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中國礦業(yè)大學(xué)2012屆本科生畢業(yè)設(shè)計(jì) 一般部分中國礦業(yè)大學(xué)2012屆本科生畢業(yè)設(shè)計(jì) 第頁英文原文Self-boringpressuremeterpermeabilitymeasurementsinBothkennarclayS.RATNAM,K.SOGA,R.J.MAIRandR.W.WHITTLEKEYWORDS:clays;earthpressure;insitutesting;permeability;porepressures,siteinvestigationINTRODUCTIONThesemeasurementswerecarriedoutaspartofanongoingresearchcollaborationbetweentheCambridgeUniversityEngineeringDepartment(CUED)andCambridgeInsitu(CI).Theprojectiscentredonthedevelopmentofaself-boringpressure-meter(SBP)systemcapableofmeasuringpermeabilityasoneofanumberoffundamentalsoilpropertiesfromasingleselfboringtest.TheSBPoftheCambridgedesignwasdevelopedinthe1970stocarryoutminimaldisturbancein-situtestsonsoilforobtaininghigh-qualityin-situstrength,stiffnessandhorizontalstressparameters(Wroth&Hughes,1972).Thesamedevicecanalsobeusedtoobtainanindirectestimateofpermeabilityfromadissipation-type`holding'test(Clarkeetal.,1979).ThisnewmethodisreferredtoastheMarkIImethod(MKII);itallowsforadirectmeasurementofpermeabilitytobemadeinadditiontothepreviouslymentionedmeasurementsusingthesameinstrument(Ratnametal.,2001a).ThisdirectmeasurementusesaSBPdevice,andisdistinctfromself-boringpermeametertests(e.g.Leroueiletal.,1992;Gourvenacetal.,1999).ThemethodhasbeenpreviouslytestedbothinstiffGaultclaynearCambridge(Ratnametal.,2000)andinanengineeredcementbentonitecut-offwallonacontaminatedsite(Ratnametal.,2001c).TheBothkennarsitewaschosentofurthervalidatethefeasibilityoftheMKIImethod,particularlyinasoftclaydeposit.Thiswaspossiblebecauseoftheextensiveassessmentofpermeabilityatthesite(Leroueiletal.,1992).Inaddition,thesetestsprovidedtheopportunitytocompareSBPtestdata

usinganewnon-linearmethod(Bolton&Whittle,1999)withdatafrompreviousinvestigationsusingconventionalanalysis.BACKGROUNDTheBothkennarsite,locatedbetweenEdinburghandGlas-gowandadjacenttotheRiverForthinScotland,wasestablishedin1987bytheEngineeringandPhysicalSciencesResearchCouncil(EPSRC)forresearchintosoftclayengineering.Priortoitsuseforotherresearch,thesitewasthoroughlycharacterisedusingthemostsophisticatedtestingmethodsavailableatthattime(Hightetal.,1992).Thiswasinadditiontotheinitialinvestigationsconductedpriortothepurchaseofthesite(Nashetal.,1992).AseriesofSBPtestswasconductedaspartoftheinitialinvestigations.ThetestsweredonebyPMInsituLtd.andwereatintervalsofapproximately1mtoadepthofabout20m,inasingleborehole(PR1)nearthesouthboundary(seeFig.1).Permeabilitytestingwasnotundertakenintheseinitialinvestigations.Subsequently,duringthesitecharacterisationstudies,in-situpermeabilitytestingwasconductedbyLavalUniversityusingtheirself-boringpermeameter(PERMAC)andpush-inpiezometers,andbytheBuildingResearchEstablishment(BRE)usingapushed-inBATsystem(Leroueiletal.,1992).Thecharacterisationstudyareaislocatedtothenorth-westofbore-holePR1inFig.1.ThePERMACworkwasconductedintwoboreholes(SBP1and2)whilefivepush-inpiezometers(PZ1-5),pushedtodepthsof3,6,9,12and15m,werelocatedinanorthtosouthline,totheeastoftheself-boredlocations(Hightetal.,1992).ThePERMACtestingwasconductedat3mintervalsbetween3mand15musingtwotestcavityaspectratiosateachtestdepth.ThePERMACinstrumentwaswith-drawnfromtheboreholeinordertoalteritstestcavityaspectratio(L=d),whichisafunctionofthecavityorpocketlength,L,anddiameter,d.InterchangeablepartswereusedtogiveL=dratiosof2and4withthissystem.ThePERMACdeviceisapurpose-builtself-boringpermeameter,whichiscapableofmeasuringonlypermeability.Pressuremetertestswerethereforenotmadeintheseboreholes.Othertypesoftestingandinvestigationsatthesitearediscussedelsewhere(Hightetal.,1992;Nashetal.,1992),andwillnotbeconsideredfurtherhere.Fig.1.Locationofpreviousinvestigations(afterHightetal.,1992)SOILPROFILEANDGEOTECHNICALPROPERTIESNashetal.(1992)reportthattheclayisgenerallyuniformacrossthesiteapartfromthesouth-eastcorner,whereitishighlylaminated(eastofP18inFig.1).Thegroundwaterintheclayishydrostatic,withthewatertableabout0.5mbelowground.Leroueiletal.(1992)summariseanddiscusssomeofthegeotechnicalindexpropertiesoftheclay,andalsothefabricprofileatthesite,thathavesomebearingonhydrauliccon-ductivity(Fig.2).Themoisturecontenthasbeennotedtovaryconsiderablybothacrossthesiteandwithdepth(Nashetal.,1992).WhilethecompositionoflithologicalunitsL2,L3andL4isconsideredtoberelativelyuniform,thepresenceoffabricfeaturesshowninFig.2isworthnoting,andisofparticularrelevancetopermeabilitymeasurement.TESTPROGRAMMEOveraperiodoffivedays,inOctober2000,atotalofsixteenMKIIpermeabilitytestsandeightSBPtestswereconductedinasingleboreholeatthesite.FouroftheeightSBPtestswereholdingtests.Theborehole,SBP3,waslocatedadjacenttothecharacterisationarea(seeFig.1).Followingself-boring,theMKIIteststartsataconditionwherethetipoftheinstrumentisflushagainstthebottomoftheborehole.Anadapterisfixedtothetopofthedrillstring,andfuidisdeliveredataconstantflowratetothetipoftheinstrumentviathesamepathwaythroughwhichthedrillingfluidisdeliveredduringself-boring.Constantflowinjectionisperformeduntilasteadystateisreached,andtheflowrateisthenincreased.Usingasetofsteady-statepressureswithcorrespondingconstantflowrates,alinearplotisestablished.TheinverseoftheslopeoftheplotisusedtodeterminethemeasuredcoefficientofpermeabilityfromKm=Q/FH,whereQistheflowundersteady-stateconditions,HistheappliedheadofwaterandFisthegeometryshapefactor.Theprobeisthenpulledbackashortdistance,leavingadefinedpocketinthegroundtoperformadditionaltestsforthenewL/dgeometry.IftestsareconductedfortwoormorecavityL/dratios,theverticalandhorizontalcoefficientsofpermeability,KvandKhrespectively,canbededucedfromthemeasuredpermeability,Km.ConductingtestsatseveralL/dratiosthusallowstheeffectofincreasingsamplesizeonpermeabilitytobedetermined.Typically,aboutfoursteadystatesforaparticularL/dcanbeestablishedwithinanhouroftesting.TheMKIItestprocedureisoutlinedindetailinRatnam(1999),Ratnametal.(2000)andRatnametal.(2001b),andtheSBPtestisdescribedinWroth&Hughes(1972)andBolton&Whittle(1999).TheholdingtestprocedureisdiscussedinClarkeetal.(1979).TheMKIItestswereperformedatapproximately3mintervals,between3mand12m.ThesetestdepthsaresimilartotheearlierPERMACtestdepths.AsoftgroundconfigurationoftheSBP,withthecutterlocatedwithintheshoeedge,wasusedtogetherwithaportabledrillingset-up.Theinstrumentdiameter,d,was0.083m.Detailsoftheportableset-upandequipmentaregivenelsewhere(Ratnametal.,2001b).ThesequenceoftestingisillustratedinFig.3.Ingeneral,anSBPtestwasfirstcarriedout,andthentheinstrumentwasdrilledontotheMKIItestlevel,wheretheL=0(zerolengthcavity)testwasfirstconducted.TheinstrumentwasthenpulledbackinstagestocreateshortlengthsofunsupportedcavityfortheL/dratio1,2and4MKIItests,respectively.Thissequencewastypicallyaccomplishedinaday.Thefollowingmorning,theinstrumentwasdrilledonandaholdingtestwasperformedataboutthesamedepthasthepreviousL=0test.TheholdingtestswereatapproximatelythesamedepthsastheMKIItestleveltoprovideacomparisonofdirectandindirectpermeabilitymeasurements.TheSBPandholdingtestdepthswere0.5mbehindthetipoftheshoeedge,atthecentreoftheporepressurecellsandexpandedmembrane.SubsequentSBPtestswereconductedawayfromthezoneofinfluenceofthepreviousMKIItest.Alltestswereconductedinasingleself-boringoperation,usingthesameinstrument,withouttheneedforcompletelyretractingtheinstrumentfromtheborehole.ThelogoftestsconductedinboreholeSBP3issummarisedinFig.4.AconcernwhentestinginsoftclaydepositsisthattheboreholewillnotremainopenwhentheinstrumentisretractedforL/d>0tests.ThiswasnotaproblemwithtestsconductedpreviouslyinstiffGaultclay(Ratnam,1999).Undrainedstabilitycalculations,similartothoseusedfortunnelheadingsinsoftground(Mair,1979),assumingisotropicconditionsinBothkennarclay,indicatedfairlyhighfactorsofsafetyforafullysubmergedborehole:thatis,whentheboreholewasfullofwater.Thiswaslaterverifiedbyfieldobservations.Theunsupportedcavity,typicallyatL/d=2or4,wasleftovernightaftertesting,anddrillingdowntotheholdingtestdepthwasonlycommencedthefollowingmorning.Whentheinstrumentrepenetratedthecavityarea,noclaycuttingswerereturnedinthedrillwater.AssoonasfreshmaterialwasencounteredbeyondtheL=0level,cuttingswereobserved.Theintegrityofthecavityduringandforuptoatleast15hoursaftertestingwasthereforeconformed.Fig.2.GeotechnicalpropertiesandfabricprofileFig.3.TestsequenceinBothkennarclayFig.4.BoreholeSBP3testlogFig.5.SampleMKIIdatasetfrom6mdepthinboreholeSBP3:(a)steady-statepressuresforL=d1(P3T5),at6mdepth;(b)variouslinearrelationshipsat6mdepthMKIITESTRESULTSAlthoughonlytwoflowrates(andthecorrespondingsteady-stateporepressures)areneededtodefinethelinearrelationship,asdescribedabove,foreachL/dratioseveralflowrateswereattemptedtocheckitslinearity.Forexample,forL/d=1,fivesteady-statepressureswereestablished(Fig.5(a)).ThelinearrelationshipwasalsodeterminedforvariousL/dratiosateachtestdepthlevel.AtypicaldatasetisshowninFig.5.Asthesamplesizeincreases,otherfeaturessuchasthosedescribedinthefabriclog(Fig.2)areincreasinglyincludedinthetestedarea.Mostofthesefeatures,suchasthefissuringandsandlaminae,tendtoincreasethemeasuredpermeabilityasthesamplesizeincreasesandincorporatesthesefeatures.Thisis

reflectedbythegradualflatteningoftheslopeofthelinearrelationshipsshowninFig.5(b).NotethattheinverseoftheslopeisusedinKm=Q/FH.Themeasuredpermeabilitydataarerelatedtothehorizontalandverticalcoefficientsofpermeability,KhandKv,usingtherelationshipUsingthisrelationshipandassumingananisotropyratioRk=Kh/Kv=2,asdeterminedfromlaboratorystudiesbyothers(Leroueiletal.,1992),thedatawerefurtherinterpretedtoreflectKhandKv,andcomparedwithdatafrompreviousinvestigationsatthesite(Fig.6).Forclarity,onlyKhfromL=d/2and4MKIIdataandKvfromL/d=0and1MKIIdataareshowninFig.6(a)and(b)respectively.TheMKIIdataforKhshowninFig.6(a)generallyplothigherthanthepiezometer,BATandPERMACdata.TheauthorsagreewithLeroueiletal.(1992)thatthesmearingandreconsolidationassociatedwithpushed-inelements(e.g.piezo-meters/BATsystem)leadtoanunderestimateofpermeability.ItisinterestingtonotethatthedifferencebetweentheL/d=2andL/d=4dataislessprominentforthePERMACthanfortheMKIImethods.ThesmallerdifferencebetweenthePERMACresultscouldbeattributedtothesmallerdiameterofthePERMACdevice(0′073m),totheoccurrenceofsmearingwhentheinstrumentisretractedandreinsertedforL/d=4,orsimplytothevariabilityofthefabric.ThereisfaircorrelationbetweentheMKIIandlargediameterlaboratorytestresults.Figure6(a)alsoshowsthatthereisreasonableagreementbetweentheholdingtestdatafromthisseriesandinitialinvestigationsinboreholePR1.TheearlierdataareinterpretedfromClarke(1990).Previousmethodswerenotabletoobtainadirectin-situmeasurementofKv,unliketheMKIImethodfromtheL=0testandtestsatsubsequentL/dratios.TheMKIIKvdatacouldthereforeonlybecomparedwiththelaboratoryKvdata(Fig.6(b)).Reasonableagreementisobserved,andthereislessvariabilityintheKvdata,suggestingalesserinfluenceoffabricforlowintheverticaldirection,whichisexpected.Fig.6.ComparisonofMKIIdataanddatafromothers:(a)Kh;

(b)KvSBPTESTRESULTSTheSBPtestdatawereanalysedusingthenewBolton&Whittle(1999)non-linearelasticsolutionforanundrainedcavityexpansion.Thelateralearthpressurecoefficient,Ko,belowtheinitialcrustwasdeterminedtobeabout1.ThisagreeswithearlierdatapresentedinShuttle&Jefferies(1995).DerivedvaluesforundrainedshearstrengtharealsoinagreementwithpreviousSBPtests(Fig.7(a)).TheygenerallyplothigherthanthelaboratoryandfieldvanedatafromNashetal.(1992),whichistypicalandwidelyacknowledged(Mair&Wood,1987).Fig.7(b)showsthemeasuredsecantshearmodulus,Gs,atvariousvaluesofshearstrain.Themodulusvalueshavebeennormalisedtotheeffectivecavityreferencepressure.AsreportedbyHightetal.(1992),atlargestrain,normalisationseemstoremovemostoftheinfluenceofdepth.ValuesofthecoefficientofconsolidationfromtheholdingtestwereconvertedtopermeabilityparametersusingGswithanassumedPoisson'sratioof0.3forthedrainedcondition.ThesedataareplottedwithotherpermeabilityresultsinFig.6(a).Fig.7.SBPundrainedtestresults:(a)undrainedshearstrength;(b)secantshearmodulusCONCLUSIONTheMKIImethodofdirectpermeabilitymeasurementwassuccessfullydemonstratedattheBothkennarsoftclaytestsiteusingaconventionalSBPoftheCambridgedesign.Measurementsusingthistechniquecomparedwellwithresultsfromothermethods.Inadditiontopermeabilitymeasurement,conventionalexpansionpressuremetertestsandholdingtestswerealsoconducted,andtheresultswereshowntocorrespondwellwithearlierdataatthesite.ThepotentialfortheSBPasamulti-parametersiteinvestigationtoolhasbeendemonstrated.ACKNOWLEDGEMENTSTheauthorswouldliketoacknowledgethePrimeMinister'sFellowshipExchangeProgram(Malaysia),whichprovidesthePerdanaScholarshiptowardsthefirstauthor'sPhDstudies,andalsotheassistancereceivedfromtheEPSRCandBRE,particularlyinrelationtotheuseoftheBothkennarsite.REFERENCES

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[13]Ratnam,S.,Soga,K.,Mair,R.J.,Whittle,R.W.&Tedd,P.(2001c).Aninsitupermeabilitymeasurementtechniqueforcut-offwallsusingtheCambridgeself-boringpressuremeter.Proc.15thInt.Conf.SoilMech.GEngng,Istanbul.[14]Shuttle,D.A.&Jefferies,M.G.(1995).ReliableparametersfromimperfectSBPtestsinclay.ProceedingsICEinternationalconferenceonadvancesinsiteinvestigationpractice,pp.571-585.London:ThomasTelford.