(6.2.16)-Cast-in-place Pile工程图纸与工程规范

ConstructionofFoundationandFoundationWorkConstructionofFoundationandFoundationWorkCast-in-placePileConstructionTask1Adamancyisastrongbranchwhichcankeepthetreestandinguprightinthewind;adamancyisthestandingsail,whichcanmaketheboatgoaheadthroughthewaves;adamancyisasolidfoundation,whichcankeepthebuildingstandingforahundredyears.Incaseofweaksoillayer,lowbearingcapacityofshallowsoilontheconstructionsite,high-risebuildings,industrialbuildingswithlargeupperloadorsomespecialbuildingswithstrictrequirementsfordeformationandstabilityduringtheconstructionoftheproject,whentheshallowfoundationisnotpossible,itisnecessarytoconsideradoptingfoundationtreatmentmeasures,orconsiderusingthesolidsoillayerorrockstratumdeepinthefoundationasthebearinglayerandchoosethedeepfoundationscheme.01TaskRequirementsConstructionofFoundationandFoundationWorkTaskRequirementsTheprojectisanindustrialplantproject.Thepilefoundationisdesignedasarotaryexcavationcast-in-placepile.Thedesignedpilediameteris1,000~2,000mmandthedesignedpilelengthis≥4,000mm.Thepileendenteringthebearinglayeris≥500mm.TheconcretegradeofthepileshaftisC30.Thepouringshallbe800mmhigherthantheeffectivepiletopelevation,andshallbechiseledbeforetheconstructionofthebearingplatform.Seetable4-2-1listofpilefoundationsforpilebodydimensions,andseefigure4-2-1foundationlayoutplanforpiletopelevationandpilelength.PileNo.PileShaftDiameterD(Mm)Rock-socketedDepthhr(Mm)PileShaftLengthH(M)PileShaftReinforcementAs(Mm)RemarksZJ11000500Accordingtothereality1612C30concretecorefillingZJ21200500Accordingtothereality1812ZJ31500500Accordingtothereality2016Table4-2-1PilefoundationscheduleTaskRequirementsFigure4-2-1FoundationlayoutplanTaskRequirementsPreparetheconstructionschemeofrotaryexcavationcast-in-placepileaccordingtotheactualworksituationTimeRequirementsTeachinghours:10classhoursBasisofPreparationAccordingtothecontentsandcharacteristicsoftheprojectandincombinationwiththespecificconditionsoftheproject,listthecurrenteffectivespecificationsandstandardsConstructionMethodsTheconstructionmethodshallbepreparedinstrictaccordancewithtechnicalrequirementsfortheconstructionofrotaryexcavationcast-in-placepiles.Thecost-efficientandappropriateconstructionmethodsshallbeselectedfirst,andconstructionmethods,constructionprocess,keypointsofconstructiontechnologyandconstructionqualitycontrolrequirementsforrotaryexcavationcast-in-placepilesshallbespecified.SafetyandQualityMeasuresItshallbepreparedinstrictaccordancewithconstructionqualitycontrolrequirementsforrotaryexcavationcast-in-placepiletoensureconstructionsafety.EnvironmentalQualityMeasuresItshallbepreparedinstrictaccordancewithenvironmentalprotectionrequirementsforrotaryexcavationcast-in-placepileconstruction.TaskRequirements02KnowledgeNavigationConstructionofFoundationandFoundationWorkKnowledgeNavigationFunctionandClassificationICast-in-placepileisapileformedbydirectlyformingaholeinthepilepositionandthenplacingareinforcementcagetopourconcrete.Comparedwithprecastpiles,cast-in-placepilesavoidtheharmfulimpactofpilingonadjacentbuildings,andhavetheadvantagesofsavingmaterials,lowcost,constructionisnotlimitedbystratumchanges,andthereisnoneedtoconnectorcutpiles.Thus,itiswidelyusedandhasthetrendtoreplaceprecastpiles.However