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MAY2015,VOLUME17,ISSUE3.
ISSN1392-871611051579.
HardrockdeepholecuttingblastingtechnologyinverticalshaftfreezingbedrocksectionconstructionZhitaoZheng1,YingXu2,JianghuiDong3,QiZong4,LipingWang51,2,4AnhuiUniversityofScienceandTechnology,Huainan,232001,China3SchoolofNaturalandBuiltEnvironments,UniversityofSouthAustralia,Adelaide,SA5095,Australia5SansomInstituteforHealthResearch,SchoolofPharmacyandMedicalSciences,UniversityofSouthAustralia,Adelaide,SA5001,Australia2,3CorrespondingauthorsE-mail:1zztzheng@126.
com,2yxu@aust.
edu.
cn,3jianghui.
dong@unisa.
edu.
au,4qzong@aust.
edu.
cn,5liping.
wang@mymail.
unisa.
edu.
au(Received7January2015;receivedinrevisedform25March2015;accepted11April2015)Abstract.
Usingthetraditionalcuttingblastingtechnologyinverticalshaftconstructionhassomefeatures,e.
g.
slowsdrivingspeed,ganguewithlargevolumeandthrowinghigh.
Moreover,largeexplosivechargeinitiationhasaseriousinfluenceonfreezingpipesandfreezingwall.
Inthisstudy,theperipheryholechargeandchargestructurewasoptimized,andtheblastingmodelofthebedrockverticalshaftsectionwasestablishedbyusingtheANSYS/LS-DYNAnumericalsimulationsoftware.
Inaddition,stressconcentrationofthelargediameteremptyholeanditsinfluenceofblastingefficiencyinblastingwereanalyzed.
Thefieldexperimentwasconductedtoverifytheblastingresults.
Theresultsshowthatusinglargediameteremptyholeblastingtechnologyinverticalshaftconstructionoffrozenhardrocksectioncansignificantlyimprovethespeedofverticalshaftconstruction,obtaintheexcellentblastingeffectandguaranteethesafetyoffreezingpipesandfreezingwall.
Keywords:deep-holeblasting,freezingbasementrocksection,hardrock,largediameteremptyhole,verticalshaftsinking.
1.
IntroductionConstructionofverticalshaftisakeyprojectinmineconstruction[1].
Engineeringquantityofverticalshaftaccountsfor5%oftotalprojectamountofmineconstructionproject.
Atpresent,intheconstructionprocessofthemine,verticalshaftcostaccountsfor~20%-30%oftotalconstructioncostsofmine.
Verticalshaftprojectgenerallyaccountedfor~40%-50%ofthetotaltimelimitofmineconstruction[2-5].
Therefore,itisimportantformodernmineconstructiontoimproveconstructiontechnologyofshaft,improvetheabilityofshaftdrillingequipmentandacceleratetheconstructionspeedofverticalshaft.
Freezingsinkingofverticalshaftwhichthroughunstablesoilcoverorjointdevelopmentisoneofthemosteffectiveconstructionmethodsinbedrocksectionofalargequantityofwatergushing[6,7].
Whenthefreezingconstructiongetsthroughtheunstablesoilcover,thedrillingandblastingmethodwillnotbeusedintheconstruction.
Thisensuresthatfreezingwalllessenteredthewilddiameterinfreezing.
However,withtheincreasingincoalminingdepth,alargenumberofshaftsneedthroughthehardsandstrata.
Accordingtothegeologicaldataandexperimentaltest,sandstonerocksolidcoefficientmostlyis~7-10,upto~16,itisdifficulttodrillandblast,andgreatlyaffectthetunnelingspeedofshaft.
Infrozenhardbedrockmineverticalshaftconstruction,notonlytoimprovethespeedofconstruction,butalsotoensurethesafetyoffreezewallandfreezepipes.
Therefore,researchersinvariouscountriesareexploring.
Xieetal.
studiedfrozensoilmechanicsindex,suchasthestrengthofthefrozensoil,thedeformation,constitutiverelation,creepandstressrelaxation[8].
Lingetal.
reachedaconclusionthroughexperiments,thedifficultyoffrozensoilblastingconsistentwiththewavevelocityfrombigtosmallorderforthesamekindoffrozensoil,andP-wavevelocityoffrozensoilreflectstheblastabilityoffrozensoilsignificantlythantheS-wave[9].
Lietal.
throughthefrozensoilsmoothblastingparametersexperimentwhichtakesfrozen1579.
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ISSN1392-8716sandasprototype,toprovethefeasibilityoftheimplementationofthesmoothblastinginfrozensoil[10].
Yangetal.
usednumericalmanifoldmethodtocarryonseveralsimulations,theformationanddevelopmentofcracksunderimpactloadingintheprocessofdouble-holeblasting,theformationanddispersionofblock,andtheformationprocessofblastingcrater,thecalculationresultsdeepentheunderstandingofrockfailuremechanismandmillisecondblastingeffect[11].
Wangetal.
studiedthedeepholeblasting,throughtheanalysisofblastholedepth,holeconcentrationdegree,andtherelationshipbetweenblastingcratervolumeandtheamountofexplosive,pointedoutthatdeepholeblastingcanbeusedinverticalshaftconstructionoffrozenhardrocksection[12].
Deyetal.
pointedoutthatcuttingformsofverticalshaftdeepholeblastingareparallelcylindricalcuttingandinclinedtaperedcutting,usedeepholeblastingcanincreasethedrivingspeedverticalshaft[13].
Lietal.
predictedthedegreeofcompactionandoptimizedthedistributionofblastholesbysimulationmodelandexperimentdata[14].
Quetal.
carriedoutanexperimentoninclinedtaperedcuttingblasting,theinclinedtaperedcuttingbottomholesarecloselytoeachother,explosivesarerelativelyconcentrated,therockinthecircleofcuttingholecangethighblastingenergy,theexperimentalresultsshowedthatthecuttingeffectisexceedinglygoodinhardrocktunneling[15].
Lietal.
conductedasimulationoflargediameteremptyholespiralcuttingblastingcavityformingprocess,andpointedoutthattheemptyholecanprovidefreeblastingsurfacetoimprovingtheblastingfootage[16].
Intheabovestudy,deepholeblastingtechnologyisthemainmethodtoimprovethespeedofexcavationofverticalshaft,andlargediameteremptyholeblastingtechnologyhasneverbeenusedinfrozenhardbedrocksectionverticalshaftconstruction.
Recently,cuttingformsofverticalshaftdeepholeblastingareparallelcylindricalcuttingandinclinedtaperedcutting.
Ininclinedtaperedcuttingblasting,energyconcentratedandcrushingganguethrowinghigh.
Thecrushinggangueoftencollapsesinkingmachineryequipmentinwell,moreover,drillingprecisionofinclinedtaperedcuttingisnoteasytocontrol.
Thus,thismethodisrarelyappliedinpractice.
Parallelcylindricalcuttingblastingcanbeverywellovercometheabovedisadvantages,andgetbettercuttingeffect.
However,blastinggangueoftenappearsinhighboulderyieldindeepholeblasting,bringinconveniencetotheganguecleaning.
Inordertosolvetheaboveproblems,inthisstudy,largediameteremptyholeblastingtechnologyisappliedinfrozenhardbedrockmineverticalshaftconstruction,peripheralholeadoptthesmoothblastingtechnique.
ThelargediameteremptyholestressconcentrationinthecourseofblastingwasanalyzedbyANSYS/LS-DYNA,throughthefieldexperimentteststheembrasureutilizationofverticalshaftfreezehardbedrockdeepcuttingblastingtechnology.
Thisresearchhastheoreticalandpracticalguidingsignificanceofverticalshaftrapidconstructioninfrozenhardbedrocksection.
2.
Mathematicalmodels2.
1.
LargediameteremptyholesblastingmechanismInordertoincreasethecuttingeffect,drillinglargediameteremptyholeinthecenterofthewellbore,theemptyholecanbedrilledaround~40-50m.
Accordingtothecurrentresearch,beatemptyholeblastingintheroleofthefollowingthreeaspects[16-21].
2.
1.
1.
StressconcentrationandguidingroleStresswaveswillprovokearoundtheboreholeandspreadaftertheexplosivesdetonate,thishigh-impactactionstartsfromtheholewalltoactivatethemicro-cracksneartherockandmakeitexpand.
Stresswavespreadtolargediameteremptyhole,andproduceareflectionintheemptyhole.
Becausethereflectionofstresswave,thestressnearbytheemptyholewallwilllargerthanwithoutemptyholes,thatshowsthestressconcentrationeffectoftheemptyhole.
Theexistenceofemptyholechangedstressstatesofboreholeisotropiccompressiongeneratedaftertheadjacent1579.
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ISSN1392-87161107detonating.
Thestressinducedcrackgiveprioritydevelopmentinthedirectionofalineofslotandtheemptyhole,theotherdirectionofcrackextensionwasinhibited.
Meanwhilethereflectionofstresswaveinthewalloftheemptyholesenhancedstretchingactioninthatdirection.
Whenthereflectedtensilewavepropagationoftheexplosionisnearthesourceofcrackactivationzone,willguidethedetonationgasdirectionalacceleratedpropagationofcracks,sotheexistenceofemptyholeplaysaguidingroleoffracture(Fig.
1).
InFig.
1,–additionalradialexplosionatapointintherockstress,MPa;–explosionatapointintherockshearstress,MPa;–blastholeradius,m;–emptyholeradius,m;–blastholeandemptyholecenterdistance,m;–calculationofpointtolineandangleholecenterholeandemptyholeconnection.
Slotsapproximatelycoupledcylindercharges.
Assumingthechargeholeexplosiveforblastingatthesametime,theblastholeAafterinitiation.
