岩土工程锚杆中英文对照外文翻译文献

岩土工程锚杆中英文对照外文翻译文献岩土工程锚杆中英文对照外文翻译文献(文档含英文原文和中文翻译)Effectofgroutpropertiesonthepull-outloadcapacityoffullygroutedrockboltAbstractThispaperrepresentstheresultofaprojectconductedwithdevelopingasafe,practicalandeconomicalsupportsystemforengineeringworkings.Inrockengineering,untensioned,fullycement-groutedrockboltshavebeenusedformanyyears.However,thereisonlylimitedinformationabouttheactionandthepull-outloadcapacityofrockbolts,andtherelationshipbetweenbolt–groutorgrout–rockandtheinfluenceofthegroutpropertiesonthepull-outloadcapacityofarockbolt.Theeffectofgroutpropertiesontheultimateboltloadcapacityinapull-outtesthasbeeninvestigatedinordertoevaluatethesupporteffectofrockbolts.Approximately80laboratoryrockboltpull-outtestsinbasaltblockshavebeencarriedoutinordertoexplainanddeveloptherelationsbetweenthegroutingmaterialsanduntensioned,fullygroutedrockbolts.Theeffectsofthemechanicalpropertiesofgroutingmaterialsonthepull-outloadcapacityofafullygroutedbolthavebeenqualifiedandanumberofempiricalformulaehavebeendevelopedforthecalculatingofthepull-outloadcapacityofthefullycement-groutedboltsonthebasisoftheshearstrength,theuniaxialcompressivestrengthofthegroutingmaterial,theboltlength,theboltdiameter,thebondingareaandthecuringtimeofthegroutingmaterial.Keywords:Rockbolt;Groutingmaterials;Boltpull-outloadcapacity;Boltgeometry;Mortar1.IntroductionInrockengineering,rockboltshavebeenusedtostabiliseopeningsformanyyears.Therockboltingsystemmayimprovethecompetenceofdisturbedrockmassesbypreventingjointmovements,forcingtherockmasstosupportitself(Kaiseretal.,1992).Thesupporteffectofrockbolthasbeendiscussedbymanyresearchers(e.g.Hyettetal.,1992;Itoetal.,2001;Reichertetal.,1991andStillborg,1984).Rockboltbindstogetheralaminated,discontinued,fracturedandjointedrockmass.Rockboltingnotonlystrengthensorstabilizesajointedrockmass,butalsohasamarkedeffectontherockmassstiffness(Chappell,1989).Rockboltsperformtheirtaskbyoneoracombinationofseveralmechanisms.Boltsoftenacttoincreasethestressandthefrictionalstrengthacrossjoints,encouraginglooseblocksorthinlystratifiedbedstobindtogetherandactasacompositebeam(FranklinandDusseault,1989).Rockboltsreinforcerockthroughafrictioneffect,throughasuspensioneffect,oracombinationoftwo.Forthisreason,rockbolttechniqueisacceptableforstrengtheningofmineroadwayandtunnellinginalltypeofrock(PanekandMcCormick,1973).Generallyrockboltscanbeusedtoincreasethesupportoflowforcesduetothediameterandthestrengthoftheboltmaterials.Theyenablehighanchoringvelocitytobeusedatcloserspacingbetweenbolts.Theirdesignprovideseithermechanicalclampingorcementgroutingagainsttherock(AldorfandExner,1986).Anchoragesystemofrockboltisnormallymadeofsolidortubeformedsteelinstalleduntensionedortensionedintherockmass(Stillborg,1986).Rockboltscanbedividedintothreemaingroupsaccordingtotheiranchoragesystems(FranklinandDusseault,1989;AldorfandExner,1986;HoekandWood,1989;CybulskiandMazzoni,1989).Firstgroupisthemechanicallyanchoredrockboltsthatcanbedividedintotwogroups:slitandwedgetyperockbolt,expansionshellanchor.Theycanbefixedintheanchoringparteitherbyawedge-shapedclampingpartorbyathreadedclampingpart.Secondgroupisthefriction-anchoredrockboltsthatcanbesimplydividedintotwogroups:split-setandswellex.Friction-anchoredrockboltsstabilisetherockmassbyfrictionoftheoutercoveringofboltagainstthedrillholeside.Thelastgroupisthefullygroutedrockboltsthatcanalsobedividedintotwogroups:cement-groutedrockbolts,resingroutedrockbolts.Agroutedrockbolt(dowel)isafullygroutedrockboltwithoutmechanicalanchor,usuallyconsistingofaribbedreinforcingbar,installedinadrillholeandbondedtotherockoveritsfulllength(FranklinandDusseault,1989).Specialattentionshouldbepaidtocement-groutedboltsandboltsbonded(glued,resined)bysyntheticsresinsforboltadjustment.Groutedboltsfixtheusingofthecoherenceofthesealingcementwiththeboltrodandtherockforfasteningthebolts.Syntheticresin(resinedbolt)andcementmortar(reinforced-concretebolt)canbeusedforthistyperockbolt.Theseboltsmaybeanchoredinalltypeofrock.Anchoringrodsmaybemanufacturedofseveralmaterialssuchasribbedsteelrods,smoothsteelbars,cableboltsandotherspecialfinish(AldorfandExner,1986).Groutedboltsarewidelyusedinminingforthestabilisationoftunnelling,miningroadway,driftsandshaftsforthereinforcingofitsperipheries.Simplicityofinstallation,versatilityandrelativelylowcostofrebarsarefurtherbenefitsofgroutedboltsiscomparisontotheiralternativecounterparts(IndraratnaandKaiser,1990).Boltsareself-tensioningwhentherockstartstomoveanddilate.Theyshouldthereforebeinstalledassoonaspossibleafterexcavation,beforetherockhasstartedtodeform,andbeforeithaslostitsinterlockingandshearstrength.Althoughseveralgrouttypesareavailable,inmanyapplicationswheretherockhasameasureofshorttermstability,simplePortlandcement-groutedreinforcingdowelsaresufficient.Theycanbeinstalledbyfillingthedrillholewithlean,quicklysetmortarintowhichthebarisdriven.Thedowelisretainedinupholeseitherbyacheapformofendanchor,orbypackingthedrillholecollarwithcottonwaste,steelwool,orwoodenwedges(FranklinandDusseault,1989).Concretegroutedboltsusecementmortarasabondingmedium.Indrillholesatminimumof158belowthehorizontalplane,themortarcansimplypouredin,whereasinraisingdrillholesvariousdesignofboltsorotherequipmentisusedtopreventthepumpedmortarfromflowingout(AldorfandExner,1986).Theloadbearingcapacityoffullycement-groutedrockboltsdependsontheboltshape,theboltdiameter,theboltlength,rockandgroutstrength.Thebondstrengthoffullycement-groutedrockboltsisprimarilyfrictionalanddependsontheshearstrengthatthebolt–groutorgrout–rockinterface.Thusanychangesinthisinterfacesshearstrengthmustaffecttheboltbondstrengthandboltloadcapacity.Thislaboratorytestingprogramwasexecutedtoevaluatetheshearstrengtheffectonthebondstrengthofthebolt–groutinterfaceofathreadedbarandthelaboratorytestresultsconfirmthetheory.2.PrevioussolutionsTheeffectivenessofagroutedboltdependsonitslengthrelativetotheextentofthezoneofoverstressedrockoryieldzone.Theshearandaxialstressdistributionsofagroutedboltarealsorelatedtotheboltlengthbecauseequilibriummustbeachievedbetweentheboltandthesurroundingground(IndraratnaandKaiser,1990).Bearingcapacitiesofcement-groutedrockbolts(Pb)andtheiranchoringforcesareafunctionofthecohesionofthebondingagentandsurroundingrock,andtheboltingbar.Theultimatebearingcapacityofthebolt(Pm)isexpressedasfollows(AldorfandExner,1986): (1)wherekb,safetycoefficient(usuallykb=1.5);C1,cohesionofthebondingmaterialonboltingbar,ld,anchoredlengthofthebolt,ds,boltdiameter. (2)wheredv,drillholediameter；C2,cohesionofthebondingmaterialwithsurroundingrock(carboniferousrocksandpolyesterresinsC2=3MPa). (3)whereC3,shearingstrengthofthebondingmaterial.Themaximum(ultimate)bearingcapacityofthebolt(Pm)willbethelowestvaluefromP1toP111.Bearingcapacitiesofalltypeboltsmustalsobeevaluatedfromtheviewpointofthetensilestrengthoftheboltmaterial(Pms),whichmustnotbelowerthantheultimatebearingcapacityresultingfromtheanchoringforcesofboltsindrillholes(Pm).Itholdsthat(4)wherePms,theultimatebearingcapacityoftheboltwithrespectofthetensilestrengthoftheboltmaterial;Pm,theultimatebearingcapacityofthebolt.3.Laboratorystudy3.1.ExperimentsThepull-outtestswereconductedonrebars,groutedintobasaltblockswithcementmortarinlaboratory.Therelationsbetweenboltdiameter(db)andpull-outloadofbolt(Pb)(Fig.2),boltarea(Ab)andpull-outloadofbolt(Pb)(Fig.3),boltlength(Lb)andpull-outloadofbolt(Pb)(Fig.5),watertocementratio(w/c)andboltbondstrength(τb)(Fig.7),mechanicalpropertiesofgroutmaterialandboltbondstrength(τb)(Fig.9,Figs.10and11),andcuringtime(days)andboltstrength(Figs.12and13)wereevaluatedbysimplepull-outtestprogramme.Thesamplesconsistedofrebars(ranging10–18mmdiameterstwobytwo)bondedintothebasaltblocks.ThesebasaltblocksusedhaveaYoung’smodulusof27.6GPaandauniaxialcompressivestrength(UCSg)of133MPa.Drillingholeswhichwere10mmlargerthantheboltdiameter,havingadiameterof20–28mmforinstallationofbolts,weredrilledupto15–32cmindepth.Theboltwasgroutedwithcementmortar.ThegroutwasamixtureofPortlandcementwithawatertocementratioof0.34,0.36,0.38and0.40curedfor28days.Inordertoobtaindifferentgrouttypesthathavedifferentmechanicalproperties,siliceoussand<100μm;500μm>andflyash<10μm;200μm>wereaddedinaproportionof10%ofcementweightandwhitecementwithawatertocementratioof0.40.Thesandshouldbewellgraded,withamaximumgrainsizeofv2mm(Schacketal.,1979).TheYoung’smodulusofthegroutswasmeasuredduringunconfinedcompressiontestsandshearstrengthwascalculatedbymeansofringsheartests.Thetestset-upisillustratedschematicallyinFig.1andtheprocedureisexplainedbelow:1.Afterfillingpreparedgroutmortarintothehole,boltisinsertedtothecentreofdrillinghole.2.Aftercuringtime,therebarsintherockwereaxiallyloadedandtheloadwasgraduallyincreaseduntiltheboltfailed.3.Thebondstrength(τb)wasthencalculatedbydividingtheload(Pb)bysurfacearea(Ab)oftheboltbarincontactwiththegrout.4.Pull-outtestswererepeatedforvariousgrouttypes,boltdimensionsandcuringtimes.Theinfluenceoftheboltdiameterandthebondareaonthebondstrengthofarockboltcanbeformulatedasfollows(LittlejohnandBruce,1975):(5)whereτb,ultimateboltbondstrength(MPa);Pb,maximumpull-outloadofbolt(kN);db,boltdiameter(mm);lb,boltlength(cm);πdblb,bondedarea(cm2).3.2.Analysisoflaboratorytestresults3.2.1.Infl uenceoftheboltmaterialBoltdiametersof10,12,14,16and18mmwereusedinpull-outtests.TypicalresultsarerepresentedinTable1,Figs.2and3.Themostimportantobservationswere: (1)Themaximumpull-outload(Pb)increaseslinearlywiththesectionoftheboltwhileembedmentlengthwasconstant.(2)Boltsectiondependsuponboltdiameter.Therelationbetweenboltdiameterandboltbearingcapacitycanbeexplainedasfollowempiricformulae(Fig.2).(6)(3)Thevaluesofboltbondstrengthwerecalculatedbetween5.68and5.96MPa(Table1).Boltlengthsof15.0,24.7,27.0,30.0and32.0cmwereusedinpull-outtestsasseeninFig.4.TypicalresultsarerepresentedinTable2,andFigs.5and6.Themostimportantobservationswere:(1)Thepull-outforceofaboltincreaseslinearlywiththeembeddedlengthofthebolt.(7)(2)Maximumpull-outstrengthofaboltislimitedtotheultimatestrengthoftheboltshank.3.2.2.InfluenceofgroutingmaterialThewatertocementratioshouldbenogreaterthan0.40byweight;toomuchwatergreatlyreducesthelong-termstrength.Because,partofthemixingwaterisconsumedbythehydrationofcementused.Restofthemixingwaterevaporatesandthencapillaryporositiesexistwhichresultsinunhomogenitiesinternalstructureofmortar.Thus,thisstructurereducesthelong-termstrengthbyirregularstressdistribution(Neville,1963;Atis,1997).Toobtainaplasticgrout,bentonitclaycanbeaddedinaproportionofupto2%ofthecementweight.Otheradditivescanacceleratethesetting-time,improvethegroutfluidityallowinginjectionatlowerwatertocementratios,andmakethegroutexpandandpressurizethedrillhole.Additives,ifusedatall,shouldbeusedwithcautionandinthecorrectquantitiestoavoidharmfulsideeffectsuchasweakeningandcorrosion(FranklinandDusseault,1989).Thewatertocementratio(w/c)ingroutingmaterialsconsiderablyaffectspull-outstrengthofbolt.AsseeninTable3,UCSgandshearstrength(tg)ofgroutinhighw/cratioshowlowervalueswhereasinloww/cratiohighervalues.Theratiobetween0.34and0.40presentsquitegoodresults.Althoughthew/cratioof0.34givesthebestbondstrength,groutibility(pumpability)decreasesandanumberofdifficultiesinapplicationappear.Inhighw/cratio,thepumpabilityofgroutingmaterialsintothedrillingholeiseasybutthebondstrengthofboltdecreases(Figs.7and8).Thebondstrengthoffullycement-groutedrockboltsisprimarilyfrictionalanddependsontheshearstrengthatthebolt–groutorgrout–rockinterface.Thusanychangeinthisshearstrengthofinterfacesaffectstheboltbondstrengthandloadcapacity.Theinfluencesofmechanicalpropertiesofgroutingmaterialsonthebearingcapacityofboltcanbedescribedasfollows:(1)Theuniaxialcompressiveandshearstrengthofthegroutingmaterialshasanimportantroleonthebehaviourofrockbolts.ItwasobservedthatincreasingshearstrengthofthegroutingmateriallogarithmicallyincreasesboltbondstrengthasshowninTable4andFig.9.Therelationbetweengroutshearstrengthandboltbondstrengthwasformulatedasfollows:(8)(2)Table4andFig.10showthatincreasinggroutcompressivestrengthconsiderableincreasesthebondstrengthofthegroutedbolts.(9)(3)InFig.11andTable4showthatthereisanotherrelationshipbetweenYoung’smodulusofgroutandboltbondstrength.IncreasingtheYoung’smodulusincreasesboltbondstrength.(10)3.2.3.InfluenceofthecuringtimeAnimportantproblemintheapplicationofcementgroutedboltsisthesettingtimeofthemortar,whichstronglyaffectsthestabilizingabilityofbolt.Cementgrouteddowelscannotbeusedforimmediatesupportbecauseofthetimeneededforthecementtosetandharden(FranklinandDusseault,1989).Inthepull-outtests,eightgroupofboltshavingsamelengthandmortarwithawatertocementratioof0.4wereusedfordeterminingtheeffectsofcuringtimeontheboltbondstrength.Eachgroupofrockbolttestingwasperformedafterdifferentsettingtimes(Table5).AscanbeseeninFigs.12and13,thestrengthofboltbondincreasesrapidlyin7daysduetocuringtime.However,thebondstrengthofboltcontinuestoincreaseratherslowlyafter7days.Rockboltsmaylosetheirsupportingabilitybecauseofyieldingofboltmaterial,failureatthebolt–groutorgrout–rockinterface,andunravellingofrockbetweenbolts.However,laboratorytestsandfieldobservationssuggestthatthemostdominantfailuremodeisshearatthebolt–groutinterface(HoekandWood,1989).So,thislaboratorystudyfocussedontheinterfacebetweenrockboltandrockandthemechanicalpropertiesofgroutingmaterials.4.ConclusionsThelaboratoryinvestigationshowedthattheboltcapacitydependsbasicallyonthemechanicalpropertiesofgroutingmaterialswhichcanbechangedbywatertocementratio,mixingtime,additives,andcuringtime.Increasingtheboltdiameterandlengthincreasestheboltbearingcapacity.However,thisincreaseislimitedtotheultimatetensilestrengthoftheboltmaterials.Mechanicalpropertiesofgroutingmaterialshaveanimportantroleontheboltbearingcapacity.Itisofferedthattheoptimumwatertocementratiomustbe0.34~0.4andthemortarhavetobewellmixedbeforepouredintodrillhole.Improvingthemechanicalpropertiesofthegroutingmaterialincreasestheboltbearingcapacitylogarithmically.Thebestrelationshipwasobservedbetweengroutshearstrengthandboltbondstrength.Increasingthecuringtimeincreasestheboltbondstrength.Boltbondstrengthof19kg/cm2infirstday,77kg/cm2in7daysand86kg/cm2in35dayswasdeterminedrespectively.Theresultsshowthatboltbondstrengthincreasesquicklyinfirst7daysandthentheincreasegoesupslowly.Bondfailureinthepull-outtestoccurredbetweentheboltandcementgrout,ofwhichthemechanicalbehaviourisobservedbyshearspring.Thisexplainsthedevelopmentofboltbondstrengthandthefailureatthebolt–groutinterfaceconsideringthatthebondstrengthiscreatedasaresultofshearstrengthbetweenboltandgrout.Thismeansthatanychangeatthegroutstrengthcausestothechangingofboltcapacity.Thefailuremechanisminapull-outtestwasstudiedinordertoclarifythebondeffectofrockbolt.Thusonemainbondeffectwasexplainedfrombondstrengthofrockbolts.

中文翻译水泥浆性能对充分注浆锚杆拉拔承载力的影响A.Kılıc,E.Yasar*,A.G.Celik摘要：本文代表了一项在安全、实用、经济的支持系统指导下的工程结果。在岩石工程中，没有被拉紧的且被水泥充分注浆的锚杆已使用多年。然而，对锚杆的作用过程和其拉拔载荷的能力，以及锚杆注浆或注浆的关系，水泥性能对充分注浆锚杆拉拔承载力的影响研究却很少。为了评估锚杆支护效果，我们开始对水泥性能对最终锚杆在拉拔试验载荷能力的影响进行了研究。大约80个针对玄武岩块的锚杆拉拔试验实验室已开始进行研究以用来解释和发展注浆材料和松弛的充分注浆锚杆之间的联系。这种注浆材料的力学性能对一个完全锚杆拉拔承载力的力学性能的影响已被数量化，而且，为了计算充分注浆锚杆的承载能力，在考虑剪切强度，注浆材料的单轴抗压强度，锚杆长度，锚杆直径，粘结面积及注浆材料固化时间的基础上，一些经验公式已被提出和不断的发展。关键词：锚杆；注浆材料；锚杆拉拔承载能力；锚杆几何形状；砂浆1引言在岩土工程中，锚杆已多年被用来稳定开口。该锚杆支护系统可通过阻止接缝处移动，迫使岩块支持其本身来提高岩体抗扰动能力(Kaiseretal.,1992)。对这样的岩锚支护效果已被许多研究者讨论过(e.g.Hyettetal.,1992;Itoetal.,2001;Reichertetal.,1991andStillborg,1984)。岩锚和承受层压的，不连续的，有裂隙和节理的岩体结合在一起。锚杆支护不仅加强或稳定节理岩体，同时也对岩体刚度有着显着的影响(Chappell,1989)。锚杆的支护效果一个或几个机制相结合来实现的。锚杆通常作为一个组合梁来增加应力和节理处的摩擦强度，固定松散岩块或分层岩床(FranklinandDusseault,1989)。锚杆加固岩石是通过岩石间的摩擦作用，悬吊形态，或摩擦作用和悬吊两者兼有而实现的。