,strictrequirementsshallbemetduringoperationanditislikelytocausequalityaccidentsduetoslightnegligence.Acertainmaintenanceperiodisrequiredafterconstruction,soitisimpossibletobeartheloadimmediately.Itisdifficulttoconstructinwinter.Generally,accordingtodifferentconstructionmethods,cast-in-placepilescanbedividedintoboredcast-in-placepiles,immersedcast-in-placepiles,explosionexpandedcast-in-placepiles,andmanuallydugcast-in-placepiles,asshowninFigure4-2-2.Cast-in-placePileWithsustainedandrapidgrowthofnationaleconomysince1980s,China'sconstructionhaswitnessedanunprecedentedperiodofusingpilesinalargescale.Itisestimatedthatoverthepast10years,Chinahasusedmorethan50millionpileseveryyear,rankingfirstintheworld.Therearemorethantenthousandhigh-riseandsuperhigh-risebuildingssupportedonpilefoundations,andhundredsofbridgesandsuperlargebridgesacrosstheYangtzeRiver,theYellowRiver,thePearlRiver,theHuangpuRiver,theQiantangRiverandotherrivers.Atthebeginningofthe21stcentury,theDonghaiBridgeinShanghaiandtheHangzhouBayBridgeinZhejiangwerebothseacrossingbridgesbuiltonpilefoundations,andtheirscaleandlengtharealsoleadingintheworld.KnowledgeNavigationCast-in-situPoredPileIICast-in-situporedpileisakindofcast-in-situpileconstructedbydrillingfirstandthenformingpilesbyusingdrillingequipment.Becauseofitsexcellentadaptability,simpleconstructionoperationandlowequipmentinvestment,itiswidelyusedintheconstructionofindustrialbuildings,high-risebuildings,waterconservancyandhydropower,bridgesandwharfs.Accordingtodifferentsiteconditions,boredcast-in-placepilescanbedividedintodryboredcast-in-placepilesandslurryretainingwall(wet)boredcast-in-placepiles.KnowledgeNavigationCast-in-situPoredPileIICast-in-situporedpileisthemostcommonlyusedmainpiletypeinpilefoundationengineering.Itissuitableforvariousstratumconditions,withoutsoilsqueezingandnoise,andhaslittleimpactontheenvironmentinurbancentersandareaswithdensebuildings,Thereisnogreatdifficultyintheconstructionofultradeepandultralongpilefoundations.Therefore,thistypeofpileiswidelyusedalloverthecountry.KnowledgeNavigationIfyouwanttobuildahouse,youshouldfirstlayagoodfoundation,tampandlevelthefoundation,andbuildwallsandbeamsonit.Thehousesbuiltinthiswaywillbefirmanddurable.DryBoredCast-in-placePile（I）DryBoredCast-in-placePileDryboredcast-in-placepileisapileformedbydrillingwithdrillingequipment,cleaningtheholeimmediatelyaftertheholedepthmeetsthedesignrequirements,placingthereinforcementcage,andthenpouringconcreteunderwater,asshowninfigure4-2-3.Itiswellapplicabletothenortharea

andthesituationthatthegroundwaterlevelislowandthereisnogroundwaterwithintheholeformingdepth.Theconstructionequipmentissimplerandcheaperthantheboredcast-in-placepilewithslurrywallprotection.Becausethiskindofcast-in-placepileisconstructedinthedrysoillayerabovethegroundwaterlevel,itiscalleddryoperationcast-in-placepile.