strain monitoring and stress analysis of a post-prestressed tunnel liner

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1、StrainMonitoringandStressAnalysisofaPost-PrestressedTunnelLinerTransactionsof~anjmUniversityISSN1006?-4982pp215?-221V01.12No.3Jun.2006StrainMonitoringandStressAnalysisofaPost.PrestressedTunnelLinerKANGJingfu(亢景付),WANGJinhui(王金辉)(SchoolofCivilEngineering,Ti蚰jinUniversity,Ti蚰jin3000

2、72,China)Abstract:Thestrainmonitoringandstressanalysisofanewtypeofpost—prestressedtunneIIinerwerecarriedout.TheinstrumentationblockofthetunneIIiner.withthedimensionsof12.06minlength,6500mmindiameter,and650mminthickness,waspost—prestressedwiththeunbondedtendons.eachofwhichconsistso

3、f8piecesofdouble—loopedstrandsandtheaxiaIspacingofthetendonsis500mm.Concretestrainmeters.rebarmeters.IpadcelIandzero—stressmeterswereinstalledforthestrainmonitoring.ThetensioningIpadswereappliedincrementallyinthreecvcles(50%.77%and100%)attheconcreteageof28dandthetensioningworkIast

4、edfor187.1h.StrainreadingsweretakenbeforeandaftereachcycleduringtensioningperiodandatthespecifiedtimeintervaIaftertensioningperiod.Itisfoundthatconcretecreepdevelopedovertensioningperiodis30%oftotaIstrainand41.5%ofelasticstrainrespectively.Prestressforceintheunbondedtendonandconcr

5、etestressintheIinerwereevaluatedaccordingtotheobsewedstrainvariations.Bothofthemaretime-dependent.andabout5.3%.8.3%and9.0%oftheprestressIossesareobsewedattheageof1d.30dand60drespectivelyafterstressing.ThedistributionofprestressintheIinerisrelativelyunifOrmandmeetsthedesignrequirem

6、ent.Keywords:hydraulicstructure;concretecreep;tensioningperiod;instrumentation:elasticstressEffectiveprestressandthestressdevelopmentarestressing.widelyconcernedforprestressedconcretestructures.Manyinstmmentssuchasconcretes仃ainmetersand1Fieldinstrumentationsrebarmetersareofteninst

7、alledtomonitorthedevelop—mentsofconcretestresslJ.Thereadingstakenfrombothconcretestrainmetersandrebarmetersaretotalstrain,whichisasumofelasticstrain,concretecreepstrain,andthestrainscausedbytemperaturevariation,concreteshrinkageandtendonsrelaxation.Itisimpo~anttotakeapartthemoneby

8、one,espe—cialb~theconcreteelastic