowingprocedures:

（i）AssumethevaluesforU0V0;

（ii）substitutingU0,V0intoeq.

（2）,andsolving

（2）,weobtainp0;

（iii）solvingthefirstandsecondequationsof

（1）,weobtainU0,V1;

（iv）solvingthefirstandthirdequationsof

（1）,weobtainU2,V2;

（v）calculatingthemomentum-averageofU1,v1andU2,v2,weobtainthenew

U0,V0;

thenreturnto（ii）;

（vi）iteratingasaboveuntilthedisparityofthosesolutionsintwoconsecutiveiterationsissufficientlysmallorissatisfied,wethentakethosevaluesofp0U0and

V0astheinitialvaluesforthenextelapseandsolvethoseequationsconcerningthetemperature..

2.2Entiremethodusedforsolvingtheenergyequations

Asmentionedpreviously,thetemperaturefieldofthesurroundingrockandtheairflowaffecteachother.Thusthesurfaceofthetunnelwallisboththeboundaryofthetemperaturefieldinthesurroundingrockandtheboundaryofthetemperaturefieldinairflow.Therefore,itisdifficulttoseparatelyidentifythetemperatureonthetunnelwallsurface,andwecannotindependentlysolvethoseequationsconcerningthetemperatureofairflowandthoseequationsconcerningthetemperatureofthesurroundingrock.Inordertocopewiththisproblem,wesimultaneouslysolvethetwogroupsofequationsbasedonthefactthatatthetunnelwallsurfacebothtemperaturesareequal.Weshouldbearinmindthephasechangewhilesolvingthoseequationsconcerningthetemperatureofthesurroundingrockandtheconvectionwhilesolvingthoseequationsconcerningthetemperatureoftheairflow,andweonlyneedtosmooththoserelativeparametersatthetunnelwallsurface.Thesolvingmethodsfor

theequationswiththephasechangearethesameasinreferenee[3].

2.3Determinationofthermalparametersandinitialandboundaryconditions2.3.1Determinationofthethermalparameters.Usingp=1013.25-0.1088H,wecalculate

PairpressurepatelevationHandcalculatetheairdensityusingformula,

whereTistheyearly-averageabsoluteairtemperatureandGisthehumidityconstantofair.LettingCPbethethermalcapacitywithfixedpressure,thethermalconductivity,andthedynamicviscosityofairflow,wecalculatethethermalconductivityandofthesurroundingrockaredeterminedfromthetunnelsite.

2.3.2Determinationoftheinitialandboundaryconditions.Choosetheobservedmonthlyaveragewindspeedattheentryandexitasboundaryconditionsofwindspeed