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| 标准名称： | 硝酸铈 |
| 中标分类： |
冶金 >>
有色金属及其合金产品 >>
稀有金属及其合金 |
| 替代情况： | 被GB/T 4151-1996代替 |
| 发布日期： | |
| 实施日期： | 1985-01-01 |
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| 页数： | 2页 |
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所属分类： 冶金 有色金属及其合金产品 稀有金属及其合金
【英文标准名称】:StandardTestMethodforDeterminingUnsaturatedandSaturatedHydraulicConductivityinPorousMediabySteady-StateCentrifugation
【原文标准名称】:用稳态离心法测定多孔介质中不饱和和饱和液压传导性的标准试验方法
【标准号】:ASTMD6527-2000(2008)
【标准状态】:现行
【国别】:美国
【发布日期】:2000
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:D18.04
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:centrifugation;flow;hydraulicconductivity;permeability;porosity;porousmedia;rock;SSC-UFA;soil;steady-state;transport;unsaturated;unsaturatedflowapparatus;waterfluxdensity;Centrifugation;Ceramicmaterials/applications;Concrete;Hydrau
【摘要】:Recentresultshavedemonstratedthatdirectmeasurementsofunsaturatedtransportparameters,forexample,hydraulicconductivity,vapordiffusivity,retardationfactors,thermalandelectricalconductivities,andwaterpotential,onsubsurfacematerialsandengineeredsystemsareessentialfordefensiblesitecharacterizationneedsofperformanceassessmentaswellasrestorationordisposalstrategies.Predictivemodelsrequirethetransportpropertiesofrealsystemsthatcanbedifficulttoobtainoverreasonabletimeperiodsusingtraditionalmethods.UsingaSSC-UFAgreatlydecreasesthetimerequiredtoobtaindirectmeasurementsofhydraulicconductivityonunsaturatedsystemsandrelativelyimpermeablematerials.Traditionally,longtimesarerequiredtoattainsteady-stateconditionsanddistributionsofwaterbecausenormalgravitydoesnotprovidealargeenoughdrivingforcerelativetothelowconductivitiesthatcharacterizehighlyunsaturatedconditionsorhighlyimpermeablesaturatedsystems(TestMethodD5084).Pressuretechniquessometimescannotbeeffectiveformeasuringunsaturatedtransportpropertiesbecausetheydonotprovideabodyforceandcannotactontheentirespecimensimultaneouslyunlessthespecimenissaturatedornear-saturated.Abodyforceisaforcethatactsoneverypointwithinthesystemindependentlyofotherforcesorpropertiesofthesystem.Highpressuresusedonsaturatedsystemsofteninducefracturingorgrainrearrangementsandcausecompactionasaresultofhigh-pointstressesthataregeneratedwithinthespecimen.ASSC-UFAdoesnotproducesuchhigh-pointstresses.Therearespecificadvantagestousingcentrifugalforceasafluiddrivingforce.Itisabodyforcesimilartogravityand,therefore,actssimultaneouslyovertheentiresystemandindependentlyofotherdrivingforces,forexample,gravityormatricpotential.Additionally,inaSSC-UFAtheaccelerationcandominateanymatricpotentialgradientsastheDarcydrivingforce.Theuseofsteady-statecentrifugationtomeasuresteady-statehydraulicconductivitieshasrecentlybeendemonstratedonvariousporousmedia(1,2).Severalissuesinvolvingflowinanaccelerationfieldhavebeenraisedandaddressedbypreviousandcurrentresearch(1,4).Thesestudieshaveshownthatcompactionfromaccelerationisnegligibleforsubsurfacesoilsatorneartheirfielddensities.Bulkdensitiesinthesespecimenshaveremainedconstant(x00B1;0.1g/cm3)becausethespecimensarealreadycompactedmorethantheaccelerationcanaffectthem.Thenotableexceptionisstructuredsoils.Specialarrangementsmustbemadetopreservetheirdensities,forexample,theuseofspeedsnotexceedingspecificequivalentstresses.Asanexample,formostSSC-UFAspecimengeometries,theequivalentpressureinthespecimenatarotationspeedof2500rpmisabout2bar.Ifthespecimensignificantlycompactsunderthispressure,alowerspeedmustbeused.Usually,onlyveryfinesoilsatdrybulkdensitieslessthan1.2g/cm3areaproblem.Wholerock,grout,ceramics,orothersolidsarecompletelyunaffectedbytheseaccelerations.PrecompactionrunsuptothehighestspeedforthatrunareperformedintheSSC-UFApriortotheruntoobserveanycompactioneffects.Three-dimensionaldeviationsofthedrivingforceasafunctionofpositioninthespecimenarelessthanafactoroftwo.Theoretically,thesituationunderwhichunitgradientconditionsareachievedinaSSC-UFA,inwhichthechangeinthematricpotentialwithradialdistanceequalszero(dx03C8;/dr=0),isbestathigherwaterfluxdensities,higherspeeds,orcoarsergrain-size,orcombinationthereof.Thisisobservedinpot........
【中国标准分类号】:D04
【国际标准分类号】:07_060
【页数】:10P.;A4
【正文语种】:英语