(a)Drillingwithdrillingrig;(b)Puttinginthereinforcementframework;(c)ConcretepouringSpecificationsandStandardsUnifiedStandardforConstructionQualityAcceptanceofBuildingEngineeringGB50300TechnicalSpecificationsforBuildingPileFoundation（JGJ94-2008）TechnicalSpecificationsforTestingofBuildingFoundationPiles(JGJ106-2003)SpecificationsandStandardsDryBoredCast-in-placePile1.ConstructionPreparationGenerally,spiraldrillingmachineisusedforholeforming.Itusesthepowertorotatethedrillpipe,cutsthesoildownward,andcausesthecutsoiltoriseandflowoutoftheholealongthewholedrillpipethroughthespiralblade.Theporediameterisgenerally300~600mm,upto800mmatmost,andthedrillingdepthis8~20m.Commonlyuseddrillingmachinesinclude:fullbladescrewdrills(asshowninFigure4-2-4),drillexpanders,fullcasingdrills,etc.Figure4-2-4Fullbladeaugermachine2.TechnologicalProcessPiledriverinplace→drillingsoiltoformahole→measuringtheholediameter,holedepthandthehorizontalandverticaldistanceofthepileholes,andcorrecting→diggingtothedesignelevation→holeformingqualityinspection→placingthereinforcementcage→placingtheholeopeningprotectionandfunnel→pouringconcreteandvibrating→pullingouttheholeprotection,funnelandholeforming.DryBoredCast-in-placePile3.KeyPointsofConstruction(1)PiledriverinplaceWhenthepiledriverisinplace,itmustbestablewithoutinclinationordisplacement.Inordertoaccuratelycontrolthedrillingdepth,acontrolrulershallbemadeontherackorthemachinepipeforobservationandrecordingduringconstruction.（2）DrillingsoiltoformholesStraightentheframetappet,alignthepileposition(withalignmentring),startthemachinetodrillandexcavate,andstopandliftdrillingafterreachingthecontroldepth.（3）QualityinspectionofporeformingUsesoundingrope(hammer)orportablelamptomeasureholedepthandvirtualsoilthickness.Thethicknessofvirtualsoilisequaltothedifferenceofdrillingdepth.Generally,thethicknessofemptysoilshallnotexceed10cm.Whendrillinginthesoillayerwithmorestonesorthesoftplasticclaylayerwithlargerwatercontent,itisnecessarytopreventtheholediameterfromexpandingduetotheshakingofthedrillpipe,resultingintheattachmentofdisturbedsoiltotheholewallandtheincreaseoffallingsoilatthebottomofthehole.DryBoredCast-in-placePile（4）PlacethereinforcementcageBeforeplacingthereinforcementcage,themortarcushionblockorplasticcardshallbebound;Whenthereinforcementcageishoistedandplaced,itshallbealignedwiththeholeposition,hoistedverticallyandstably,andsinkslowlytoavoidcollidingwiththeholewall.Thereinforcementcageshallbefixedimmediatelywhenitisplacedinthedesignposition.Whentwosectionsofreinforcementcageareconnected,weldingshallbeadoptedtoensurethatthepositionofreinforcementiscorrectandthelayerthicknessmeetstherequirements.（5)PourconcreteTheconcretepouringshallbecarriedoutcontinuously,vibratedandcompactedinlayers,andthelayerheightshallbedeterminedbythetampingtool,generallynotmorethan1.5m.Whentheconcreteispouredtothepiletop,itshallproperlyexceedthedesignelevationofthepiletoptoensurethattheelevationofthepiletopmeetsthedesignrequirementsafterthelaitanceischiseledout.Whentheconcreteispouredto1.5mfromthepiletop,thechutecanbepulledoutfordirectpouringandinserting.3.KeyPointsofConstructionDryBoredCast-in-placePile4.TheQualityControl(1)Beforeconstruction,therawmaterialsandconstructionsequenceformulatedintheconstructionorganizationdesign,performanceindicatorsofmainhole-formingequipment,monitoringinstruments,monitoringmethods,measurestoensurepersonnelsafetyorspecialsafetyconstructionschemesshallbeinspectedandaccepted.(2)Duringconstruction,thequalityofreinforcementcage,concreteslump,pileposition,holedepthandpiletopelevationshallbeinspected.(3)Aftertheconstruction,thebearingcapacityofthepile,theintegrityofthepilebodyandthestrengthoftheconcreteshallbeinspected.