外文翻译-分析采场工作的液压支柱支撑

翻译AnalysisofsupportbyhydraulicpropsinalongwallworkingC.Gonzlez-Niciezaa,A.Menndez-Dazb,A.E.lvarez-Vigilc,M.I.lvarez-FernndezaaDepartmentofMiningEngineering,MiningEngineeringSchool,UniversityofOviedo,Independencia13,33004,Asturias,SpainbDepartmentofConstructionEngineeringandManufacturing,MiningEngineeringSchool,UniversityofOviedo,Independencia13,33004,Asturias,SpaincDepartmentofMathematics,MiningEngineeringSchool,UniversityofOviedo,Independencia13,33004,Asturias,SpainReceived24May2007;receivedinrevisedform27September2007;accepted4October2007Availableonline4November2007AbstractThispaperpresentsastudyofthesupportsysteminananthraciteworkingsituatedinFeixolin(NorthernSpain).Theworkingisminedbythelongwallmethod,cavingbeingcontrolledbymeansofhydraulicpropsandwoodencribs.Asthecoalseamhasanaveragethicknessof3.5mand30slope,theworkingsdonotmeetSpanishregulationsfortheminingoflongwallcoalseams.Thismeansthatthesupportsystemmustbestudiedandtestedbeforeitisdefinitivelyimplementedinthemine.Adetailedstudyofthematerialsthatmakeupthecoalseamandthesurroundingrockmasswascarriedout,determiningthegeomechanicalpropertiesofthesebymeansofbothlaboratoryandinsitutests.Tothisend,afullscaleexperimentalworkingwasconditionedtocarryoutthetests,withspecialemphasisontheloadplatetestsandpenetrationloadtestscarriedoutwiththeactualhydraulicsupportpropsoftheworking.Withthedatathusobtained,thebehaviouroftheworkingwasmodelledusingFLACinordertodeterminethemaximumpressurethatthecoalhangingwallandfootwalliscapableofsupporting,aswellasthedensityofthepropsandtheconditionsofthesupportstheyrestonsothatpenetrationofthepropsisnotproduced.Theoverallaimwastovalidatetheintendedsupportsystemfortheundergroundmine.2007ElsevierB.V.Allrightsreserved.Keywords:Longwallcoalfaces;Supportsystem;Hydraulicsupport;Fullscalelongwall;Hydraulicprops;Sleepers1.IntroductionandbackgroundIncoalmining,theimprovementofthemechaniza-tionofundergroundmines(workings),aswellasthepreparationwork(maincrosscuts,veindrifts,pits,etc.)hastraditionallybeenprecededbyaccumulatedknowledgeofsmall-scaleminingcarriedoutovermanyyears.However,whencoalseamsofmajorthicknessandslopeappear,itisnecessarytocarryoutamorethoroughstudyofthesupportsysteminthemine.Inthesecases,thegoalofanysupportsystemistoachieveequilibriumoftherockmass.Thesupportneededtoaccomplishthisobjectivedependsonthegroundreactioncurve.Theconceptofagroundreactioncurvewasoriginallydevelopedfortheciviltunnelingindustrywherethetimingandmethodofgroundsupportisdeterminedbymonitoringthesupportpressureandexcavationconvergenceduringconstruction(Brownetal.,1983;EsterhuizenandBarczak,2006).Thegroundresponseapproachhasfoundapplicationinbothhardrockandcoalminingasamethodtobetterunderstandtheinteractionbetweentherockmassandthesupportsystem(Bigby,1987;Vervoort,1988;BarczakandGearhart,1998;SinghandSingh,1999).Theadvancesmadeinnumericalmodeling(Coulthard,1999)providenewopportunitiestodevelopgroundreactioninformation.FinitedifferencesoftwaresuchasFLAC(FastLagrangianAnalysisofContinua)(Itasca,1996)canbeusedtodevelopmeaningfulgroundres-ponsecurves.Thesoftwareisabletorealisticallymodelrockbehaviourfromtheinitialelasticresponsetothelargedisplacementsanddeformationsthatareassociatedwithrockfailure.Thesoftwarealsohasabuilt-inprogramminglanguagewhichallowstheusertocontrolloadsanddisplacementsinthemodel.Byapplyinginternalpressuretotheentryexcavation,thegroundresponsecurvecanbedetermined.Oncethisisdone,moreappropriatedesigncriteriaforsupportcanbedeveloped(Badretal.,2002;MedhurstandReed,2005).Numericalmodellingthusconstitutesabasictoolfordesigningthesupportsysteminaminewhensituationsarisethatsubstantiallyalteritsconfiguration,suchastheneedtomineseamsofmajorthicknessandslope.ThisiswhatoccurredintheworkingsofSeamC-24attheFeixolinmineownedbyMSP(MineroSiderrgicadePonferrada).Thisseamhadpreviouslybeenminedasanopen-castmine.Environmental,socialandeconomicmotivesjustifiedtheneedtominethisseamasanundergroundmine.ThefirmMSPdecidedtodosobymeansofalongwallmeasuring180minlength,usinghydraulicpropsandwoodencribstocontrolthecavingoftheworkings.SeamC-24correspondstoagoodqualityanthracite,withanaveragethicknessof3.3mandaslopeof30situatedatadepthof300mbelowground.Duetoitsdimensionsandslope,thisseamdoesnotcorrespondtothedirectivesestablishedinSpanishregulationsforthesupportofcoalseams(ITCMIE,1996).ThismeansthataresearchprojectmustbedevelopedthatvalidatesthetechnicalfeasibilityoftheSupportSystemSchemeinthemine.Thispaperpresentsthemethodologyfollowedinthedevelopmentofthisresearchproject.ThelongwallcurrentlyundertestintheFeixolinminewasusedasanexperimentalworkingforinsitutestswiththeaimofdeterminingthegeotechnicalcharacteristicsofthehangingwall,footwallandsurroundingrockmassoftheseam,aswellasthoseofthehydraulicpropsandwoodencribs.ThisallowedustoobtainthenecessarydatatocarryoutnumericalmodellingofdifferentsupportsystemalternativesusingFLAC.WeshallfirstdescribetheareasoftheFeixolinminethatwerestudied(Section2)tothenproceedinSection3withadescriptionoftheexperimentallongwallthatwasdevelopedtocarryoutthisresearchstudy.Subsequently,weshallpresentadetaileddescriptionofthematerialsthatmakeupthecoalseamandthesurroundingrockmass(Section4).Section5describesthelaboratory(Section5.1)andinsitutests(Section5.2)conductedtodeterminethegeomechanicalpropertiesofeachmaterial.Specialreferenceismadetotheloadplateandpenetrationtestsoftheprops,sincetheweaknessofthefootwallindicatesthatthisisakeyissueinthedesignofthesupportsystem.InSection5.3,theelastoplasticconstantsaredeterminedforeachmaterialonthebasisofthetestscarriedout.InSection6,weanalyzetheresultsofthenumericalmodellingperformedusingFLACtodeterminethemaximumpressurethatthecoalhangingwallandfootwalliscapableofsupporting.Furthermore,thedensityofpropsiscalculated,aswellasthesupportconditionssothatpenetrationofthepropsisnotproduced.Finally,themostimportantaspectstobetakenintoaccountinthedesignofthesupportsystemfortheworkingsarepresentedintheconclusionssection.2.AreasstudiedintheFeixolinmineForthesakeofthestudy,theFeixolinminewasdividedintofourareas.Areas1,2and3areopen-cast,whiletheInteriorArea,locatedintheundergroundmine,correspondstotheexperimentalworkingusedtocarryouttheinsitutestsofthesupportsystem.Fig.1showsthegroundplanpositionofeachoftheareasunderstudy.Fig.2isaschematicABcross-sectionshowingthepositionofSeamC-24andthelocationoftheexperimentalworkingsintheInteriorAreaoftheundergroundmine.TheInteriorAreaconsistsofaworkingandtworockdriftstoSeamC-24fromthemaincrosscutsofLevel4(1300mabovesealevel)andofLevel6(1400mabovesealevel).Atthelowerend,theseamisaccessedfromthesurroundingrockatthebaselevel;whileattheupperend,arockdriftgivesaccesstotheseam(seeFig.4).Subsequentlyacrosscutwillbemadeintheseam,eliminatingthepreviousrockdriftstotheworking.Asthiscoaldriftadvances,itwillbeabandonedbehindthefaceandwillbereachedbycrosscutstothebulkdrift(Fig.3).Weshallnextdescribethefundamentalcharacter-isticsoftheexperimentallongwallworkinginwhichtheteststovalidatetheSupportSystemSchemeintheminewillbeconducted.Pig.1locationoftheareaunderstudyinthefeixolinminePig.2schematiccross-setionABoftheareaunderstudyinthefeixolinmine3.ExperimentallongwallworkingandproblemsinthesupportsystemTheworkinginwhichSeamC-24isminedisalongwallcoalfacewithanaverageslopeof30andanaveragethicknessof3.3m.Theinitiallengthoftheworkingwas180m,althoughadrivewasadvancedintheseamonthe6thLevelwhichhasenabledthetotallengthtobereducedtoaround150m.Materialisintroducedintotheworkingviathisnewdrift,abandoningthechutethatwasusedinitially.Thethicknessoftheseamvariesalongtheworking,beingaround3matthetopandmorethan5matthebottom.Greaterthicknessesofupto7mhavebeenobservedintheareaofthechute.Thethicknessdecreasesasthedistancefromthecoalfacetothefaultincreases,untilthicknessesoflessthan3m.Coalwinningiscarriedoutbymeansofpickhammersandthecoalistransportedintheworkingusingachainconveyorandtrays.AdvanceoftheworkingiscarriedoutbycontrolledcavingusingwoodencribsandhydraulicpropsmanufacturedbySalzgitter,typesEAM36andEA25,restingonwoodensleepersonthefootwallandwitharticulatedboltandwedgeframesets,type100,onthehangingwall.TheEAM36propshaveminimumandmaximumopeningsof2.5mand3.6m,respectively.TheEA25propshaveminimumandmaximumopeningsof1.485mand2.5m,respectively.Thesepropswereplacedformingameshwithaseparationof1.25m0.55mbetweenprops.Theformerdistancecorrespondstothedirectionofadvanceandthelattertotheparalleldirectiontothecoalface.Fig.4showstwosupportlanesintheworkingwiththreerowsofprops.Fig.5representsthedistributionofthepropsinthetwoareasoftheworking,oneclosetoLevel6inwhichthedistributionofwoodencribsandthelocationofthedifferentrowsofpropscanbeappreciated,andanotherareaclosetoLevel4inthetailgate.Onlytworowsofpropsappearinthelatterareaintheworking.Weshallnowbrieflydescribetheobservationsmadeintheexperimentalworkingwheninstallingthehydraulicpropsupportsystem.Thepressuremeasuredinthepropswhentheywereinstalledwas11MPa.Thereadingscarriedoutonedaylaterindicatedthatseveralpropshadlostbetween4and6MPa.Thislossinpressureisduetothepoorcompetenceofthefootwall,leadingtothesleeperssinkingintoitandtheconsequentlossinloadbearingcapacityoftheprops.Moreover,itisnotpossibletotightenthepropsagainsttheroof,whichmeansthattheynolongerworkactively.Thehangingwallbeginstosufferalterationsandtofracture,resultinginrockfallsontothepropsanddisplacementofthesupportinthedirectionofmaximumslopeandtowardsthegoaf.Afterthreedays,muchlowerworkingpressuresthantheinitialloadvalueof11MPawereappreciatedintheworking.63%ofthemeasuredpropsdidnotreachapressureof6MPaand29%wereevenbelow5MPa.Only27%ofthepropshadapressureofbetween6and11MPa,while10%hadahigherpressurethantheinitialloadvalue,11MPa.Ontheotherhand,someofthepropswereunder-minedduetothepresenceofwateratsomepointsonthelongwall.Thiswatereasilydegradesthecoalmudsituatedonthecoalfacefootwall,makingthiscoalmudflowplastically.Thishasmeantthatithasbeennecessarytoincreasethesupportsurfacefortheprops,protectingthefootwallwithwoodensleepersplacedonboards.Furthermore,theroofhasbeenlaggedwithwoodbetweentheframesetssoastopreventsmallblocksfromfalling.Theinitialideawastoplacewoodencribsevery20minthedirectionofadvance,althoughthesearecurrentlyonlyusedasprotectionintheaccessareastotheworking.ThecribsinthepartoftheworkingclosetothechutecanbeseeninFig.6-a,alongwiththetimberinginthisarea.Fromtheobservationscarriedoutduringtheremovalofthelastrowofprops,itwasfoundthattheroofgenerallycavesinwell,registeringgoafblockswithamaximumsizeofaround122m3.Thetailgateissupportedwithtrapezoidal290N/mdoublemetallicframesets(seeFig.6-b)withtheclampsandribs,alllaggedbehindwithtimber.Someframesetswarpedslightly,whileintheareaclosetothechutethepushisgreater,bendingsomeprofiles,underminingthemloseatthebottomandbreakingsomeoftheclamps.Topreventthesefailuresinthesupportsystem,itisnecessarytostudythestressstateoftheworkinganddeterminethemaximumpressurethatthecoalseamhangingwallandfootwallarecapableofsupporting.Todoso,itisessentialtogaindetailedknowledgeofthematerialsthatmakeuptherockmassofthemine,aswellasofthematerialsthatareemployedinthesupportsystem,suchasprops,woodencribsandsleepers.Weshallnowseehowtheseaspectswerestudied.4.GeologicalcharacterizationofthemineItwasinitiallynecessarytoconductadetailedanalysisofthelithologiesthatconstitutethehangingwallandfootwallofSeamC-24.Thisanalysis,whichtookplacebothinsidethemineandinAreas1,2and3oftheopen-castmine,consistedof:Astudyofthegeneralgeologyofthemine,aswellasofitshydrogeology.Visualinspectionofthematerialsinthehangingwallandfootwalloftheseam.GeotechnicalanalysisofthethreeareasidentifiedasAreas1,2and3,aswellasinthecrosscutofLevel4andinthegoafoftheworking.Measurementofthejointsanddiscontinuitiessoastocarryoutadetailedmappingofthese.Theaveragesizeoftheblockswasalsodetermined.Thedrillingofseveralboreholesof76mmindiameterinthetailgateoftheworking,withtheextractionofthecoreforgeotechnicalanalysisinthelaboratory.Weshallfirstdescribetheaspectsrelatedtothegeneralgeologyofthearea,tothengoontostudythelithologiesofthehangingwallandfootwallofSeamC-24inmoredetail.4.1.GeneralgeologyoftheareaTheanthracitecoalseamC-24oftheFeixolingroupbelongstothecoalbasinofVillablino,thegeologicalenvironmentofwhichisfundamentallymadeupofpreCambrianandPalaeolithicmaterials.ThediscordantStephanianconstitutestheVillablinocoalbasin,andismadeupofadetriticseriesthatispost-tectonicincharacter.Theconglomeratesarecomposedofwell-rounded,centimetricbouldersofquartz,sandstonesandslatesinasiliceousmatrix.Thesandstonesarelitharenites,sub-litharenites,sub-arkosesandquartzsandstonescementedbyironoxidesandchlorites.Theypossesserosivesedimentarystructures.Thecoalseamsarevariableinthickness,rangingfrom0.40to2m,reachingupto5minsomeexceptionalcases.Thetotalthicknessoftheseries,thoughvariable,rangesbetween2500and3000m.Porphyriesofupto30minthicknessappearatthebaseoftheseries,concordantwiththeseries.Theseproducedthermalmetamorphismonthesurroundinglevels,transformingthecoalintoanthracite.Fig.7showsthedistributionoflithologiesinthesurroundingsoftheFeixolinmine.Asregardsthehydrogeologyofthearea,twoverydistinctareasmaybeconsidered.Thepre-CambrianFig.7.GeologicalformationsinthesurroundingsoftheFeixolinarea.Fig.6.a)Thewoodcribsofthechuteandb)thedoublemetalframesetsofLevel4.72C.Gonzlez-Niciezaetal./InternationalJournalofCoalGeology74(2008)6792materialsaremainlymadeupofslateswithalmostnullpermeability,whichtranslatesasscantaccumulationandcirculationofundergroundwater.Thenorth-easternzoneisformedbyDevonianandCarboniferousground,presentingmajorinterestfortheformationofaquifers.Thelithologicaldifferencesbetweenformations,aswellasthetectonicswhichhasgivenrisetolargestructureswithhundredsofmetresoflimestones,aresealedbyimpermeableclayey-slateformations.Numerousspringsexistinthiszone.TheStephaniansystemalsopossessescharacteristicsthatallowwatertoaccumulate,aboveallthecoarserdetriticlevels.Althoughtheselevelsaredisconnectedfromoneanotherbynumerouslayersofimpermeableslates,theymaycommunicateasaresultofthepresenceoffaults.4.2.StratigraphyoftheareaclosetotheseamThelithologiesoftheareaclosetothecoalseamwerefirstobtainedfromthemaincrosscutsonLevels4and6,whichalloweddirectinspectionofthehangingwallandfootwallofthecoalseam.Several76mmdiameterboreholeswerealsodrilled,extractingthecoretocarryoutlaboratorytests.TheseamwascharacterizedindetailintheveindriftonLevel6atthemomentinwhichthecoalfacewasfirstcutonopeningupthechuteoftheworking.Fig.8showsthelithographiccross-sectionofthisface,inwhichdifferentlithologicalsectionscanbeappreciated.Inspectionworkwasmademoredifficultonthecrosscutsbythetimberlaggingbetweentheframesets,themetallicgrillesandthemetallicframesetsthemselves,which,apartfromhinderingvisualobservation,affectcompassmeasurements.Duetothesedifficultiesintakingmeasurementsinsidethemine,thestudywasextendedtotheopen-castoutcroppingofSeam24,inAreas1,2and3.Fig.9showsthedistributionofmaterialsinArea2.Thefollowingmaterialswerefoundinthehangingwalloftheseam:Siltstone:Thehangingwalladjoiningtheseamismadeupofsome23moffracturedlighttodarkgreyfine-grainedsiltstone,withanetworkofjointswithspacingsvaryingbetween15cmand1m.Atthesametime,themajorpresenceofcm-sizeplantfossilremains(leaves,trunks,etc.)isworthnoting,aswellascoaldeposits,moreabundantinpositionsclosertothecoalseam.Mudstone:Thesiltstoneisfollowedbya5-m-thicklayerofahighlyfracturedmaterial,whichwasdenominatedmudstone.Thisisamaterialwithatransitioncompositionbetweenmudandveryfinegrainsandstone.Themostimportantfamiliesofjointshavespacingsthatvarybetween0.4mand1m,thepossibleformationofblocksofupto1m1mbeingobserved.Greywackes:ThehangingwallofSeamC-24ismadeupofamediumgraingreywackewithanodularor“onion-like”appearance.This“onion-like”appearanceobeysthesingulardispositionoflayersthatarecentimetricalinthicknessesandofscantcompactionaroundasmall-sizedcentralnodule.Thisnodularconfigurationofthegreywackewouldfavourthecavingoftheworkingasthehydraulicpropsareremoved.Thefollowingmaterialswerefoundinthefootwalloftheseam:Shale:Thematerialsituatedimmediatelybelowthecoalseamismadeupof3090cmofgreyshale,withabundantplantremainsand,onoccasions,tracesofclay.Siltstone:Belowtheshaleisfounda50-cmthicklayerofsiltstone,whichisdarkgreyincolour,withlargeoxidationstainsandsimilarcharacteristicstothehangingwallsiltstone.Coal:Belowthesiltstone,thereisacoallayerofbetween30and50cminthickness,whosefootwallslidesrelativelyeasily,aswasobservedondifferentvisitstotheopen-castmine.Mudstone:Belowthecoallayeraretobefoundsome78mofmudstone,characterisedbypresentingoxidationstainsandmm-sizelensesofcoal.Onceagain,thisisatransitionmaterialbetweensiltstoneandsandstone.Onthebasisoftheselithologies,“coalmuds”measuringafewcentimetresinthicknessandcomposedofamixtureofcoal,clay,andshalewereidentifiedinthefootwall.Thesecoalmudsbehavelikeahighlyplasticmaterialandmightcauseproblemsofslidingintheworking,especiallyinthoseareaswithpoordrainage.Asregardsthecoal,thisismadeupofgoodqualityanthracitethatconstitutesthehangingwallveinandwhichdecreasesinqualityaswellasalternatingwithotherintermediateseamsofcoalmudandearthasitapproachesthefootwall.Thehangingwallveinis1-mthickandisfollowedbybetween70cmand1.2mofalternatingcoalmudandearth,withamixtureofbothcoalandcoalmudappearing.Thefootwallveincanbeidentifiednext,withathicknessofbetween0.5and1.3m.Beforereachingafirmfootwall,afinelayerofclaycoalmudisencountered,ofaround15cm.4.3.StudyofthejointsandsizeoftheblocksInordertocarryoutaninitialestimationofthestrengthcharacteristicsofthematerials(seeSection5.3)itisnecessarytoknowthedistributionofjointsintherockmass.Todoso,thejointspresentinthehangingwallandfootwalloftheseamwereidentifiedinthemaincrosscutsonLevels4and6aswellasintheopen-castmine.Thedirectionanddipofthesejointswasmeasured,aswellastheirspacing,persistence,opening,roughness,fillinganddegreeofmeteorization.AllthemeasurementswereinputtedintotheDIPSsoftwarepackage,withtheaimofidentifyingthemainfamiliesofjointsandgraphicallyrepresentingtheirmainplanes.Table1showsthemeanvaluesoforientationanddipofthefamiliesofdiscontinuitiesencounte