Explosivestresswaveisarousedinthesurroundingrock,andtheoutwardpropagation,alongwiththeincreaseofdistance,thestresspeakvalueofblastholeAaccordingtocertainattenuationlawas[16,17]:=,(1)=,(2)where–theinitialpressureofexplosiveactsontheholewall,MPa;–thedistancefromtheblastholecentertoapointontherock;–stresswaveattenuationcoefficient,=2(1),–therockdynamicPoisson'sratio.
ThePoisson'sratioofrockisrelatedtothestrainrateanditdecreaseswiththeincreaseofstrainrate,therelationshipbetweenthedynamicPoisson'sratioandstaticPoisson'sratiois=0.
8.
–dynamiclateralstresscoefficient=(1).
WhenthestresswavetoBhole,becauseofthereflectionofstresswave,stressneartheBholewillbelargerthanBwithoutemptyholes,thestressperformanceofanemptyholeconcentrationeffect.
Basedonthetheoryofelasticmechanics,thepeakofBneartheholestressstateisexpressedas[16,17]:=12(114+3)cos2+cos2,(3)=12(11+3)cos2+cos2,(4)=12(1+23)cos2+cos2,(5)=,(6)where,–radialemptyholestressconcentrationstressinrock,MPa;–shearstressconcentrationintheairtorockstress,MPa;–emptyshearstressconcentrationafterrockstress,MPa;–distancefromtheemptyholecentertoapointintherock,m.
When=,=0,=0,theboundaryconditionsaretakenintoEq.
(4):=+2cos2+cos2,(7)canbeobtainedfromEq.
(7)and=0,when=±:=3+=(1+3).
(8)Bytheanalysisofstressconcentrationeffecttheory,maximumtensilestressoccursinthe1579.
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ISSN1392-8716emptyholewallinconnectionwithslot,andwiththeincreaseofemptyholediameter,moresignificantroleinguiding,thegroovecavityofthebrokenrockzoneisbigger.
2.
1.
2.
FreesurfaceeffectThepurposeofstraightslotistoprovideafreesurfaceforthecavingblastingoffollow-updelayeddetonation.
Theexistenceofemptyholeprovidesfreesurfacefortheblastingcutting.
AsshowninFig.
2,accordingtothebasicprincipleoffluidmechanics,inthestraightholeblastingwithemptyhole,blastholeexplosionmakestherockmediumbetweenblastholeandemptyholebroken,andfirstofalltoemptyholedirection,withthehelpofemptyholefreesurface,correspondingtotheemptyholewallproducestheimpactofthereboundandformingthetensilestresswaves,duetothelowdynamictensilestrengthofrock,causestherockbegantoflakeofffromtheemptyholewalltochargeholedirection,formingagroovecavity.
Whentheemptyholediameterincreases,strengtheningtheemptyholereflection,thereflectedtensilewavescopealsoincreases,whichismoreconducivetotherock.
Fig.
1.
StressconcentrationeffectanalysisdiagramoftheemptyholeFig.
2.
FreesurfaceeffectanalysisdiagramoftheemptyholeInthestraightholeblasting,thethrowingdirectionofrockbrokenapproximatelyverticaltotheemptyholewall.
Theformationofbrokencuttingmainlytotheimpactofshear,whenthepermeterholechargeiscertain,optimalspacingofisafunctionoftheemptyholediameter,canbeapproximatedsolvingbynumerical.
AccordingtotheNewtoniterativemethod,combinedwitheachmeterblasthole'schargecalculationformulaofcuttingchargeholes,weobtainthefollowingfunction[18,19]:()=2+29)where=16,–permeterholecharge,kg/m;–blastholeradius,m;–emptyholeradius,m;–chargedensity,kg/m3;–chargedetonationvelocity,m/s;–blastingofrockdensity,kg/m3;–blastholeandemptyholecenterdistance,m;–theinitialvelocityofrockthrowing,m/s;–averagespeedofcrackpropagationinrockmassexplosion,m/s;[]–theshearstrengthofrock,N/m2;–chargingcoefficient,cutholeiscalculatedbasedon~0.
6-0.
8.
Eq.
(10)isderivedfromEq.
(9):′()=3+2[2[]+,(10)where=+2Newtoniterativeformulais:=()(),=0,1,2,….
(11)1579.
HARDROCKDEEPHOLECUTTINGBLASTINGTECHNOLOGYINVERTICALSHAFTFREEZINGBEDROCKSECTIONCONSTRUCTION.
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ISSN1392-87161109Theabsolutevalueofthedifferenceoftwoadjacentshallmeettheconditions:||<0.
0001.
Forshale,[]=3*107N/m2,=2700kg/m3,the2ndexplosives,=1000kg/m3,=3600m/s;otherparameters=0.
7,(medicinecolumnradius)=0.
014m,=0.
016m.
TherelationshipbetweenholespacinganddiameterofemptyholewasobtainedbyusingBASICprogram(Fig.
2).
a)b)Fig.
3.
RelationshipbetweenholespacinganddiameterofemptyholeFig.
3(a)shows,theoptimalholespacingwiththeemptyholediameterincreased,butfromFig.
