田陳煤礦1.5Mt-a新井設(shè)計(jì)-淺談深部巷道變形機(jī)理及支護(hù)技術(shù)

摘要本設(shè)計(jì)包括三個(gè)部分：一般部分、專題部分和翻譯部分。一般部分為田陳煤礦1.5Mt/a新井設(shè)計(jì)。田陳煤礦位于山東省滕州市管轄的滕南礦區(qū)境內(nèi)，交通便利。井田走向（東西）長(zhǎng)約3.7km，傾向（南北）長(zhǎng)約7.32km，總面積為27.15km2。主采煤層為3＃煤，煤層傾角為1.3~20.56，平均總厚度為5m。井田地質(zhì)條件較為簡(jiǎn)單。井田工業(yè)儲(chǔ)量為18040萬t，可采儲(chǔ)量為12776萬t。礦井設(shè)計(jì)生產(chǎn)能力為1.5Mt/a。礦井服務(wù)年限為60.8a，涌水量不大，礦井正常涌水量為373m3/h，最大涌水量為400m3/h。礦井瓦斯相對(duì)涌出量為1.33m3/t，絕對(duì)涌出量為2.0m3/min，為低瓦斯礦井。井田開拓方式為立井單水平上下山開拓。采用膠帶輸送機(jī)運(yùn)煤，采用礦車進(jìn)行輔助運(yùn)輸。礦井采用兩翼對(duì)角式通風(fēng)方式。礦井年工作日為330d，工作制度為“三八”制。一般部分共包括10章：1、礦區(qū)概述與地質(zhì)特征；2、井田境界和儲(chǔ)量；3、礦井工作制度、設(shè)計(jì)生產(chǎn)能力及服務(wù)年限；4、井田開拓；5、準(zhǔn)備方式——帶區(qū)巷道布置；6、采煤方法；7、井下運(yùn)輸；8、礦井提升；9、礦井通風(fēng)與安全；10、設(shè)計(jì)礦井基本技術(shù)經(jīng)濟(jì)指標(biāo)。專題部分題目是淺談深部巷道變形機(jī)理及支護(hù)技術(shù)，主要是分析了深部軟巖巷道的變形機(jī)理及支護(hù)技術(shù)的探究，對(duì)深部圍巖支護(hù)原理做了較深刻的探究。翻譯部分主要內(nèi)容是關(guān)于伽馬射線傳感儀在煤礦殘頂煤厚度測(cè)量中的應(yīng)用，英文題目為：RemnantRoofCoalThicknessMeasurementwithPassiveGammaRayInstrumentsinCoalMines關(guān)鍵詞：立井；單水平；帶區(qū)；兩翼對(duì)角式通風(fēng)

ABSTRACTThisdesignincludesthreeparts:thegeneralpart,thespecialsubjectpartandthetranslationpart.ThegeneralpartisanewdesignforTianchenmine.TianchenmineislocatedinXintaiwhichcomeswithinthejurisdictionofTengzhouinShandongprovince.Itisveryconvenienttogettothemineintermsofbothhighwayandrailway.Thelengthofthecoalfieldis3.7km,thewidthisabout7.32km，andthetotalareais27.15km2.Thefourthandthesixtharethemaincoalseams,anditsdipangleis1.3~20.56degree.Thethicknessofthemineisabout5.0minall.Thegeologicstructureofthiscoalfieldissimple.Therecoverablereservesofthecoalfieldare180.4milliontons,andtheminablereservesare127.76milliontons.Thedesignedproductivecapacityis1.5milliontonspercentyear,andtheservicelifeofthemineis60.8years.Thenormalflowofthemineis373m3perhourandthemaxflowofthemineis400m3perhour.Therelativeminegasgushis1.33m3/tandtheabsolutegushis2.0m3/min,soitisalowgasmine.Themineisasinglelevelintwoshaftstodevelop.TecentrallanewayusesBeltConveyortotransitcoal,andtrolleywagonsareusedforaccessorialtransportationintheroadway.Theventilatedwayofoppositeangleoftwowingwasused.The“three-eight”workingsystemisusedintheTianchenmine.Itproducesfor330daysayear.Thisdesignincludestenchapters:1.Anoutlineoftheminefieldgeology;2.Boundaryandthereservesofmine;3.Theservicelifeandworkingsystemofmine;4.developmentengineeringofcoalfield;5.Thelayoutofpanels;6.Themethodusedincoalmining;7.Undergroundtransportationofthemine;8.Theliftingofthemine;9.Theventilationandthesafetyoperationofthemine;10.Thebasiceconomicandtechnicalnormsofthedesignedmine.ThetopicofspecialsubjectpartsistheAnalysisofGob-sideEntryRetainingTechnologyinMechanizedMiningFace.Itmakesafullycomprehensivestatementofgob-sideentryretainingtechnologyinmechanizedminingface.TranslationpartisaboatPassiveGammaRayInstrumentswasusedinCoalMines.TheEnglishtitleis“RemnantRoofCoalThicknessMeasurementwithPassiveGammaRayInstrumentsinCoalMines”.Keywords:Shaft;Singlelevel;Panel;TwoWingOppositeAngleTypeWellVentilation.