软基处理粉喷桩施工控制Construction control of soft foundation treatment powder spraying pile.docx

软基处理粉喷桩施工控制Construction control of soft foundation treatment powder spraying pile.docx

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软基处理粉喷桩施工控制Constructioncontrolofsoftfoundationtreatmentpowdersprayingpile

软基处理粉喷桩施工控制（Constructioncontrolofsoftfoundationtreatmentpowdersprayingpile）

Softfoundationtreatmentcontrolpileconstruction

Wangrongqin

（JiangxiroadandBridgeEngineeringBureau,Nanchang330000）

Abstract:

Aimingatthesoftsoilroadhighfillsubgradesettlementisdifficulttocontrol,throughthesoftsoilfoundationtreatmentofDJMpileMaWuhighway

Thesuccessfulpractice,aimstointroducetheexperienceandmethodofvariousconstructionofpowdersprayingpilein.

Keywords:

roadengineering;softfoundation;pile;control

0Introduction

MaWuhighwaysubgradeengineeringK36+050-K38+652sectionbelongstotheYangtzeRiverarea.Thesoftsoilcomplexcauses,formationofdiversesoilstructure,thespatialdistributionoflarge,complex.Thethicknesschangeofsoftsoil,thebigdifferenceofproperties.Accordingtothegroundexplorationthatisdividedintothreelayers:

theIlayergeologicalsoftplasticclayoflowliquidlimitdistributioniscontinuous,thedepthof0-2.3m.TheIIlayerintheplasticflowofsiltoflowliquidlimitclay,forlocalsiltoflowliquidlimitsilt,sandwichedbetweenthelowliquidlimit,lowlimitsiltysandclay,depthofabout2.3-7m.TheIIIlayertosoftandhardplasticclayoflowliquidlimitshape,sandwichedbetweenmediumdensesiltysandsoil,lowcompressibility,thedepthisabout7-14m.

Throughthecalculationandanalysisofdeepfoundationtreatmentinsmallstructuresandbridgeabutment,designusingpowderjettingmixingpile（dry）softfoundationtreatment,tocontrolthestructurethroughthespacingofDJMpilesettlementafterconstruction.

1constructionprinciple

1.1oftheoriginalfoundationstructure

Showthatthestructureoftheoriginalfoundation:

naturalwatercontent,naturalvoidratioistoolarge,thebearingcapacityofnaturalsoil.Throughthepilefoundationtoimprovethebearingcapacityofthewhole.Cementsoilpileinthebodyshowedthatthestrengthofcementsoilandcementhydrationhydrationofthesilicatehydrate（CSH）theamountofapositivecorrelationbetweentheroleofCSHinthecementsoiliscementation,soastoreducetheeffectoftheoriginalnaturalsoilporeratio,andcementsoilmoisturetoreducetheratioof4%-8%contentashbeforethenaturalsoilmoisturecontent

1.2pileconstruction

Constructionofpowdersprayingpileisthroughtheturbinebladeofthedrillwithcementpowderandclayforcedmixing,soastoimprovethebearingcapacityofthefoundation.

2ConstructionTechnology

Byspraypowderpilespecialmechanicalequipment,deepcapacityofnotlessthan18m,pilediameter50cm,constructiontechnology:

PileLofting-driller-testpilemachinelevelingbody--highpressuregassprayholedrillingtoopen--thedesigndepth-reversaldrillingmudpowderandsprayingtotheoriginalgroundfollowing30cm-stop-dustingrepeat-turnuptothesurface,mixingpileconstructionunderapileend.

3designparameters

3.1strengthparameters

28daysthecorestrengthofR28isgreaterthan0.8Mpa,90daysofagethecorestrengthofR90isgreaterthan1.2Mpa,90daystodostaticloadtest,thebearingcapacityofsinglepileisgreaterthan140Kpa,morethan120Kpaofbearingcapacityofcompositefoundation.

3.2settlementcontrolstandard

Controlstandardfor0.2mgeneralsettlementofembankment;controlstandardculvertstructuresandthesettlementis0.2m;thecontrolstandardofabutmentofbridgesectionofthesettlementis0.1m.

3.3accordingtotheregulations

Theconstructionsiteinstrictaccordancewiththe"standard"implementationoftheconstructionofsoftfoundationtreatment（seeTable1）

Table1

Beijing

project

Company

Theallowabledeviation

Checkmethodandfrequency

One

Pilespacing

Cm

+10

Check2%

Two

Pilediameter

Mm

Notlessthandesign

Check2%

Three

Pilelength

Cm

Notlessthandesign

Checktheconstructionrecord

Four

Verticaldegree

%

Notlessthandesign

Checktheconstructionrecord

Five

Theamountofpowderinjectionpile

%

Notlessthandesign

Checktheconstructionrecord

Six

Strength

Mpa

Notlessthandesign

Check0.5%

4preconstructionpreparation

4.1rawmaterials

The32.5Portlandcementbagsdesignatedbytheownerofpilereinforcementmaterials,projectDepartmentofcementprocurement,storageanduseofunifiedmanagement.Afterenteringthesitestoredincementcementshed,inordertoavoidthecementintheshedindamp,onthegroundonboardthebracketforsupportingpad.Cementstorage,afterstrictregistrationofcementaccount,

Inordertoconformtothenumberandamountofcementpowdersprayingpiletimelycheckdoneeverydayintheconstruction.Everybatchofcementafterenteringthelaboratory,theprojectdepartmentinatimelymanneraccordingtothefrequencyofsampling,detectionofvariousphysicalpropertiesofcement,whennecessarytosenddirectorsampling.