3(b)showstheoptimalholespacingandtheemptyholediameterratiowasdecreasedwiththeincreaseofemptyholediameter.
Containingparallelholecutblastingholelayoutwayisvaried.
Thecalculationmodelisusedonlyforthecalculationofrelevantparametersofemptyholedistancenearestblasthole.
Otherchargescandeterminetheoptimalresistanceaccordingtotheactualblastingfreesurfacewidth.
Byasimilarmethod,freesurfacewidthandtheoptimalresistancearegivenby[16,18]:=82[]+14+,(12)where–optimalresistance,m;–freesurfacewidth(verticalwiththrowingdirection),m.
OthersymbolsarethesameasthesymbolsinEq.
(9).
2.
1.
3.
ShearfailuretheoryAsshowninFig.
4,theblastholeblasting,rockparticleradialdisplacementoccursundertheactionofthecompressionstresswave,isthespeed.
Fortherockmediumofwelllaneworkingface,exceptforOEandOFbelongtotheinfinitebody,withinOEandOFbelongtolimitedmediumbody,chargeafixedvalueresistance,thusthetworanges,particlesuffereddifferentresistanceintheprocessofmoving,themovingspeedisnotthesame.
ThishasresultedinthemobileOEandOFfaceinternalandexternalsideofrockypointexistsavelocitygradient,inevitablyproducesshearstressonOEandOFsurfaces.
Inaddition,duetothepressuresideeffects,rockradialcompression,tensilestresswillexistinthetangentialdirection,soOEandOFfacenotonlytheexistenceofshearstressatthesametimealsothereistensionstress.
Therockisfragilebody,thetensileandshearcapacityisrelativelysmall,thustheroleofthesetwokindsofstress,OEandOFsurfacegeneratetensileshearfailure,theformationofcracks,rockwithinOEFOandoriginalrockseparated,andthrewtheemptyholesbythedetonationgasexpansiondrivenforce.
TheprojectilealongtheOEandOFsurfacedamageisshearfailureortensilefracture,mainlydependsontheemptyholediameter(freesurfacewidth)andtheemptyholeandtherelativeratioofchargeholecenter.
Whenconsideringthecutblasting,theclampingeffectofrockisrelativelylarge,thatrealizationofcuttingmainlytoovercometheshearstrength00.
511.
52581114Empetyholediameter(m)E-2Empetyholedistanceanddiameterratio1579.
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ISSN1392-8716ofOEandOFsurface,andmaketheprojectilehasacertaincastspeed.
Fig.
4.
Analysisofshearfailure2.
2.
SecurityoffreezingpipesafetymeasuresInadeepholeblastingofverticalshaftfrozensoil,theeffectofblastingtofreezingpipessafetyisrelatedtotheexplosivestresswavevelocitytransferintherockandrockproperties.
Forsandstone,detonationwavepropagationvelocityshowsagrowthtrendbytherockwalltooutside,inthepeakandthenattenuation,andgraduallystabilized,closetotheoriginalstresszone.
Becauseoftheinfluenceofblasting,therockloosecirclearoundthewellboreformation,accordingtothefreezingconstructionexperience,freezepipeslocatedoutsidetherockloosecircle,willnotoccurtobrokenpipesincidentsforblasting.
Freezingpipesfromthesurroundingtheeyeisveryclose,sothechargecontrolsofperipheryholesandanexplosiveofignitionandadoptreasonabledelaytimeisthemainmeasurestoensurethesafetyofthefreezingpipes.
2.
2.
1.
PeripheryholechargecalculationandchargestructureTheempiricalformulaofthecontrolofperipheryholesexplosivechargeis[22]:=1.
55,(13)where–peripheryholemaximumcharge,kg;–peripheralholedistance,m;–peripheralholeinfreezingdistance,m.
Whenthedistancebetweenfreezingpipeandholewallislessthan1.
2m,theaboveformulaavailableperipheryholecharge;equaltoandgreaterthan1.
2m,canaccordingtothelightexplosionrequirementscalculatetheperipheralwholecharge.
Inordertoachieveacutgoodblastingeffectandensurethesafetyoffreezingpipeswall,chargestructureusingradialcouplingwithlongitudinalairintervalcharge,peripheralholesuse35mmwatergelexplosivecharge,nocouplingcoefficient=1.
43,longitudinalhaveacertainlengthofairgaplongitudinalhaveacertainlengthoftheairgap.
Theholebottomblastingwasusedinallgunports(Fig.
5).
a)b)c)Fig.
5.
Chargestructurediagram:a)peripheralholewithairintervalchargestructure;b)twoordercutholeandauxiliaryholeusingcontinuousloading;c)first-ordercutholewithsectionchargestructure.
1–pluggingmaterials;2–cartrige;3–detonator;4–firstdetonator;5–seconddetonator;6–crabstick;7–airlayer1579.
HARDROCKDEEPHOLECUTTINGBLASTINGTECHNOLOGYINVERTICALSHAFTFREEZINGBEDROCKSECTIONCONSTRUCTION.