第頁英文原文RemnantRoofCoalThicknessMeasurementwithPassiveGammaRayInstrumentsinCoalMinesStephenL.BessingerandMichaelG.NelsonAbstruct:Currentundergroundminingpracticeoftenrequiresthatapredeterminedamountofcoalbeleftontheroofofthemined-outarea.Theneedtoleavesuchcoaloccursonbothcontinuousminerandlongwallsectionsisderivedfromconsiderationsofgroundcontrol,qualitycontrol,machineguidance,orsimplygoodoperatingpractice.Effortsatmeasuringboundarycoalthicknesshavebeenemployedmechanical,nucleonic,andenergyadsorptionandreflectionmethods.ThenucleonicmethodshavefoundapplicationinoperationsintheUnitedKingdom,theUnitedStates,theformerSovietUnion,andPoland.Naturalgammadevicesarecurrentlytheinstrumentofchoice,andseveralsuccessfulinstallationsexist.Thecalibrationofnaturalgammabackground(NGB)instrumentsmustbecarefullymaintained,andtheycannotbeusedinareaswhereaNGBradiationisnotpresent.Thisradiationisordinarilypresentinthefine-grainedsedimentaryrocksthatboundmanycoalseams.I.INTRODUCTIONModernundergroundcoalminingpracticeoftenincludesleavingcoalontheroofofthemineafterminingiscompleted.Roofcoalisoftenleftoncontinuousminersectionsforgroundcontrolpurposestopreventthefailureofanimmediateroofthatconsistsofweak,friablerock.Roofcoalmayalsobeleftinmineswhereconcentrationsofsulfurorasharehighernearthetopoftheseamtoreducetheconcentrationsoftheseimpuritiesinthesalableproduct.Controlofcoalqualityinthismannerisespeciallyadvantageousinmineswithlongwallsections,wherealargefractionoftheproductionoriginatesfromonegeneralareaoftheseam,makingblendingforqualitycontrolmoredifficult.Smallamountsofroofcoalmayalsobeleftforpurposesofmachineguidance.Thispracticeiscommoninapplicationswherethecoal-cuttingmachineistobeinanautomaticcontrolmode.LongwallfaceoperationinthismannerhasbeendemonstratedintheUnitedKingdom[1],[2],andsimilarsystemshavebeentestedintheUnitedStates[3],[4].Leavingameasuredamountofroofcoalinsuchapplicationsmakesitpossibletoguidetheshearingmachine,keepingitintheseam.Leavingbothroofandfloorcoalcanenhanceboththeperformanceandreliabilityofthecuttingmachinebyreducingitsexposuretothehighmechanicalstressthatisexperiencedwhencuttingtherockborderingtheseam.Thiscanincreasepicklifeandreducethewearonallpartsofthecuttingsystem[2],[5].Theneedtoleaveroofcoalleadsdirectlytotheneedformeasurementofthethicknessofthecoallayerleftontheroof.Manymethodsformakingthismeasurementhavebeeninvestigated.Manualmethods,includingdrillingandboreholeinspection,aretimeconsumingandoftenunreliable.Manyinstrumentalmethodshavebeeninvestigated,includingvibrationanalysis,pickforcesensing,ultrasonicandradardetection,andnucleonicmethods,butonlythenucleonicmethodshavebeenusedinactualproduction.TheresearchconductedbyCONSOLInc.onnucleonicmethodswillbedescribedinthispaper.