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【英文标准名称】:StandardGuideforUsingtheDirectCurrentResistivityMethodforSubsurfaceInvestigation
【原文标准名称】:直流电阻率法探测地下的标准指南
【标准号】:ASTMD6431-1999(2010)
【标准状态】:现行
【国别】:美国
【发布日期】:1999
【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】:D18.01
【标准类型】:(Guide)
【标准水平】:()
【中文主题词】:
【英文主题词】:electricalmethod;geophysics;resistivity;subsurfaceinvestigation;surfacegeophysics;Directcurrentresistivitymethod;Subsurfaceinvestigation--soil/rock
【摘要】:Concepts8212;Theresistivitytechniqueisusedtomeasuretheresistivityofsubsurfacematerials.Althoughtheresistivityofmaterialscanbeagoodindicatorofthetypeofsubsurfacematerialpresent,itisnotauniqueindicator.Whiletheresistivitymethodisusedtomeasuretheresistivityofearthmaterials,itistheinterpreterwho,basedonknowledgeoflocalgeologicconditionsandotherdata,mustinterpretresistivitydataandarriveatareasonablegeologicandhydrologicinterpretation.ParameterBeingMeasuredandRepresentativeValues:Table1showssomegeneraltrendsforresistivityvalues.Fig.2showsrangesinresistivityvaluesforsubsurfacematerials.Materialswitheitheraloweffectiveporosityorthatlackconductiveporefluidshavearelativelyhighresistivity(>1000x2126;m).Thesematerialsincludemassivelimestones,mostunfracturedigneousrocks,unsaturatedunconsolidatedmaterials,andice.Materialsthathavehighporositywithconductiveporefluidsorthatconsistoforcontainclaysusuallyhavelowresistivity.Theseincludeclaysoilandweatheredrock.Materialswhoseporewaterhaslowsalinityhavemoderatelyhighresistivity.Thedependenceofresistivityonwatersaturationisnotlinear.Resistivityincreasesrelativelylittleassaturationdecreasesfrom100%to40-60%andthenincreasesmuchmoreassaturationcontinuestodecrease.AnempiricalrelationshipknownasArchie''sLawdescribestherelationshipbetweenporefluidresistivity,porosity,andbulkresistivity(McNeill(8)).Equipment8212;Geophysicalapparatususedforsurfaceresistivitymeasurementincludesasourceofpower,ameanstomeasurethecurrent,ahighimpedancevoltmeter,electrodestomakecontactwiththeground,andthenecessarycablestoconnecttheelectrodestothepowersourcesandthevoltmeter(Fig.1).Whileresistivitymeasurementscanbemadeusingcommonelectronicinstruments,itisrecommendedthatcommercialresistivityinstrumentsspecificallydesignedforthepurposebeusedforresistivitymeasurementsinthefield.Commonlyusedequipmentincludesthefollowingelements:Asourceofcurrentconsistingofbatteriesoragenerator,Ahigh-impedancevoltmeterorresistivityunit,Metalstakesforthecurrentandpotentialelectrodes,andInsulatedwiretoconnecttogetheralloftheprecedingcomponents.Caremustbetakentoensuregoodelectricalcontactoftheelectrodeswiththeground.Electrodesshouldbedrivenintothegrounduntiltheyareinfirmcontact.Ifconnectionsbetweenelectrodesandtheinsulatedwirearenotwaterproof,caremustbetakentoensurethattheywillnotbeshortedoutbymoisture.Specialwaterproofcablesandconnectorsarerequiredforwetareas.Alargevarietyofresistivitysystemsareavailablefromdifferentmanufacturers.Relativelyinexpensivebattery-poweredunitsareavailableforshallowsurveys.Thecurrentsource(transmitter)andthepotentialmeasurementinstrument(receiver)areoftenassembledintoasingle,portableunit.Insomecases,thetransmitterandreceiverunitsareseparate.Highpowerunitscapableofdeepsurveyworkarepoweredbygenerators.Thecurrentusedindcresistivitysurveysvariesfromafewmilliampstoseveralamps,dependingonthedepthoftheinvestigation.SignalEnhancement8212;Signalenhancementcapabilityisavailableinmanyresistivitysystems.Itisasignificantaidwhenworkinginnoisyareasorwithlowpowersources.Enhancementisaccomplishedbyaddingtheres..........
【中国标准分类号】:P10
【国际标准分类号】:07_060
【页数】:14P.;A4
【正文语种】:英语