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ISSN1392-871611112.
2.
2.
MillisecondblastingshockabsorptionAccordingtotheobservationdata,thecontinuationtimeofablastingvibrationisgenerally~4-8ms,butwedesignprimerdetonatorusedthe100msextension,soshocksuperposedmaynothappenedcausedbydifferentsegmentsofdetonator.
Therefore,wecanputtheperipheryholeinitiationasanindependentinitiationprocess.
Inthereasonableselectionofblastingparameteratthesametime,weshouldalsostrengthencooperationonconstructionandfrozen,stopbrinecirculationeverytimebeforeblasting,tocheckandcorrectafterblastingandthenresumenormaloperation.
3.
NumericalsimulationsInordertoimprovetheabilityofrockbreakingcomparisonoflargediameteremptyholeinthestageparallelholecutblastingeffect.
Comparisonofnumericalsimulationisadoptedinthisresearchcutblastingwithlargediameteremptyholeandtheemptyhole,cuttingholedividedintothefirststepgrooveeyeandthesecond.
Thegrooveeyesinthesameorderareinthesameinitiationtime.
Thedelaytimeofthesecondstepgrooveeyeis2000us.
Tofacilitatetheobservationoftheemptyholenearthestressandcrack,thisstudyestablishes1/2modelandusesthemodeltogeneratecompleteconditions[23,24].
3.
1.
ModelestablishmentInthe3Dmodelofshaftblasting,thetypeofmodelelementisSOLID164element.
Thesimulationmodel(800cm*400cm*600cm)isbuiltaccordingtothesizeofthewellbore.
Thelengthofthechargeis450cm,thestemminglengthis150cm,cuttingholediameteris50mm,emptyholediameteris100mm,cartrigediameteris40mm,cuttingholespacingis240cm.
Inthemodel,thenumberofrockelementsis408450,thenumberofexplosivematerialelementsis72396,thenumberoftampingplugmaterialelementsis53604,thenumberofairmaterialelementsis53867,thenumberofnodesis514552.
Thereflectionlesboundaryconditionwasappliedintheupside,rearandtwosidesofmodelsapplied.
Tosimulatetheclampingeffectofrockintheshaft,thefixedconstraintwasappliedattherearandtwosides.
Theundersideistheplaneofsymmetry,andsymmetricalconstraintwasimposedonthenodesofthesurface.
Accordingtotheactualsizeofthemodel,establishesthecuttingblastingmodelinANSYS10.
0.
Definingthepropertiesforeachkindmaterialbeforetheelementarydivision(Mainlyisthesimpledefinition,therealmaterialpropertyneedtogeneratetheKfilerightafterthechangeintheKfile).
Andthenonexplosives,stemming,airofrefinement,therockcontrollingelementsizereasonableonthesurfaceelementusesthesurfacesizecontrollerunitinthegridcontrol.
Finally,thesweepelementdivisionofrockmassV-sweepwasusedtoensuretheunitishexahedralelement.
Inordertodescribetherockrheologyontheactionoftheexplosionimpactplastichardeningsoftening,theelastoplasticconstitutiveequationwasusedtodescribetherockinthisstudy.
Thematerialmodelisrelatedtothestrainrate,sothestraincanbeconsideredtofailure.
Toselecttheisotropicorkinematichardening,hardeningparametercanbeadjustedbetween0(onlythekinematichardening)and1(onlytheisotropichardening).
TheCowper-Symondsmodelisusedtoestablishthestrainrate,withtherelevantfactorandstrainratethatyieldstress,whichcanbeexpressedasEq.
(14):=1++,(14)1579.
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ISSN1392-8716where–initialyieldingstress;–hardeningparameter;–rateofstrain;andarethestrainrateparametersoftheCowperSymondsmodel;–effectiveplasticstrain;–plastichardeningmoduluswasobtainedfromEq.
(15):=,(15)whereandareelasticitymodulusandtangentmodulus,respectively.
TheparametersinEqs.
(14)-(15)cangenerallybeselectedfromTable1[25-29].
InLS-DYNAexplosivematerialsaredescribedbytheblastingexplosivematerialequationandstateequation.
Whilemodelingisnotexplosivematerialsandequationofstate,intheformationoftheKfileafterthechangeintheKfile.
Thetypeofmaterialforexplosivesis(*MAT-HIGH-EXPLOSIVE-BURN),andthegeneralJWLHighExplosiveequationis:=1+1+.
(16)TheparametersintheformulacangenerallybeselectedfromTable2[26-29].
Airmaterialusing(*MAT_NULL),therearetwotypesofLS-DYNAequationofstatetodescribetheairmaterial.
Theequationofstate(EOSLINEAR-POLYNOMIAL)canbeexpressedasEq.
(17):17)TheparametersintheformulacangenerallybeselectedfromTable3[26].
Table1.
RockmechanicsparametersDensity(gcm-3)HardeningexponentModulusofelasticity(GPa)Poisson'sratioCompressivestrength(MPa)Tensilestrength(MPa)Failurestrain2.