Ⅱ.GAMMA-RAYBACKSCATTERSENSINGTheuseofgamma-raybackscattersensingformachineguidancewassuggestedasearlyas1958[6].AnactivenucleonicdeviceforcoalthicknessmeasurementwasproposedinGreatBritainin1961[7]anddesignedin1973[8],[9].Inthisdevice,asourceofgammaradiation(usuallycesium137oramericium247)isenclosedinahousingthatispositionednearthesurfacetobemeasured.Thegammaraysinteractwiththecoalandrock,andaresubjecttobothComptonscatteringandattenuation.Thebackscatteredraysaremeasuredbyagammadetector,andcoalthicknessiscalculatedfromacalibrationcurve.SeveraldesignsofthistypeofsensorweretestedinEngland,andacommercialmodelmanufacturedbyDowtywastestedbyCONSOLinWestVirginia.AprototypewasalsotestedbyNASAintheUSBMtestmineinBruceton,PA.Ineveryinstance,severalproblemswereencountered.Mostsignificantwasthevariableeffectoftheairgapbetweenthesensorandthecoalsurface.Becauseofthiseffect,sensorsweredesignedtooperateincontactwiththesurface,whichpresentedseveredifficultiesinactualminingoperations.Inaddition,withthelow-energygammaradiationemployed,coalthicknessesgreaterthan200-250mm(8-10in)couldnotbemeasured.Itwasalsofoundthatanyvariationofmaterialsintheboundarycoalortheimmediateroofcouldsignificantlybutunpredictablyalterthecalibration.Finally,thepresenceofanactiveradiationsourceinatypicalundergroundminingenvironmentraisedconcernsofsafetyandsourcecontrol.Becauseoftheseproblems,gammabackscattersensorshavebeengenerallyabandonedinfavorofotherdevices[11].Ⅲ.NATURALGAMMABACKGROUNDSENSINGDuringthetestingofvariousgammabackscattersensors,itwasobservedthatinmanycoalseams,theneighboringrockemitsa“natural”gammaradiation[12].Ithasbeenshownthatthisgammabackgroundresultsfromthepresenceoftracesofvariousradioactiveisotopesintherock.Thebackgroundisgenerallyhighinshale,lowerinsandstone,almostabsentinlimestone,andvirtuallyundetectableincoal.Radiationfromtheroofrockisattenuatedbyanycoalleftinplace,accordingtothewell-knownexponentialattenuationequation[13]:Whereattenuatedintensityincountspersecondμsourceintensityincountspersecondμattenuationcoefficientinreciprocalcentimetersthicknessofattenuatingmaterialincentimeters.IntensityIismeasuredbycountinggammarayemissionsinagiventime,andcoalthicknessmaybedeterminedfromtheattenuationequationusinganempiricallyderivedattenuationcoefficientμandknownbackgroundradiationIo.Althoughthegammabackgroundvarieswiththecompositionoftheborderingstrata,itisoftenveryconsistentoverwideareasinagivenmineorevenagivenseam.Theattenuationcoefficientofcoalisalsoreasonablyconstantbecausecarbonisbyfaritsmajorconstituent.Thegammabackgroundisessentiallyaplanarsource,andsincetheattenuationduetoairismuchlessthanthatduetocoal,thedistancefromthesensortotheroofisnotcritical.Inmostinstances,coalthicknessesupto500mm(20in)canbemeasured.WherethestrataborderingtheseamhasaNGB,thepassivegammasensorprovidesalltheadvantagesoftheactivegammadevicewithnoneoftheassociatedproblems.Forthesereasons,NGBsensorshavebecomethedeviceofchoice,particularlyinGreatBritain[2].TheyhavealsobeentestedsuccessfullyintheUnitedStatesinmanylocationssuchasinthePittsburghseaminbothPennsylvaniaandWestVirginiaandvariousseamsinKentucky,Illinois,Wyoming,andNewMexico[10],[14].Atypicalattenuationcurve,whichwasmeasuredinthePittsburghseam,isshowninFig.1.Fig.1.ExponentialattenuationcurveshownforNGB-1000instrument.ThreesignificantdifficultiesmayarisewiththeuseofaNGBsensor.First,thestrataborderingthecoalseammaynothaveagammabackground,orthebackgroundmaybetoolowtofacilitatemeaningfulmeasurements[15].Thisconditionmaybeminewide(forexample,inaminewithamassivesandstoneroof)ormayoccursporadically(fromsandchannels,“falseroofs,”orsimilarconditions).Inthefirstinstance,thesensorissimplyunusable;inthesecond,itmustbeusedjudiciouslywithfrequentchecksofbothcalibrationandaccuracy.Theseconddifficultythatmaybeencounteredisanintrinsicvariationinthegammabackgroundthatdoesnotresultfromsecondarydisturbances.Occurrenceofthisconditionisentirelysitespecificandmaybedeterminedonlybyfieldmeasurement.Itisalsoaccomodatedbyfrequentchecksoftheinstrument’scalibrationandaccuracy.Anunderstandingofthedepositionalgeologyoftheroofrockscanbeusefulinassessingtheprobabilityofthistypeofvariation.Thethirddifficultythatmustalwaysbedealtwitharisesintheprocessofderivinginformationfromradiologicalcountdata.Becauseradioactiveemissionisarandomprocess,theaccuracyofinformationderivedfromcountdataisdirectlyrelatedtothenumberofcountsrecorded[16].Thismeansthataveryaccuratecoalthicknessmeasurementrequireseitheraverylargedetectororaverylongcountingtimesothatineithercase,alargenumberofcountsmayberecorded[11].Ⅳ.INSTRUMENTTESTINGAvarietyofgammadetectorswereevaluatedinbothlaboratoryandundergroundtests.TwohundredtestholesweredrilledintheroofofaPittsburghseammine(hereknownasMineOne).Theroof-coalthicknessateachholewasdeterminedasaccuratelyaspossible,firstbyobservingdrillcuttingsandthenbyborescopeandfiberscopeinspection.Afteragivendetectorconfigurationwasfoundtoworksatisfactorilyinthelaboratory,itwastestedattheundergroundsitebyrecordingmultipleinstrumentreadingsateachtestholeandcomparingthesewiththeknowncoalthicknessatthatpoint.Fig.2.Correlationofthicknessreadings.Aninstrumentthathadaconsistentaccuracyof±25mmwastestedundergroundin1984.Thisinstrumentcomprisedaclusterofsevengammadetectors,whereeachwasa25-mm-diameter×50-mm-thicksodiumiodidescintillatorcoupledtoaphotmultipliertube.Readingsweretakenbyaveragingthecountsmeasuredbyeachdetectorina1-mintimeperiod.Thedetectorclusterwasshieldedby3.8mmofleadtoomitgammacountsoriginatingfromthefloorandrib(walls).Finaltestsoftheclustered-detectorinstrumentwereconductedinMineOnein1984todetermineitsaccuracywhenoperatingonamovingmachine.Atspeedsof2.5to3.0m/min,theaccuracywasstill±25mm.AdevelopmentalNGBinstrument(theNGB-1000)wasalsotestedin1984.TheNGB-1000coalthicknesssensor(aNASA-designeddevice)iscomprisedofasensingheadwithasinglescintillationcrystal(51×102×204mm)aphotomultipliertube,andacontrolpanel.Thecontrolpanelprovidescounts-to-thicknessconversion,selectablesamplingtime(5to20s),anddigitalthicknessdisplay.Thesensorislarge(228×228×610mm)and,becauseoftherequiredshielding,weighsalmost90kg.TheinstrumentisnowpermanentlyapprovedbytheMineSafetyHealthAdministration(MSHA)foruseinundergroundcoalmines.TestsattheMineOnetestsiteshowedthattheaccuracyoftheNGB-1000usinga20-ssamplingtimewascomparablewiththatoftheclustered-detectorinstrumentusinga60-ssampletime.Fig.2showscorrelationplotsforthereadingsoftheNGB-1000withtheroofcoalthicknessateachsiteasestimatedbyobservationwithaborescope.Becauseofthissuperiorperformance,itwasdecidedthattheNGB-1000wasthepreferableinstrumentformachineinstallationatanothermine(hereknownasMineTwo).V.OPERATINGINSTALLATIONTheNGB-1000wasinstalledonacontinuousminerinMineTwo.ThisWestVirginiaMineisalsointhePittsburghseam,anditsgammabackgroundlevelswerefoundtobealmostidenticaltothoseofthefirstmine.ConditionsatMineTworequirethat100to150mm(4-6in)ofcoalbeleftattheroofboundaryofcontinuousminerdevelopmentsections.Thisroofcoalisrequiredbecausetheshaleintheimmediateroofisfriableandweak.Inthepast,operatorshaveusedarockbandthatisusuallyvisiblenearthetopoftheseamasaguideinmaintainingthepropercuttinghorizon.However,thisisnotalwaysreliable.Earlierobservationshowedthattheactualthicknessofthecoalleftontheroofvariedwidely;further,itwasnotedthatoccasional,accidentalexcursionsintotheimmediateroofrequiredsupplementaryroofcontrolmeasuressuchasinstallationofplanksorcenterbolts.Thus,itwasconcludedthatoperatorsneededabettersourceofguidanceforcontrolofthecuttinghorizon,andaroofcoalthicknesssensorwasscheduledforinstallation.TheNGB-1000sensorwasinstalledonaJoy12CM10continuousminerinJuneof1988.Thesensingheadwasmountedonthecutterboomoftheminer,andthecontrolpanelwasmountedintheoperator'scab.Powerforthesensorwasinitiallyderivedfromanintrinsicallysafebatterypowersupply.Thisworkedwellforafewweeks,buteventuallysomebatterypowersuppliesweredischargedtoodeeplytoallowrecharging.Consequently,arequestwasfiledwithMSHAtoallowthesensortobepoweredthroughintrinsicsafetybarriersbyanelectronicpowersupplyconnectedtomachinepower.Thepermitwasgranted,andthesensorwasconnectedtomachinepower.Afterthesensorwasconnectedtomachinepower,theonlyoperatingproblemexperiencedwastheoccasionalfailureofcables.Asupplyoftherequiredcableswasmadeanddeliveredtotheminesothatdamagedcablescouldbequicklyreplaced.Muchofthecabledamagethatwasexperiencedcouldbeeliminatedbyslightmodificationstotheminerduringarebuild,allowingcablestobeinstalledinmoreprotectedlocations.Afterthesensorhadbeeninoperationforapproximatelytwomonths,asurveywasmadetodetermineitseffectonminingoperations.Ahand-heldgammadetectorwasusedtomeasureroof-coalthicknessin35locationsalongthetrackintheminingdevelopmentsection.ThemeasuredcoalthicknessesfromthesurveyareplottedinFig.3.ThepointatwhichtheNBG-1000wasinstalled(block51)showsclearly,asdoestheperiodinwhichthebatterypowersupplieswerenotworking,blocks52and53.AfurtherindicationoftheimprovementbroughtaboutbyinstallationoftheNGB-1000appearsinFig.4,whichshowsthepopulationvarianceamonggroupsofthreeroof-coalthicknesses,asmeasuredinthesurvey.Clearly,useofthesensorimprovestheconsistencywithwhichtheroofhorizoniscut.Fig.3.MeasuredcoalthicknessInadditiontotheimprovementinas-mined,roof-coalthicknesscontrol,anotherimprovementwasalsoobserved.Inthefirst57blocksofthetrackentry,itwasnotedthattheminerhadcutintotheimmediateroof27times,requiringcorrectiveaction.In13instances,centerboltingwasrequired;intheremaining14,plankswereinstalledwithoutcenterbolting.Inthenext14blocks,whichcomprisedthesurveyarea,onlyoneincidentofcuttingintotheroofwasobserved.Insevereroof-cutincidents,wherelargeareasofimmediateroofrockareexposed,additionalcostsmaybegeneratedwhenmoreextensiveremedialroofcontrolmeasuresarerequiredandwhenlargefallsoccurthatrequirecleanup,whichresultsinlostproduction.VI.DISCUSSIONTheNGB-1000wasreadilyadoptedbymineoperatorsasausefulaidtogoodminingpractice.Theuseofacoalthicknesssensorcanalsoresultinsignificantcostsavingsinasituationsuchasthatdescribedabove.Economicbenefitsderivedfromtheuseofacoalthicknesssensorresultfromfourfactors:1)Higherresourcerecoveryresultingfromclosercontroloftheamountofroofcoalleftaftermining2)lowerauxiliaryroofcontrolcostsresultingfromreducedincidenceofcuttingintotheroofrock3)higherproductivityresultingfromreducedtimespentinauxiliaryroofcontrol4)higherproductivityresultingfromareducedlevelofoperatoruncertaintyduringcuttingoftheroof.Fig.4.RoofcoalthicknessvarianceInconsultationwithminemanagementpersonnel,estimatesofcostsavingsderivedfromthesefactorsweremade.Usingthoseestimates,thenetpresentvalueforacoalthicknesssensoranditsinstallationonacontinuousminerwascalculatedbystandardmethods.Thosecalculationsshowedclearlythattheinstallationofthesensorwaseconomicallyadvantageous;thepay-outperiodwaslessthanoneyear.REFERENCES[1]D.Law,“Auto-steerage-Anaidtoproduction:Partone,”MiningEng.vol.148,no.328,pp.326-335,1988.[2]Anon,CoalFaceAutomation.Burton-on-Trent:NationalCoalBoard,MiningRes.DevelopmentEst.,1984,p.6.[3]T.J.FisherandE.R.Palowitch,“OverviewoftheDepartmentofEnergy’sprogramonthedevelopmentofautomatedmachineryforundergroundmining,”Proc.FourthCon$CoalMineElectrotechnol.(Morgantown,WV),Aug.2-4,1978,pp.33-11-33-15.[4]R.E.Pease,“AME’sLongwallautomationprogram,”unpublishedpaperpresentedatLongwallUSA,June19-22,1989,Pittsburgh,PA[5]A.E.Bennett,“Automaticsteeringofshearers,”MiningTechnol.,vol.55,no.631,pp.181-188,1973.