(4)Thequalityinspectionstandardfordryboredcast-in-placepilesshallcomplywiththeprovisionsofthequalityinspectionstandardfordryboredcast-in-placepilesintheAcceptanceStandardforConstructionQualityofBuildingFoundationEngineeringGB50202-2018,asshownintable4-2-3.DryBoredCast-in-placePile4.TheQualityControlTable4-2-3Qualityinspectionstandardfordryboredcast-in-placepileDryBoredCast-in-placePileable4-2-4Allowabledeviationofpilediameter,verticalityandpilepositionofcast-in-placepile4.TheQualityControlDryBoredCast-in-placePile5.QualityCommonDiseaseandPreventionMeasuresTable4-2-5Commonqualityproblems,causeanalysisandsolutionsofdryboredcast-in-placepileCommonQualityProblemsCauseAnalysisSolutionsTooMuchLooseSoilattheHoleBottomThevirtualearthwasnotcleanedintimeduringtheoperation.Thevirtualearthcontainsalargeamountofsandorsandypebbles.1.Virtualearthshallbecleanedintimeduringtheoperation.2.Twoormoretimesofdrillingandsoilremovalcanbeconductedwhennecessary.Thatis,usethedrilltoreachthedesignedelevationatonetime,rotateitattheoriginalpositionforamoment,andstoprotatingthestaticpullingdrillpipe.3.Ifthevirtualearthissandorsandypebble,theholebottomslurrycanbeusedformixingfirst,andthentheconcretecanbepoured.4.Theholebottompressuregroutingmethodandholebottomcompactionmethodshallbeadopted.DeformationofReinforcementCageThereinforcementcageisdeformedduetoimproperoperationintheprocessofstacking,transportation,lifting,holeentering,etc.Thereinforcementcagesshallbestacked,transported,hoistedanddrilledinstrictaccordancewiththeoperatingregulations.Thetechnicaldisclosuretotheoperatorsmustbestrengthened,andthereinforcementqualitymeasuresmustbestrictlyimplemented.ExcessivePileCuttingandFillingPiletopelevationcontrolisnotinplace,resultinginoverpouringorunderpouring.Whentheconcreteispouredclosetothepiletop,thetopelevationshallbemeasuredatanytimetoavoidexcessivepilecuttingandpilefilling.PoorQualityofPileConcreteTherearehoneycombsandholesintheconcreteofthepilebody,thepilebodyismixedwithsoil,andthegradingofsectionsisuneven.1.Ifthebearingcapacityofasinglepileisnotlargeandthedefectsarenotserious,themethodofenlargingthecappingbeamcanbeadopted.2.Ifthedefectsareserious,thetreatmentmethodshallbestudiedtogetherwiththedesigners.Generally,themethodoffillingpilesonbothsidesoftheaxiscanbeadopted.DryBoredCast-in-placePile1.Beforeconstruction,specialsafetydisclosureshallbecarriedoutfortheconstructionpersonnel,safetyandenvironmentalprotectiontrainingandassessmentshallbecarriedouttoenhancesafetyandenvironmentalprotectionawareness;Personnelforspecialtypesofworkmustbeemployedwithcertificates.2.Alloperatorsshalloperateinstrictaccordancewiththespecifications,andspecialpersonnelshallbeassignedtodirecttheconstructiononsite.Safetyprotectionshallbeimplementedattheconstructionsite.Non-constructionpersonnelarenotallowedtoentertheprotectiveline.Constructionpersonnelmustwearsafetyhelmetswhenenteringthesite.3.On-siteelectricalequipmentshallbeprovidedwithleakageprotectiondevice,andalldistributionwiresshallbethree-phase-five-wiresystem.Theelectricalsystemshallbeinthechargeofaspeciallyassignedpersonandequippedwithelectricalprotectiondevicesforinspectionatanytime.4.Theequipmentshallbemaintainedregularlyandoperatedbyfull-timepersonnelaccordingtotheoperatingprocedures.Hand-heldelectrictoolsshallbeprovidedwithneutralgroundingandleakageprotection,andinsulatedshoesandglovesshallbeworn.5.Thetransportvehiclesmustbeingoodcondition,noillegaldrivingisallowed,andthedriversshalldrivewithlicenses.Fornightoperation,theconstructionsiteshallbeprovidedwithsufficientlightingequipment.6.Themudandmuckinthesedimentationtankshallbecleanedandtransportedtotheappointedspoilgroundintime.Afterthepileiscompleted,themudandfloatingmuckaroundthepileshallbecleanedintimeforcentralizedtreatmenttoavoidpollutiontothesurfaceandsurroundingenvironment.SafetyControFirmlyEstablishSafetyAwarenessConstructionPlanProtectiontoFinishedProducts1.Thefabricationaccuracyofreinforcementcageanddeformationprotectionduringtransportationandhoistingshallbestrictlycontrolled.Duringhoisting,reinforcingtool-typerodshallbeusedforone-timeoverallhoistingandplacement.2.Whenthedrillingrigstartstopulloutthepilecasing,itshallpulloutthepilecasingslowlyandstatically,andthenreducetherotationangleofthepilecasingdriver,slowdowntherotationspeed,andpulloutinacombinationofclockwiseandcounterclockwisedirections.3.Addastiffeninghoopinthepositionofthefirststiffeninghoopofthereinforcementcage.4.Afterthepilecasinglooses,slowstaticpulling(norotation)shallbeadopted.5.Afterthepilecasingispulledout,theorificeshallbeprotectedwithsteelmesh,andtheemptyholeshallbebackfilledafter5h.6.Whenpouringconcrete,thetremieshallberemovedfrequentlytomaketheupwardforceofconcretelarger.7.Afterthepilecasingispulledout,thepileheadshallbevibrated.8.Adjusttheconcretemixproportionsothatthegravelgradingiscontinuous,theconcretehasgoodworkability,andusealargehopperforpouring,andaddawaterproofplugtopreventconcretesegregation.9.Theouterwallofthepilecasingshallbecleanedintimewhenthepilecasingisloweredandpulledout.Forexample,asmallpressurizedwatergunshallbeusedtowashtheholesdrilledineachshift.Thesemeasurescanreducethefrictionofthesidewallofthepilecasing.10.Controltheliftingheightofthepilecasingatonetimetoavoidexposingtheconcretesurfaceattherootofthepilecasingandcausingqualitydefects.11.Theliftingofreinforcementcageshallbestrictlyandcarefullycontrolled,andshallbefirmlybondorspot-weldedattheorifice.Afterthereinforcementcageentersthehole,checkwhetheritisinthecenterofthepilehole.Whenloweringthepipedown,theyshallbeplacedalongthecenterofthepileholetoavoidgettingcaughtinthereinforcementcage.ConstructionPlan(I)BoredCast-in-placePilewithSlurryWallProtectionInthesoftsoilareawithhighgroundwaterlevel,theconstructionofdryboredcast-in-placepilesoftencausesdifficultiesintheconstructionofboredpiles,suchasqualityaccidentslikeholecollapseandnecking.Therefore,inordertoensuretheholeformingquality,mud-protectionwallmeasuresshouldbetakentoprotecttheholewallwithmudtopreventholecollapseandtheformationofpileholesbydischargingsoilslag.ConstructionPlanBoredCast-in-placePilewithSlurryWallProtection（I）BoredCast-in-placePilewithSlurryWallProtection（a）Drillinghole;(b)Placethepipeandreinforcementcage;(c)Pourunderwaterconcrete;（d）FormationofpileTheboredcast-in-placepilewithslurrywallprotectionisapileformedbyusingslurrywallprotection,dischargingthesoilslagcutbythedrillbitoutoftheholethroughcirculatingslurryduringdrilling,andthenliftingthereinforcementcageandpouringconcreteunderwater.Accordingtotheholeformingmethods,therearepositive(negative)circulationrotarydrillbore,positive(negative)circulationsubmersibledrillbore,impactdrillbore,punchingandgrabbingconedrillbore,drillbucketdrillbore,etc.Theconstructionprocessisshowninfigure4-2-6(constructionprocessofboredcast-in-placepilewithslurrywall).1.ConstructionPreparationCommonlyuseddrillingmachinesincluderotarydrillingmachinesandsubmersibledrillingmachines.