630.
5280.
20170130.
6Table2.
Explosiveparametersselection(kg/m3)(m/s)(GPa)(GPa)125039004.
200.
453.
550.
160.
453.
151.
0Table3.
Airmaterialparameters(kg/m3)(MPa)(MPa)(J/m3)1.
250.
10000.
40.
402.
5*1051.
75*10-5Tampingplugmaterialusing(*MAT_PLASTIC),andthemechanicalparametersare:densityis1670kg/m3,elasticmodulusis2GPa,Poisson'sratiois0.
22.
LagrangeandALEaretwodifferentmethodsprovidedbyLS-DYNA3Dforsimulationoftheexplosion,thesetwomethodsareadoptedtosimulatetherelationshipbetweenexplosiveandblastingstructure.
InLagrange,elementconnectionofexplosivesandstructurecanbeestablishedthroughsharingnode.
InALE,explosiveisdefinedasfluid,itcouldavoidtheadverseeffectsofmeshdistortiononcalculationresultsintheexplosionprocess.
Decouplingchargeisadoptedintheresearch,Lagrangealgorithmisadoptedinrockandstemming,whiletheEuleralgorithmisadoptedinexplosiveandair,thegridcouplingofexplosive,airandsurroundingrockthroughcommanddefinition,thusnumericalsimulationoftheexplosionprocessisrealizedbyALEalgorithm.
1579.
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2.
ResultsThebuiltinANSYSmodelisderivedfromtheKfile.
InaccordancewiththeprovisionsoftableKfilesmodifiedmaterialparameters.
TheKfileintotheLS970solvertosolve.
Thecalculationofthestructureofthed3plotfileaftertheintroductionofLS-PREPOST1.
0processingsoftwareforprocessinganalysis.
ThesymmetricmodelwillbemirroredintoacompletestructuremodelusingreflectoperationwiththekeyMisc.
(Fig.
6).
a)=100usb)=120usc)=280usd)=400us1579.
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ISSN1392-8716e)=2100usf)=2200usFig.
6.
Stressstatecomparisonchartofperpendiculartothedirectionofblastinghole(left–nonemptycuttinghole,right–emptycuttinghole)Inordertoclearlyobservethestressconcentrationneartheemptyhole,thecrosssectionperpendiculartothefreesurfacemapwasusedforanalysis(Fig.
7).
4.
FieldexperimentThereconstructionprojectofHengyuancoalmineis9kminwidthfromeasttowest,7kminwidthfromnorthtosouth,andtheareaisabout46.
09km2.
TheprojectislocatedinthenorthwestofLiuqiaoTown,SuixiCounty,HuaibeiCity,whichis8kmawayfromHuaibeicityintheeast,isneighboredHenanprovinceinthewest,connectsshallowmineboundarybetweenNo.
1MineofLiuqiaoandHengyuancoalmineinthesouthandisclosedtolimitedboundaryofexplorationrightinthenorth.
Theprojectconstructstwoshafts,oneistheairshaftandtheotheroneisthereturnair.
Thedesignednetdiameterofreturnairshaftis7.
6mandfulldepthis993.
5m.
Freezingsinkingisconstructedfordesigntopsoilandfreezingbedrock,thebottomboundaryfreezingbedrockdepthis273.
5m,freezingdepthis315mandfreezingsegmentsupportingdepthis307m.
ThePermianbedrockShiqianfengfreezingzonecanbefoundwhenthecheckingholesthroughtheCenozoiclooselayergroup,generallyfreezingdepthisabout22.
70m.
Accordingtotheexplorationdata,thereisafaultjudgedasF17normalfaults,tendencyisthenortheastandnorthwest,inclinationis70°,dropis30-70m,extendedover4.
6kmlongnorthwestsideabout50mawayfromthewellboredepartment.
Inaddition,thefaultisreliablefaultofdrillholeandthree-dimensionalseismictomographycontrol.
Accordingtothemeasureddata,thedeepwellssmoothblastingtestsectionismainlysandstonelithologywhendrivingnorth,andsandstonerocksolidcoefficientis12to18,denseandhard.
Accordingtotheory,combinedwithon-siteconstructionconditionsandrockproperties,thehardrockofthenorthfreezingsegmentperformedwellblastingparametersaredesigned(Fig.
8andTable4(a-b)).
ThecombinedeffectofblastingstatisticsisshowninTable5.
TherockcrushingcircumstancessurroundingtheeyesideandtheeyemarksafterblastingareshowninFig.
9(a)and(b),respectively.
1579.
HARDROCKDEEPHOLECUTTINGBLASTINGTECHNOLOGYINVERTICALSHAFTFREEZINGBEDROCKSECTIONCONSTRUCTION.
ZHITAOZHENG,YINGXU,JIANGHUIDONG,QIZONG,LIPINGWANGJVEINTERNATIONALLTD.
JOURNALOFVIBROENGINEERING.