[6]V.G.SegallinandA.A.Rudanovsky,“Stabilizationofmotioninsinkingandextractingmachinerywiththehelpofradioactivemethods,”AfomnayaEnergiyap.88,Jan.1958.[7]B.J.Greenland,“Radioactiveisotopemonitoring-Principleanduseinsteeringcoal-gettingmachines,”CollieryGuardian,vol.209,no.12,pp.684-688,1961.[8]P.A.Wood,“RemoteandautomaticcontrolofLongwallmining,”IEARep.ICTIS/TR19,IEACoalRes.,London,June1982,p.58.[9]V.M.Thomas,“Casestudy:Thedevelopmentofaninstrumenttomeasurecoalseamthickness,”inMeasurementforInstrumentationandControl(M.G.MylroiandG.Calvert,Eds.).London,PeterPeregrinus,1984,pp.251-279.[10]P.BroussardandW.B.Schmidt,“TheLongwallautomationresearchprojectoftheU.S.DepartmentofEnergy,”MiningTechnol.,vol.64,no.726,pp.138-143,1981.[11]J.S.Wykes,I.Adsley,L.R.Cooper,andG.M.Croke,“Naturalgammaradiation:Asteeringguideincoalseams,”In?.J.AppliedRadiationIsotopes,vol.34,no.1,pp.23-26,1983.[12]Anon,“Coalthicknessindicatorkeepsfacemachineoncurrenthorizon,”MiningJ.,vol.294,no.7656,p.505,1980.[13]W.H.Tait,RadiationDefecrion.London:Buttenvorths,1980.[14]M.J.PazuchanicsandE.R.Palowitch,“Coalinterfacesensorsforautomatedminingmachines,”inProc.FourthCon$CoalMineElectrotechnol.(Morgantown,WV),Aug.2-4,1978,pp.33-1-33-1t.[15]D.Hunter,“Computerizedshearingaidsoutput,”CoalAge,vol.62,no.8,pp.64-68,1983.[16]G.y.Knoll,RadiationDefectionandMeasurements.NewYork,1979.AuthorintroductionStephenL.BessingerreceivedtheB.S.andM.S.degreesinminingengineeringfromtheColoradoSchoolofMines.HeisalsoadoctoraldegreecandidateatWestVirginiaUniversityintheCollegeofMineralandEnergyResources.HeholdsProfessionalEngineeringRegistrationandvariousminingsupervisorycertifications.HeisaSeniorResearchEngineerattheConsolInc.ResearchandDevelopmentDepartment.HeisresponsibleforadvancedtechnologylongwallminingactivitieswithintheDepartment.MichaelG.NelsonreceivedtheB.S.degreeinmetallurgicalengineeringandanM.S.degreeinappliedphysics,bothfromtheUniversityofUtah.HereceivedthePh.D.degreeinmineralengineeringfromWestVirginiaUniversity.Hehasworkedextensivelyintheapplicationofmodemtechniquesofinstrumentationandcontrolinthemineralsindustries,andhasbeengrantedsevenpatentscoveringhisworkincontrolofcoalprocessingplants,instrumentation,andminingmachineautomation.HiscurrentresearchinterestsincludethephysicalandeconomicmodelingofpreciousmetalsrecoverysystemsandthereclamationoftailingsfromplacerminesandcyanideleachoperationsintheFarNorth.HeiscurrentlyassociateprofessorofminingengineeringintheSchoolofMineralEngineeringattheUniversityofAlaskainFairbanks.Hehas18yearsofexperienceinthemineralsindustries,includingworkincoppersmelting,steelmaking,zirconiumproduction,Coalmining,andgoldrecovery.HeispresidentofAlaskaMiningServices,inwhichcapacityhehasactedasaconsultanttoseveralindustrialclients.Dr.NelsonisamemberoftheSocietyforMining,Metallurgy,andExplorationandaseniormemberoftheInstrumentationSocietyofAmerica.HealsoservesontheboardofdirectorsoftheAlaskaMiners’Association.