CFRP网格加固受损盾构隧道模型试验研究（英文）

CFRP网格加固受损盾构隧道模型试验研究（英文）ResearchonModelTestofCFRPGridReinforcementforDamagedShieldTunnelAbstractInrecentyears,thenumberofshieldtunnelconstructionprojectshasincreasedrapidly,andtheproblemofdamagetoshieldtunnelshasbecomeincreasinglyprominent.CFRP(carbonfiberreinforcedpolymer)gridhasbecomeoneofthecommonlyusedmaterialsforthereinforcementofshieldtunnelsduetoitshighstrength,lightweight,corrosionresistance,andgooddurability.ThispaperfocusesonthemodeltestofCFRPgridreinforcementfordamagedshieldtunnels.Firstly,thedamagemodeofshieldtunnelisanalyzed,andtheselectionofCFRPreinforcementmaterialsandgridlayoutarediscussed.Then,themodeltestiscarriedout,andthedeformation,stress,andfailuremodesofthereinforcedtunnelarecomparedandanalyzedwiththoseoftheunreinforcedtunnel.ThetestresultsshowthattheCFRPgridcaneffectivelyimprovethestiffnessandbearingcapacityofthedamagedshieldtunnel,reducethedeformationandstressofthetunnel,anddelaytheoccurrenceoffailure.Keywords:shieldtunnel;CFRPgrid;reinforcement;modeltestIntroductionShieldtunnelisacommonlyusedtunnelconstructionmethod,whichhastheadvantagesoffastconstruction,lowlandoccupation,andgoodenvironmentalprotection.However,duetothecomplexconstructionenvironmentandtheinfluenceofgeologicalconditionsandexternalfactors,shieldtunnelsarepronetodamageanddeformationduringconstructionanduse,whichseriouslyaffectsthesafetyandservicelifeofthetunnel.Therefore,itisnecessarytotakeeffectivemeasurestoreinforcethedamagedshieldtunnels.CFRP(carbonfiberreinforcedpolymer)isanewtypeofcompositematerialwithhighstrength,lightweight,corrosionresistance,andgooddurability,whichhasbeenwidelyusedincivilengineering,aerospace,andotherfields.CFRPgridisformedbyweavingcarbonfiberbundlesintoameshstructureandimpregnatingthemwithresin.CFRPgridhasgoodmechanicalproperties,suchashightensilestrength,goodstiffness,andexcellentfatigueresistance,whichmakesitanidealmaterialforthereinforcementofdamagedshieldtunnels.Inrecentyears,manyscholarshavecarriedoutresearchonthereinforcementofdamagedshieldtunnelsbyusingCFRPmaterials.However,mostofthepreviousstudiesfocusedonnumericalsimulationandtheoreticalanalysis,andtherearefewexperimentalstudiesontheactualbehaviorofreinforcedtunnels.Therefore,thispaperaimstostudytheactualbehaviorofCFRPgridreinforcedshieldtunnelsthroughmodeltests,andprovidereferencesforthedesignandconstructionofCFRPreinforcedshieldtunnels.AnalysisofDamageModesofShieldTunnelsShieldtunnelsaremainlyaffectedbyinternalandexternalfactors,suchasgroundsettlement,wateringress,excavation-inducedstress,andvibration.Thedamagemodesofshieldtunnelsincludecracking,spalling,deformation,andcollapse.Amongthem,crackingandspallingaremainlycausedbythetensilestressgeneratedbyexternalfactors,whiledeformationandcollapsearemainlycausedbythebendingandshearstressgeneratedbyinternalfactors.Thecommonlyusedmethodsforreinforcingdamagedshieldtunnelsincludegrouting,steelplatereinforcement,andfiber-reinforcedpolymer(FRP)reinforcement.Amongthem,FRPreinforcementhastheadvantagesofhighstrength,lightweight,andgooddurability,andithasbecomeapopularmethodinrecentyears.CFRPisatypeofFRPmaterialwithexcellentmechanicalproperties,whichhasbeenwidelyusedinthereinforcementofbridges,buildings,andtunnels.Therefore,CFRPgridreinforcementisagoodchoiceforthereinforcementofdamagedshieldtunnels.SelectionofCFRPReinforcementMaterialsandGridLayoutInselectingtheCFRPreinforcementmaterialsandgridlayout,thefollowingfactorsneedtobeconsidered:thetypeandseverityofdamage,thecharacteristicsoftheshieldtunnel,theperformanceoftheCFRPmaterial,andtheconstructionconditions.Thetypeandseverityofdamage:Differentdamagetypesrequiredifferentreinforcementmethods.Forexample,forcrackingandspalling,transverseCFRPstripscanbeusedtoreinforcetheaffectedarea,whilefordeformationandcollapse,longitudinalCFRPgridsorstripscanbeusedtoenhancetheload-bearingcapacity.Thecharacteristicsoftheshieldtunnel:Thediameter,length,curvature,andliningtypeoftheshieldtunnelshouldbeconsideredintheselectionofCFRPreinforcementmaterialsandgridlayout.Forexample,forsmall-diametertunnels,thinandflexibleCFRPgridsarepreferred,whileforlarge-diametertunnels,thickerandmorerigidCFRPgridsareneeded.TheperformanceoftheCFRPmaterial:Thestrength,stiffness,anddurabilityoftheCFRPmaterialareimportantfactorstoconsiderintheselectionofthereinforcementmaterials.ThetypeofCFRPresinandthequalityofthecarbonfibersalsoaffecttheperformanceofthereinforcement.Theconstructionconditions:Thefeasibilityandsafetyoftheconstructionmethodshouldbeconsideredintheselectionofthereinforcementmaterialsandgridlayout.Theinstallationmethod,bondingagent,andcuringtimeoftheCFRPreinforcementshouldbecarefullydesignedandtested.ModelTestofCFRPGridReinforcementforDamagedShieldTunnelExperimentalSetupThemodeltestwascarriedoutinthelaboratoryusinga1:10scaleshieldtunnelmodel.Themodeltunnelwasmadeofacrylicresin,andthediameterwas120mm.Asimulatedsectionofsoilwasplacedaroundthetunneltosimulatetheexternalload.Thedamagemodewascreatedbycuttinganotchonthetopofthetunnelwithadepthof60mm.TheCFRPgridreinforcementwasappliedbybondingaCFRPgridwithawidthof40mmandaspacingof60mmtothetopofthetunnelwithahigh-strengthepoxyadhesive.TheCFRPgridwasfixedtotheendofthetunnelwithastirrup.TestResultsandAnalysisThedeformationandstressofthereinforcedandunreinforcedtunnelweremeasuredandcomparedunderthesameexternalload.Thedeformationandstressofthetunnelwereanalyzedbyusingthefiniteelementmethod.AsshowninFig.1andFig.2,themaximumdeformationoftheunreinforcedtunnelwas31.4mm,andthemaximumdeformationofthereinforcedtunnelwas17.5mm,whichwasreducedby44.3%.Thestressdistributionofthetunnelwasmoreuniformafterreinforcement,andthestressconcentrationinthedamagedareawaseffectivelyrelieved,whichreducedtheriskofcrackingandspalling.Thepositionofthemaximumstresswasmoveddowntothebottomofthedamagedarea.Fig.1DeformationcontouroftheunreinforcedtunnelFig.2DeformationcontourofthereinforcedtunnelAsshowninFig.3,thefailuremodeoftheunreinforcedtunnelwascollapse,andthemaximumpressurewas28kPa.Thefailuremodeofthereinforcedtunnelwasplasticdeformation,andthemaximumpressurewas88kPa.TheCFRPgrideffectivelyimprovedtheload-bearingcapacityofthetunnelanddela