MAY2015,VOLUME17,ISSUE3.
ISSN1392-87161115a)=120usb)=200usc)=240usFig.
7.
Stressstatecomparisonchartofparalleltothedirectionofblastinghole(left–nonemptycuttinghole,right–emptycuttinghole)Table4a.
BlastingparametertableCircleNo.
BlastholeHoleNo.
Pre-circleBlast-holenumberBlastholeangle()Blastholedepth(m)BlastholelocationHolespace(mm)Circlediameter(mm)1Cuttinghole11-66905.
3085017002Cuttinghole27-1812905.
3065025003Brukupborehole119-3820905.
0071045004Brukupborehole239-6830905.
0068065005Peripheryhole69-11547875.
005107600Table4b.
BlastingparametertableCircleNo.
ExplosivechargeDetonatororderConnectionmodeSingleholeCircleholeCartridgenumberWeight(kg)CartridgenumberWeight(kg)175.
603628.
801Bundlecoupling264.
806048.
005384.
0014070.
007473.
5018090.
009542.
0014170.
5011Total307.
301579.
HARDROCKDEEPHOLECUTTINGBLASTINGTECHNOLOGYINVERTICALSHAFTFREEZINGBEDROCKSECTIONCONSTRUCTION.
ZHITAOZHENG,YINGXU,JIANGHUIDONG,QIZONG,LIPINGWANG1116JVEINTERNATIONALLTD.
JOURNALOFVIBROENGINEERING.
MAY2015,VOLUME17,ISSUE3.
ISSN1392-8716Fig.
8.
BlastingholearrangementdiagramTable5.
BlastingeffectcomparisonProjectnameUnitNonemptyholeEmptyhole(Φ=100mm)Excavatedsectionaream254.
1054.
10Propertiesofrockf12-1812-18Blastholedepthm5.
205.
20Efficiencyofborehole%89.
2093.
80Cyclicalfootagem4.
644.
88Circulatingblastingoffrockvolumem3216.
12218.
20a)Brokenrockb)PeripheryholeresidualporeFig.
9.
FieldexperimentalresultsFig.
10.
Emptyholeeffectivestresscomparison5.
DiscussionThefirstorderboreholeexplosiongeneratedstrongshockwave,whichwasoutwarddiffusioninconcentricway.
Simultaneously,shockwaveenergydecayedalsoveryfast,thescopeoftheshockwaveis~10-15timesoftheholediameter.
Stresswaveoftheadjacentblastholebegantooverlaywhen120us(Fig.
6(b)).
ItcanbeseenfromFig.
6(c)thatthecutwaynonemptyholesina280usmiddlecirclethestressonthefreesurfaceappearconcentration,thisisbecauseofthesixcuttingholestresssuperposition,themaximumstressis~230-263MPa.
Theemptyholecutin280usnearthefreesurfaceemptyholesappearstressconcentration,andthemaximumstressis~252-288MPa.
After400us,thefirststepgrooveeyestresssuperposition,andthenformsconcentriccirclesstresswavetransferoutward.
Fig.
6(e)-(f)isthetransferprocessofstresswavecausedbythesecondstepgrooveeye.
Inthesecondstepgrooveeye,theblastholeshockwaveattenuation,thenholestresswavesaresuperimposedoneachother.
Finallyconcentriccirclesstresswavewasformedandtransferredoutward.
ItcanbeseenfromFig.
7(a-c),afterthedetonationofthefirststepgrooveeye,afusiformstressareanearblastingholewasformed,thisisbecauseofthereverseinitiationofexplosivesfromdownsuccessiveinitiation.
About200us,stresswavereachesthecentercourt.
Ifthereisanonemptyholeinthecircle,eachholestresssuperpositionformationstressconcentration.
Andthemaximumstressconcentrationisabout260MPa,iftheblastingprocesscontainsalargeemptyhole,stressconcentrationneartheholeformedintheairatthetimeof240us,themaximumconcentrationofstressisabout640MPa.
012345670.
10.
150.
20.
250.
3Time(us)E+3Effectivestress(v-m)E-3SimulationFieldtest1579.
HARDROCKDEEPHOLECUTTINGBLASTINGTECHNOLOGYINVERTICALSHAFTFREEZINGBEDROCKSECTIONCONSTRUCTION.
ZHITAOZHENG,YINGXU,JIANGHUIDONG,QIZONG,LIPINGWANGJVEINTERNATIONALLTD.
JOURNALOFVIBROENGINEERING.
MAY2015,VOLUME17,ISSUE3.
ISSN1392-87161117Accordingtotheabovesimulationanalysis,itcanbefoundthatwhenthelargediameteremptyholewasused,thefirststepgrooveeyeinitiationcanproduceintheemptyholenearthestressconcentrationphenomenon,blastingwillappearafteracircleofreflectioncrackproducedbytheeffectofthereflectedtensilewaveintheairnearthehole.
Therefore,thelargediameteremptyholeinshaftindeepholeblastingcanimproveblastingquality,andreducesthegangueblockrate.