4.2ashratiodetermination

4.2.1soilphysicalpropertiestestpile,theprojectdepartmentlaboratorywillbeselectedwithnaturalsoilrepresentativepositionfordrillingatdifferentlevels.Thephysicalpropertiesofthesoilsamplestakenoutexperiments（seeTable2）:

Table2

Theindicators

Soilcategory

depth

natural

watercontent

natural

voidratio

Compressionmodulus

（Mpa）

Compressioncoefficient

（Mpa-1）

Firstfloor

0-2.3m

36.4%

Onepointzerothreeone

Threepointfourseven

Zeropointfivenine

Firstfloor

2.3-7m

37.6%

Onepointzerofivetwo

Threepointonethree

Zeropointsixthree

Thirdlayer

7-14m

55.5%

Onepointsixonefive

Onepointeightnine

Onepointthreeeighttwo

4.2.2admixtureisdeterminedby45kg/m,50kg/m,55kg/mindoorthreeashdosageratioandcompressivestrengthtestsshowthatwiththeincreaseofcementcontent,thespecimenoftheunconfinedcompressivestrengthincreasedsignificantly（seeFigure2）;anddifferentadmixtureofcementwiththegrowthoftheage,theunconfinedcompressivestrengthincreasedsignificantly（seeFigure3）.Theprojectinthepremiseofensuringthequality,costsaving,admixtureselection50kg/m.

Figure1,figure2

Throughtheindoor4.2.3ratiototestpilebypiletesttodeterminethenumber,quantity,stirringspeed,enhancedrillingashcementpressurevelocityandcementpumpparameters.Thissectionconsistsof10rootpile,andthepilemustbesuccessfulbeforetheconstructionofpowdersprayingpileinlargescale,afterpilecoresamplesofunconfinedcompressivestrengthasthestandardstrengthofpilebody.

4.3detectionequipment

Theconstructionbeforethedetectionmeterpilerigandprintingequipmentintegrity,accuracy.Computermeteringdevicemustbesenttotheunitsabovethecitycalibration,check,labelsealbeforeconstruction.

4.4siteleveling

Thissectionpileareintheditch,inordertoensurethesmoothconstructionofconstructionequipmentintheconstructionsite,thesitelevelingisveryimportant,theoriginalpondditchbackfill,levelingnecessary.

4.5withthecorrespondingsign

Iftheconstructionparametersigns,constructionresponsibilitycard.Thepileintheconstructionprocess,theprojectdepartmentandtechnicalpersonnelwith24hoursofthewholeprocessofsiteowneranddirectorofshift,24hoursatanytime,accordingtothesigncontentandfieldcheckcard.

5constructioncontrol

5.1constructionlofting

Intheconstructionofpowdersprayingpile,accordingtoroadbedwidthanddesignparametersinconstructionofpileplanecanvasmap.Figureouttheconstructionareaofpileaccordingtothesampleineachregionaccordingtothedesignofpilespacingpilelofting.Thepositionofpileabutment,toensurethepileandpowderspraypilehascertaindistance,toensurethatthepileconstructiondoesnotcollapse.

5.2fieldcontrol

Theprojectdepartmentstaffresponsiblefortheconstructionofpowdersprayingpile,pileconstructionrequirementsfor24hoursofon-site,andallconstructionpersonnel（includingtechniciansandconstructionworkers,Captain）requirementsforemployment,constructionequipmentrequirementsarenumbered,thehosttowereverymline（superscriptrequiresareflectingsign）,somasterthedrillingdepth,mixingdepth,mixingspeed.

5.3inordertoensuretheverticalityofpileconstructioncanmeettherequirementsofdesignorspecification,putahammerinthehosttower,thedrillleglifttoadjusttheverticalityofthehosttower,soastoensurethedrillpipeandtheverticalityofpilebody.

5.4inspectionequipment

Siteconstructionpersonneltoopenthemeterandchecktheprinterbeforedrillingrigintegrityandaccuracy.Checkcompletetheconstructionofthetechnicalparametersofeachpiletoprintoutthecomputersmallticket,donotmeetthedesignrequirementsofthepiletotaketimelyremedialmeasures.

5.5siteconstructioncontrol

The5.5.1drillrigtocontrolthespeedofslowstartdrilling,normaldrillingspeedchange,whenthebitisclosetothedesigndepthrestoreslowdrilling,

Thedrillturns1mininsitu.Inordertoensurethedrillpipeinthedrypowderfeedingchannel,fromthebeginningtothedrillingduringcontinuousdeliveryofcompressedairspray.

5.5.2powdermixintheconfirmationofcementpowderspraytotheholebottom,toenhancethespeedof1.08m/minreversal,inthepromotionatthesametimecontinuousspray.Whentostopashdesignelevation,shouldbeslowinsitumixing1-2min.

5.5.3repeatstirringpiletoensurethecementpowderwillbemoreuniform,thedrillbittothedesigneddepthagain,enhancethemixingspeed,stillunderthecontrolof1.08m/min.

5.6theconstructionsiteshouldpayattenti