基于这个原因，锚杆技术在支护巷道方面的应用可以适用所有岩石类型的(PanekandMcCormick,1973)。一般来说锚杆可用于增加由于直径低势力的支持和锚杆材料的强度。它们使高速贴壁将在更紧密的锚杆间距使用。他们的设计可以用来机械夹紧或对岩石进行水泥注浆(AldorfandExner,1986)。锚杆锚固系统通常是指固体或管状型钢安装在松散或坚实岩体中(Stillborg，1986年)。按照其锚固系统，锚杆可分为三个主要类型(FranklinandDusseault,1989;AldorfandExner,1986;HoekandWood,1989;CybulskiandMazzoni,1989)。第一类是机械岩锚，它可以分为两类：楔缝式锚杆，外壳膨胀锚杆。它们被安装在锚杆上的一部分，具体是在楔形夹紧的锚杆螺纹部分或者是夹紧部分。第二类是摩擦岩锚，它可以简单地分为两类：分节锚杆和膨胀锚杆分为锚杆。摩擦锚杆锚固岩体是由外露锚杆和钻孔的摩擦力完成的。最后一类是充分注浆锚杆，它也可分为两小类：水泥注浆锚杆，树脂锚杆。注浆锚杆(桩)是一种无机械锚定，通常包括一个带肋钢筋，该钢筋被安装在一个钻孔里面并和超过其全长的岩体结合(FranklinandDusseault,1989)。特别要注意的是水泥注浆锚杆和螺栓(胶合，树脂)是根据合成树脂锚杆适当调整固定的。锚固螺栓要与连杆螺栓和水泥的密封粘结以及用来拴紧螺栓的岩体相适应。合成树脂(树脂锚杆)和水泥砂浆(钢筋混凝土锚杆)可以为这种类型的锚杆使用。这些锚定锚杆可以被固定在所有类型岩石中。锚定杆体可以用多种材料制造，如带肋钢筋，光面钢筋，锚索和其他特殊处理的材料(AldorfandExner,1986)。注浆锚杆广泛应用于矿井中的掘进，巷道，平巷和井筒的支护和加强其外围的稳定性。与其它替代品相比较，注浆锚杆安装的简单性，多功能性和相对低成本性则会取得更多的效益(IndraratnaandKaiser,1990)。当岩石开始移动和扩张时，锚杆会自动拉紧。因此，在开凿巷道后，岩体开始变形和已经失去联动性和剪切强度之前要尽快安装这些锚杆。虽然只有几种水泥浆类型可以适用，但是在现场许多应用中这些类型水泥浆已经足够，例如在被测得有短暂稳定期，用简单的波特兰水泥注浆加固销钉措施的岩体中应用。通过倾斜着向钻孔里面快速注满灰泥浆，它们可以被安装在已经拉紧的杆体中。保留的销子最终以简单的形式形成了锚孔，或用棉花包装废弃物，钢丝绒，或木楔子(FranklinandDusseault,1989)。混凝土锚杆是用水泥砂浆作为粘结介质。在最低低于水平面158的钻孔里面，砂浆很容易注入，然而在逐渐升高钻洞中，各种锚杆或其他设备的设计则会用来防止水泥砂浆流出的(AldorfandExner,1986)。充分水泥注浆锚杆承载能力取决于锚杆直径，锚杆长度，岩石和水泥浆的强度。这种充分注浆锚杆的锚固强度最初是靠摩擦力的，因此是取决于锚杆和水泥，水泥和岩体两个层面的剪切强度。因此，在这个界面的剪切强度的任何变化都将影响锚杆的锚固力和其承载能力。实施实验室的测试方案的目的是评估在水泥注浆锚杆和锚杆界面上剪切强度的变化对锚固力的影响，并且该实验测试结果证实了这一理论。2解决方案相对于过分受压区或屈服区的岩体来说，一个锚杆的有效性取决于其长度。一个锚杆剪切应力和轴向应力的分布，也关系到有效锚杆长度，因为应力平衡必须由锚杆和围岩共同实现的(IndraratnaandKaiser,1990)。水泥注浆锚杆(Pb)的承载能力，锚固力是其粘结剂的凝聚力，围岩和锚杆杆体的函数。从而得到最终的锚杆(Pm)承载能力公式，表示如下(AldorfandExner,1986)：(1)式中kb是安全系数(通常取1.5)；C1作用在锚杆上的粘结材料的粘结力；ld，锚杆长度；ds锚杆直径。(2)式中dv，钻孔直径，C2,粘合材料与围岩之间的凝聚力(C2=3MPa)(3)式中C3为粘结材料的剪切强度。螺栓的最大承载能力将是从P1到P111的最低值所有类型的锚杆承载能力都必须从锚杆材料的拉伸强度(Pms)的角度进行评估，且由于锚杆在钻孔中的锚固力，这种拉伸强度必须不得超过极限承载力。它认为：(4)式中Pms,考虑到锚杆材料抗拉强度时的极限承载能力；Pm，锚杆的极限承载能力。3实验室研究3.1实验拉拔试验是在实验室被水泥砂浆玄武岩块注浆的钢筋进行的。通过简单的拉拔试验方案我们评估了锚杆直径(db)和锚杆拉应力(以Pb计)(图2)，锚杆面积(Ab)和锚杆拉应力(Pb)(图3)，锚杆长度(Lb)和锚杆拉应力(Pb)(图5)，水灰比(w/c)和锚杆粘结强度(τb)(图7)，注浆材料的机械性能和锚杆粘结强度(τb)(图9，图10和11)，固化时间(天)和锚杆强度(图12和13)之间的关系。这些样本包括了和玄武岩岩块固结在一起的钢筋(成对的直径在10-18mm)。所用的这些玄武岩块的杨氏模量是27.6GPa和单轴抗压强度133兆帕(UCSg)。钻孔的深度是15-32cm，并要求钻孔的直径是20-28cm，比锚杆直径大10mm。锚杆被水泥砂浆注浆。该水泥浆是各种不同水灰比的硅酸盐水泥混合组成的，不同的水灰比有0.34,0.36,0.38和0.40，凝结时间为28天。为了获得具有不同的力学性能不同类型的水泥浆，将<500μm，>100μm的硅质砂；粉煤灰>10μm，<200μm加入到水泥重量占10%，水灰比为0.40的白水泥浆中。沙粒应很好的分级，最大晶粒尺寸为2毫米(施克等人，1979)。杨氏模量的测量是在无限压缩试验中进行，同时抗剪强度是由环刀试验方法计算。该试验的图解说明如图1。程序说明如下：(1)在将水泥砂浆注入钻孔之后，锚杆被插入到钻孔中心。(2)过了凝结时间后，在岩体中的钢筋承受轴向载荷，逐渐加大载荷直到锚杆被拉断(3)负载(Pb)除以注浆锚杆接触表面积(Ab)计算得到粘结强度(tb)。(4)以不同类型的水泥浆，锚杆尺寸和固化时间重复拉拔试验。锚杆直径和粘结面积对锚杆粘结强度的影响可以公式化，公式如下(利特尔约翰和Bruce，1975)：(5)式中，τb为锚杆极限承载力(MPa)；Pb为锚杆承受的最大载荷(kN)；lb锚杆长度(cm