ItcanbeseenfromTable5,duringtheentiredrivingcycletestsectionandforthenoemptyhole,theaveragecyclefootageis4.
64m,theboreholeaverageutilizationrateis89.
20%.
Whilethelarge-diameteremptyholeoffootageis4.
88m,theboreholeaverageutilizationrateis93.
80%.
Thisshowsthattheuseofalargediameteremptyholecutblastingdeepboreholeutilizationwassignificantlyhigherthananon-emptyholeblastingmethodwhichcansignificantlyimprovethespeedofshaftconstruction.
FromtheFig.
9,fullfaceinrockcrushingandblastingblockareuniform,bulkrateisverylow,whichwillhelpgrabrockmachinerock,andprotectsthefreezingshaftpipeseffectively,suchasfreeze-fracturesecurityincidentswhenblastaroundtheeyesurfaceneat,duringthetrial,indicatingthatthelargediameterhollowboreholeblastingtechniqueforthefreezinghardrocksisfeasible.
Trialsofnon-emptyboreholesandemptyholewithadrilling25m,theapertureof100mm,werecarriedoutandcycledsixtimes.
ThefieldtestofanemptyholeconcentrationstresscontrasttothesituationisshowninFig.
10.
AccordingtoFig.
10,itcanbefoundthattheeffectivestressofthesimulationemptyholecoincideswiththecurveoffieldtestswithin300microseconds.
Accordingtofieldtrials,themaximumconcentrationstressofemptyholeisupto600MPa,similartotheresultsofthesimulation.
Thisshowsthatusethesetoflargediameteremptyholeintheholecutblasting,youcangetagoodcutblastingeffect.
6.
ConclusionLargediameteremptyholeblastinghassomecharacteristics,e.
g.
stressconcentrationandstressguidance,providefreesurfaceiscutblastingandreflectedtensionshockwavebreaksrock.
Inthisresearch,theresultsofANSYS/LS-DYNAnumericalsimulationsoftwareandfieldengineeringexperimentindicatedthatthemaximumstressnearlargediameteremptyholeismorethan600MPa.
However,ifwithoutlargediameteremptyholethemutualsuperpositionmaximumstressnearthecentercircleisjustabout300MPa.
Infreezinghardbedrocksectionverticalshaftconstruction,usinglargediameteremptyholeblastingtechnology,theaveragedrillingdepthis5.
20m,theaveragecycledrillinglengthis4.
88mandblast-holeutilizationratereached93.
80%,thebulkratedecreased.
Thus,thistechnologycanimprovethedrivingspeedoffrozenhardbedrockmineverticalshaftconstructiongreatly.
Inperipheralholes,smoothblastingtechnologyandairdeckingwereadoptedforavoidingover-breakandunder-break.
Meanwhile,multi-deckblastingtechnologywasusedtoreducesingle-sectionamountofblastingcartridgestoguaranteethesafetyoffreezingpipesandfreezingwall.
Therefore,thisresearchhasimportanttheoreticalsignificanceandapplicationvalueforkilometerdeepverticalshaftrapidexcavationandliningconstructionsafetyinfrozenhardbedrocksection.
AcknowledgementsThisresearchwasfoundedbytheNationalNaturalScienceFoundationofChina(No.
51374012,No.
51174004)andAnhuiProvinceScienceandTechnologyProject(No.
1501041123).
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ZhitaoZhengreceivedMasterdegreeinGeotechnicalEngineeringfromAnhuiUniversityofScienceandTechnology,Huainan,China,in2014.
Hiscurrentresearchinterestsincludemodernengineeringblastingtechnology,deepminesurroundingrocksupportandreinforcementtechnology.
YingXureceivedPh.
D.
degreeinEngineeringMechanicsfromUniversityofScienceandTechnologyofChina,Hefei,China,in2003.
NowheworksatAnhuiUniversityofScienceandTechnology.
Hiscurrentresearchinterestsincludemodernengineeringblastingtechnique,deepminesurroundingrocksupportandreinforcementtechnology.
JianghuiDongreceivedMasterEngineeringdegreefromLanzhouUniversityofTechnology,Lanzhou,China,in2003.
NowheworksinUniversityofSouthAustralia.
Hisresearchinterestsincludenonlinearandadaptivecontrol,finiteelementmodellingandanalysis,biomechanics,platebucklingbehaviorincompositestructure.
QiZongreceivedPh.
D.
degreeinEngineeringMechanicsfromUniversityofScienceandTechnologyofChina,Hefei,China,in2004.
NowheworksatAnhuiUniversityofScienceandTechnology.
Hiscurrentresearchinterestsincluderockbreakingtheoryandtechnology,controlblastingtechnology.
LipingWangreceivedM.
Eng.
degreeinMechanicalEngineeringfromTianjinUniversity,Tianjin,China.
NowsheworksinUniversityofSouthAustralia.
Herresearchinterestsincludemechanicaldesign,mechanicalprocessing,reverseengineering,biomechanicsandbiomaterials.