(Fig.4-2-7),Percussiondrill(Fig.4-2-8),Grab-typedrillbit(Fig.4-2-9)etc.Fig.4-2-7UnderwaterrigFig.4-2-8PercussiondrillFig.4-2-8Grab-typedrillbitBoredCast-in-placePilewithSlurryWallProtection2.TechnologicalProcessFig.4-2-10Constructionprocessofboredcast-in-placepilewithslurrywallprotectionBoredCast-in-placePilewithSlurryWallProtection2.TechnologicalProcessBoredCast-in-placePilewithSlurryWallProtectionSpecificationsandStandardsUnifiedStandardforConstructionQualityAcceptanceofBuildingEngineeringGB50300TechnicalSpecificationsforBuildingPileFoundation（JGJ94-2008）TechnicalSpecificationsforTestingofBuildingFoundationPiles(JGJ106-2003)LifelongLearningBoredCast-in-placePilewithSlurryWallProtectio2.KeyPointsofConstruction(1)DeterminationofPilePositionAfterlevelingandclearingtheconstructionsite,setthepositioningpointandbenchmarkofpilefoundationaxis,determinethepositionofeachpileaccordingtotheconstructiondrawingofpilelocationplanelayout,andmakesigns.Beforeconstruction,thepilepositionshallbecheckedandrecheckedtopreventdeviationcausedbyexternalfactors.3.KeyPointsofConstructionPilecasingburying（2）PileCasingBuryingThepilecasingismadeofsteelplateof4~8mmthick,theinnerdiameteris100~200mmlargerthanthedrillbitdiameter,thetopsurfaceis0.4~0.6mhigherthantheground,and1~2slurryoverflowholesareopenedattheupperpart,asshowninFigure4-2-11.Theroleofthepilecasingistofixthepileholeposition,preventsurfacewaterfromflowingin,protecttheorifice,increasethewaterpressureinthepilehole,preventholecollapse,andguidethedirectionofthedrillbitduringholeformation.Thepilecasingshallbeburiedbeforedrilling.Whenthepilecasingisburied,thetopsoilatthepileholeshallbeexcavatedfirst,andthepilecasingshallbeburiedinthesoil.Theburieddepthshallnotbelessthan1minclayand1.5minsand.Theheightshallmeettherequirementsfortheheightoftheslurrylevelinthehole,andtheslurrylevelintheholeshallbekeptmorethan1mhigherthantheundergroundwaterlevel.Whenpitexcavationisadoptedforburying,thediameterofthepitshallbe0.8~1.0mlargerthantheouterdiameterofthepilecasing.Thedeviationbetweenthecenterofthepilecasingandthecenterlineofthepilepositionshallnotbegreaterthan50mm.Afteralignment,theoutsideofthepilecasingshallbefilledwithclayandcompactedinlayers.BoredCast-in-placePilewithSlurryWallProtectio3.KeyPointsofConstructionPileDriverinPlaceBeforeplacingthedrillingrig,theperipheryofthepileholeshallbeleveledtoensurethatthedrillingrigisplacedinplaceandthemachinebodyisstable.Whenthedrillingrigisinplace,itshallensurethatthechassisoftheframe,thecenterofthedrillbitandthecenterofthepilepositionareonthesameplumbline,andthecenteringerrorshallnotbegreaterthan20mm;Afterthedrillingrigisinplace,measuretheelevationofthedrillingrigplatformtocontrolthedrillingdepthandavoidoverdrillingorunderdrilling.Afterpassingtheself-inspection,fillintheinspectionapplicationformandaskthesupervisingengineertocheckthealignmentofthedrillingrig,thechassislevelandtheverticalityofthedrillpipe.Drillingcanbestartedonlyafterthesupervisingengineerhascheckedandaccepted.Beforetheformaldrilling,thedrillshouldfirstruntest,checktheconcentricityofthedrillbitandthestabilityofthedrill,toensurethatthesubsequentdrillingconstructioncancontinue.BoredCast-in-placePilewithSlurryWallProtectio（4）PoreForming①Slurrypreparation.Theslurryisusedtoprotectthewall,carrysandfordumping,cutsoilforlubrication,coolthedrillbit,etc.,amongwhichthemainfunctionistoprotectthewall,asshowninFig.4-2-12.Theslurrypreparationmethodshallbedeterminedaccordingtothesoilconditions:Whenformingholesinclayandsiltyclay,cleanwatercanbeinjectedtomakeslurryfromtheoriginalsoil,andthedensityofslagdischargeslurryshallbecontrolledtobe1.1~1.3g/cm3;Whenformingholesinothersoillayers,theslurrycanbepreparedfromclayorbentonitewithhighplasticity(Ip≥17);whenformingholesinsandysoilandthicksandlayer,themuddensityshallbecontrolledtobe1.1~1.3g/cm3;Themuddensityshallbecontrolledtobe1.3~1.5g/cm3whentheholeisformedinthesoillayerpassingthroughthesandgravellayerorthesoillayereasytocollapse.Duringconstruction,muddensity,viscosity,sandcontentandcolloidratioshallbemeasuredregularly.Thecontrolindicatorsoftheslurryareviscosityof18~22s,sandcontentofnomorethan8%andcolloidrateofnolessthan90%.Inordertoimprovetheslurryquality,additivescanbeadded,suchasweightincreasingagent,viscosityincreasingagent,dispersant,etc.Themudandsludgediscardedduringconstructionshallbedisposedofaccordingtotherelevantprovisionsofenvironmentalprotection.BoredCast-in-placePilewithSlurryWallProtectio3.KeyPointsofConstruction②Slagremovalmethodinporeformingprocessa.SlagextractionbyslagextractorTheslagdischargestructureoftheslagextractorissimple(Fig.4-2-13)withconvenientoperation.Generally,thedrillbitshallbetakenoutoftheholeandputintotheslagextractor.Thelowervalveshallbeopenedandthesludgeshallentertheextractor.Lifttheslagextractorandthevalveshallbeclosedunderthegravityofthesludgeintheextractortodischargethesludgeoutofthehole.Fig.4-2-13Structuraldiagramofslagextractor（a）Bowlvalve;（b）Singleleafvalve（c）DoubleleafvalveBoredCast-in-placePilewithSlurryWallProtectio3.KeyPointsofConstruction（4）PoreForming②Slagremovalmethodinporeformingprocess

b．Slurrycirculationslagremovalmethod

canbedividedintopositivecirculationslagremovalmethodandreversecirculationslagremovalmethod,asshowninfigure4-2-14.Fig.4-2-14Slurrycirculationporeformingprocess（a）（a）Positivecirculationslagdischarge;（b）（a）Positivecirculationslagdischarge;1-Drillpipe;2-Watersupplypipe;3-host;4-drill;5-Sedimentationtank;6-Submersiblemudpump;7-Slurrypit;8-Gravelpump;9-Slagextractionpipe;10-Slagremovingcapsule（a）Thepositivecirculationslagremovalmethodisthatthemudissprayedfromtheendofthedrillpipealongthedrillpipefromtheinsideofthedrillpipe,andthesoilslagcarrieddownflowsupwardalongtheholewall.Thesoilslagiscarriedoutfromtheorificeandflowsintothesedimentationtank.Thesettledmudflowsintothemudpitandispumpedintothedrillpipebythepump.Inthisway,thesettledmudslagistransportedoutofthesitebythemudtruck.（b）Thereversecirculationslagremovalmethodisthatthemudflowsintothemanholefromtheorifice,andthesandpumpsuckstheslagalongthedrillpipe,sot