[15]Wroth,C.P.&Hughes,J.M.O.(1972).Aninstrumentfortheinsitumeasurementofthepropertiesofsoftclays,ReportCUED/D,SoilsTR13.UniversityofCambridge.中文譯文自傳式旁壓儀在波斯肯納粘土中的滲透性測量關(guān)鍵詞:粘土地球壓力施工現(xiàn)場測試滲透性毛孔壓力基地勘探引言這些測量結(jié)果被作為劍橋大學(xué)工程系(線索)和劍橋Insitu公司(CI)之間正在進(jìn)行的合作研究的一部分。該項(xiàng)目以自轉(zhuǎn)式旁壓儀系統(tǒng)能夠從單一光速指示器測試的基本土壤性質(zhì)為中心。自傳式旁壓儀是20世紀(jì)70年代劍橋設(shè)計(jì)進(jìn)行對土壤的原位測試獲得高品質(zhì)的原位強(qiáng)度,剛度和水平應(yīng)力參數(shù)時(shí)發(fā)展起來的。(沃斯和休斯1972年)同樣的設(shè)備也可以被用來獲取滲透率的間接估計(jì),從耗散型”控股”測試(克拉克伊特爾,1979年)。這種新方法被稱為MarkII方法。它允許一個(gè)除了前面提到的測量,使用相同的儀器(拉特納姆,2001年)滲透率進(jìn)行直接測量,這種直接測量使用自傳式旁壓儀,不同于其他自傳式滲透儀測試(例如洛爾萊等1999年)。該方法無論是在劍橋附近的僵硬爾特粘土還是被選定的用于隔斷污染場地的工程水泥膨潤土都已被提前的測試。波斯肯納基地是為了進(jìn)一步驗(yàn)證MKII的方法的可行性而選出來的,特別在軟粘土礦床。這是由在現(xiàn)場(Leroueil,1992年)的廣泛滲透評估。此外,這些測試提供了用一個(gè)新的非線性方法比較自傳式旁壓儀測試數(shù)據(jù)的機(jī)會(博爾頓,惠特爾,1999年)。背景波斯肯納基地由研究軟粘土工程由工程和物理科學(xué)研究理事會(EPSRC)成立于1987年,位于愛丁堡和格拉斯之間,毗鄰在蘇格蘭的福斯河。這個(gè)基地的使用優(yōu)于它在其他實(shí)驗(yàn)的使用,因?yàn)樗耆厥褂米钕冗M(jìn)的測試方法為特點(diǎn),這是除了購買該基地之前進(jìn)行的初步調(diào)查。一系列自傳式旁壓儀的測試是初步調(diào)查的一部分。由PM有限公司進(jìn)行測試間隔約1米的深度大約20米,在單一鉆孔附近南邊界(見圖一)。滲透性測試并不在這些初步調(diào)查中進(jìn)行。此后,在基地特性研究中,包括由拉瓦爾大學(xué)進(jìn)行了原位滲透測試使用的他們的自傳式旁壓儀和壓力計(jì),還有由建筑研究所堆積的批文件系統(tǒng)。研究區(qū)位于西北部鉆孔。自傳式旁壓儀在兩個(gè)鉆孔中進(jìn)行(SBP的1和2)工作,并用五名推壓力計(jì)(PZ1-5),分別推到3,6,9,12和15米的深度,設(shè)由北到南線,自鉆孔的東部位置。自傳式磁導(dǎo)儀測試是在3米和15米之間沒間隔3米測試該深度使用兩個(gè)測試腔的長寬比。該儀器來自鉆孔以改變其測試洞長寬比(L=D),這是一個(gè)可以測試洞的長度L和自傳式旁壓儀直徑D的功能??苫Q零件使這個(gè)系統(tǒng)L/D比值等于2到4。自傳式旁壓儀設(shè)備是一個(gè)專用的自鉆滲透儀,可進(jìn)行滲透性壓力測試,因此旁壓測試并不僅僅用于這些鉆孔中。在現(xiàn)場測試和調(diào)查的其他類型的其他地方討論,在這里將不予進(jìn)一步考慮。圖一以前的調(diào)研區(qū)土壤剖面及工程性質(zhì)納什等專家在報(bào)告中指出這種粘土一般凝結(jié)在層壓大的基地東南角。在粘土中的地下水是靜壓水,水位低于地面約0.5米。雷若爾等人總結(jié)和討論一些粘土的巖土工程性能指標(biāo)和建筑的基地配置文件,還有一些軸承,液壓導(dǎo)率等(圖2)。已經(jīng)注意到整個(gè)基地不同深度的地方含水量大都不同。雖然L2,L3和L4巖性單位組成被認(rèn)為是相對統(tǒng)一的,值得注意的是,在圖2所示的建筑功能的存在,是特別相關(guān)的透氣性測量。測試項(xiàng)目2000年10月,在五天的周期內(nèi),一系列包括16項(xiàng)MKII可滲透性測試和8項(xiàng)SBP測試在一個(gè)單一鉆孔內(nèi)進(jìn)行了試驗(yàn),八項(xiàng)SBP測試中有四項(xiàng)用作對比測試。鉆孔SBP3位置鄰近于特征地區(qū)(見表1)。繼承于自轉(zhuǎn)式旁壓儀,MKII測試是在機(jī)器的頂端緊壓著鉆孔底部的條件下進(jìn)行的。一個(gè)傳感器被固定在鉆頭的頂部,并且液壓油通過與鉆機(jī)自轉(zhuǎn)時(shí)鉆桿潤滑油輸送途徑一樣的路徑以固定的流動(dòng)速度輸送到儀器的頂部。液壓油會一直注入直到達(dá)到一種穩(wěn)定狀態(tài),并且流動(dòng)速度也會隨之加快。使用一組與相應(yīng)的固定流率穩(wěn)態(tài)壓力,線性的測定就可以成立.線性正偏電壓模式用于測量Km=Q/FH,從而確定裂隙巖體滲透系數(shù),其中Q是流量下穩(wěn)態(tài)條件下,H是水頭,F(xiàn)是幾何形狀的因素。然后將探頭拉回一個(gè)短的距離,讓地面的貯藏器去進(jìn)行額外的測試來確定為新的L/D幾何尺寸.如果測試兩個(gè)或兩個(gè)以上的L/D比率,分別用縱向和橫向滲透系數(shù)Kv及Kh進(jìn)行測試,可以推導(dǎo)出測量的滲透率Km,即L/D比值,從而增加待定樣本大小對滲透性的影響。通常情況下,可以在一個(gè)小時(shí)內(nèi)測試的特定的L/D有四個(gè)穩(wěn)定狀態(tài)。MKII測試程序建立將由Ratnam等專家詳細(xì)介紹。沃斯、休斯和博爾頓、惠特爾對自傳式旁壓儀的描述??死恕⒁撂貭栠M(jìn)行的相關(guān)實(shí)驗(yàn)正在進(jìn)行討論。MKII試驗(yàn)大約每3米的間隔進(jìn)行一次測試,分別測試3米和12米之間時(shí)的數(shù)據(jù)。這些測試深度是類似的早期PERMAC法測試深度。SBP的軟土地基配置,切割機(jī)位于底部邊緣,被一起用于一個(gè)便攜式鉆井設(shè)置。這種儀器的直徑為0.083m。便攜式設(shè)置參數(shù)和設(shè)備的詳細(xì)情況在其他地方有所介紹。圖3所示為測試序列。一般情況下,壓縮測試首先進(jìn)行,然后鉆儀器MKII測試水平,其中的L=0水平(零長度腔)試驗(yàn)是首次進(jìn)行的。然后將儀器分階段拉回到創(chuàng)建短長度為L/D比1,2和4MKII的測試。這個(gè)序列通常在一天內(nèi)完成。第二天上午,鉆探儀器和相關(guān)實(shí)驗(yàn)在大約相同的深度L=0處進(jìn)行測試。相關(guān)支持的試驗(yàn)是在相同的深度大約為MKII測試水平提供的直接和間接的滲透性測量對比。壓縮和支持試驗(yàn)深度是底邊后方及空隙壓力盒和擴(kuò)大膜的中心0.5米處。持續(xù)的壓縮測試進(jìn)行遠(yuǎn)離MKII的測試影響的區(qū)域。進(jìn)行所有試驗(yàn)都是使用相同的儀器并且沒有完全收回從鉆孔儀器的需要的一個(gè)單一的自傳式操作。記錄的在鉆孔SBP3進(jìn)行的試驗(yàn)數(shù)據(jù)如圖四所示。軟粘土的存儲試驗(yàn)中我們關(guān)注的一個(gè)問題是,當(dāng)儀器收回中L/D>0時(shí)鉆孔將不會繼續(xù)打開。如果在僵硬高爾特粘土中進(jìn)行試驗(yàn)將不會出現(xiàn)這種問題。不排水穩(wěn)定計(jì)算,類似隧道導(dǎo)洞在軟土壤中,假設(shè)各向同性條件波斯肯納粘土,用于表示一個(gè)完全淹沒的井的安全性相當(dāng)高的因素,即:當(dāng)井滿水。這后來通過實(shí)地觀察得到驗(yàn)證。通常在L/D=2或4的無支撐的洞,經(jīng)過測試一夜之后,第二天早上才開始鉆取支持試驗(yàn)的深度。當(dāng)儀器傳到洞附近時(shí),沒有泥屑鉆水返回。只有超過L=0的水平才會遇到新鮮的材料,插桿進(jìn)行觀察。在這期間至少15的小時(shí)安全測試洞穴的完整性,因此符合。圖二巖土性質(zhì)和地質(zhì)狀況圖三Bothkennar粘土中的測試序列圖四鉆孔SBP3測試日志圖五樣品MKII從6米的深度鉆孔SBP3設(shè)置的數(shù)據(jù):(a)在6米的深度穩(wěn)定狀態(tài)壓力為L=d1(P3T5);(b)在6米的深度不同的線性關(guān)系MIKII測試結(jié)果雖然只有兩個(gè)流速(和相應(yīng)的穩(wěn)態(tài)孔隙壓力),需要定義每個(gè)L/D比的線性關(guān)系,如上所述,幾個(gè)流速試圖檢查L/D線性。例如,比值等于1時(shí),建立五個(gè)穩(wěn)態(tài)壓力(圖5(a))。還確定了各種L/D比率在每個(gè)測試的深度級別的線性關(guān)系。如圖5所示是一個(gè)典型的數(shù)據(jù)集。由于樣本量的增加,試驗(yàn)的其他特征如那些制作者描述的那樣(圖2)正越來越多地包含在測試區(qū)域。大部分這些功能,如裂變和沙紋層,往往作為樣本量的增加,并結(jié)合這些特點(diǎn),以提高測量的滲透率。反映在圖5(b)所示的線性關(guān)系的斜率逐漸平坦。請注意,逆坡用公式Km=Q/FH。測得的滲透率數(shù)據(jù)與橫向和縱向滲透,KH和KV系數(shù),使用的關(guān)系為使用這種關(guān)系和各向異性比Rk=Kh/Kv=2,從實(shí)驗(yàn)室研究決定,由其他人對數(shù)據(jù)進(jìn)一步解釋,以反映KH和KV,并與假設(shè)坐在從以前的調(diào)查數(shù)據(jù)的地點(diǎn)(圖6)??梢院芮逦目闯觯挥蠯h從L=D/2和4MKII的數(shù)據(jù)和KV從L/D=0到1MKII的數(shù)據(jù)分別顯示在圖6(a)和(b)。MKII的Kh數(shù)據(jù),如圖6(一)所示,比根據(jù)BAT和PERMAC公司數(shù)據(jù)繪制的數(shù)據(jù)的一般比測壓要高。作者同意洛爾萊等領(lǐng)頭所測的估計(jì)滲透率。有趣的是,要注意區(qū)別的L/D=2,L/D=4的數(shù)據(jù)是不太突出的PERMAC的MKII方法.與PERMAC所計(jì)算出的結(jié)果之間的差異較小,可以歸因于直徑較小的PERMAC設(shè)備(0'073米),當(dāng)儀器被收回并重新插入為L/D=4,或干脆到織物的變異發(fā)生涂抹。這是MKII和大直徑實(shí)驗(yàn)室實(shí)驗(yàn)室測試結(jié)果之間的公平競爭。圖六MKII的數(shù)據(jù)和其他數(shù)據(jù)的比較:(a)Kh;(b)Kv圖6(a)還顯示了在原始觀測和克拉克在一系列和鉆孔PR1測試數(shù)據(jù)有合理的共識,更早的數(shù)據(jù)來自克拉克的詮釋。以前的方法是不能夠獲得Kv的直接原位測量,不像MKII的方法可以從L=0開始測試以及在隨后的L/D比率變化進(jìn)行試驗(yàn).因MKII的Kv數(shù)據(jù)測試只能用實(shí)驗(yàn)室千伏數(shù)據(jù)(相比圖6(b))。合理的共識是通過觀察得知的,有很少Kv數(shù)據(jù)的變化,表明在垂直方向上,預(yù)計(jì)低影響較小的結(jié)構(gòu)。壓縮試驗(yàn)結(jié)果壓縮試驗(yàn)數(shù)據(jù)可使用博爾頓和惠特爾新的非線性排水腔擴(kuò)張彈性的解決方案進(jìn)行分

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