中文譯文伽馬射線傳感儀在煤礦殘頂煤厚度測(cè)量中的應(yīng)用StephenL.BessingerandMichaelG.Nelson摘要：當(dāng)前，地下煤層開采時(shí)，經(jīng)常需要在采空區(qū)留預(yù)定數(shù)量的煤對(duì)頂板進(jìn)行支撐。有必要在連續(xù)采煤機(jī)和長(zhǎng)壁工作面之間留下這些煤是來源于對(duì)于地面控制，質(zhì)量控制，機(jī)器指導(dǎo)，或是簡(jiǎn)單良好的實(shí)踐經(jīng)驗(yàn)的考慮。測(cè)量邊界煤層厚度方法的突破一直局限在機(jī)械、終止的核子、能源的吸附和反射的方法上。在英國(guó)、美國(guó)、前蘇聯(lián)和波蘭，核子的方法被發(fā)現(xiàn)應(yīng)用在手術(shù)中。自然伽瑪輻射傳感儀是目前的首選工具，并多次成功安裝使用。自然伽馬輻射（NGB）的校準(zhǔn)儀器必須精心維護(hù)，而且他們不能在一個(gè)不存在NGB輻射的領(lǐng)域使用。這種輻射通常存在于以細(xì)粒沉積巖為頂?shù)装宓拿簩又?。I前言現(xiàn)代地下煤炭開采往往留一部分煤對(duì)礦井頂板進(jìn)行支護(hù)當(dāng)?shù)V井煤炭開采完成后。頂煤往往留在連續(xù)采煤機(jī)的上部，是為了得到地面控制的目的，去阻礙由弱、易碎的巖石組成的直接頂垮落。在礦井巖孔、巖隙有較高濃度的硫和灰分時(shí)，頂煤也可能被留下，目的是去減少這些采出的煤中的雜質(zhì)。以這種方式對(duì)煤炭質(zhì)量進(jìn)行控制在長(zhǎng)壁采煤法中是非常有利的，特別是在有一大部分煤都是從裂隙、孔隙較發(fā)育的巖層附近采出時(shí)，這些煤炭和其他煤炭混合后，煤炭質(zhì)量的控制就變得更加困難。少量的頂煤也可以被留下來作為機(jī)器的導(dǎo)向。這種做法經(jīng)常應(yīng)用于采煤機(jī)的自動(dòng)控制模式。綜采工作面作業(yè)以這種方式已在英國(guó)證明[1]，[2]，以及類似的系統(tǒng)已經(jīng)在美國(guó)[3]，[4]測(cè)試。在這種情況下，留有一定數(shù)量的頂煤作為采煤機(jī)的導(dǎo)向，使采煤機(jī)在軌道上行駛成為可能。當(dāng)切割節(jié)理裂隙發(fā)育的巖層時(shí)，留下頂煤和底煤可以提高采煤機(jī)的性能和可靠性，主要是通過減少采煤機(jī)暴露在高的機(jī)械應(yīng)力下。這樣可以增加采煤機(jī)滾筒截割頭的壽命，同時(shí)減少截割部其他部位的磨損[2]，[5]。留下頂煤的必要性直接導(dǎo)致需要測(cè)量留在頂板煤層的厚度。針對(duì)這種測(cè)量的許多方法已經(jīng)被調(diào)查過。手動(dòng)的方法，包括鉆井和井眼檢查，耗時(shí)長(zhǎng)而且往往不可靠。對(duì)許多儀器分析方法也進(jìn)行了研究，包括振動(dòng)分析，選擇力傳感，超聲波，雷達(dá)探測(cè)，和核子方法，但只有核子方法已在實(shí)際生產(chǎn)中使用。由康壽公司進(jìn)行核子方法的研究將在本文介紹。Ⅱ伽瑪射線散射傳感早在1958年[6]，伽瑪射線散射傳感就被建議作為機(jī)器向?qū)褂谩?961年在英國(guó)[7]，測(cè)量煤層厚度的一個(gè)活躍的終止的核子裝置被提出，并在1973年[8]，[9]被設(shè)計(jì)出來。在此元件中，伽瑪射線（通常是銫137或247）的一個(gè)來源被圍在一個(gè)住房，這個(gè)住房定位在地表附近被測(cè)量。伽瑪射線與煤巖相互作用，而且會(huì)發(fā)生康普頓散射和衰減。伽瑪射線散射后由一個(gè)伽瑪探測(cè)器進(jìn)行測(cè)量，煤層厚度從一個(gè)校準(zhǔn)曲線上計(jì)算得出。在英國(guó)，對(duì)這種類型傳感器的幾種設(shè)計(jì)進(jìn)行了測(cè)試，接著道蒂公司制造了一個(gè)商業(yè)模型，這個(gè)模型被西弗吉尼亞州的康壽公司進(jìn)行了測(cè)試。在布魯斯頓的美國(guó)礦業(yè)局，美國(guó)航空航天局對(duì)測(cè)試礦的一個(gè)原型也進(jìn)行了測(cè)試。在每種情況下都遭遇了幾個(gè)問題。最重要的是發(fā)現(xiàn)傳感器和煤的表面之間的氣隙變量影響。因?yàn)檫@個(gè)發(fā)現(xiàn)，傳感器被設(shè)計(jì)去操作接觸煤的表面，在實(shí)際采礦作業(yè)中，這件事被認(rèn)為是非常困難的。此外，隨著低能伽馬射線的使用，煤層厚度大于200-250mm（8-10英寸）時(shí)，不能被測(cè)量。同時(shí)也發(fā)現(xiàn)，邊界煤或者直接頂任何材料的改變，可以觀察到，但是不能預(yù)測(cè)它的改變，并進(jìn)行校準(zhǔn)。最后，在一個(gè)典型的地下開采環(huán)境中發(fā)現(xiàn)存在一個(gè)活躍的輻射源，它提高了安全的顧慮和對(duì)源碼的控制。因?yàn)檫@些原因，伽瑪散射傳感器已經(jīng)普遍放棄在其他設(shè)備中應(yīng)用[11]。Ⅲ自然伽馬輻射傳感在各種伽馬散射傳感器的試驗(yàn)過程中，觀察到在許多煤層相鄰巖石散發(fā)出一種“天然”的伽馬射線[12]。有證據(jù)表明，這種伽馬輻射導(dǎo)致在巖石里發(fā)現(xiàn)各種放射性同位素的痕跡。通常，這種輻射在頁巖中很高，在砂巖中較低，在石灰石中幾乎沒有，在煤中幾乎無法察覺到。頂板巖石是通過留下的煤進(jìn)行輻射，根據(jù)指數(shù)衰減方程[13]：式中：——衰減強(qiáng)度的計(jì)算，s；——源強(qiáng)度的計(jì)算，s；——衰減系數(shù)，cm；——衰減材料厚度，cm。衰減強(qiáng)度I0是在一個(gè)給定的時(shí)間內(nèi)通過計(jì)數(shù)伽馬射線的排放次數(shù)進(jìn)行測(cè)定的，衰減方程通過一個(gè)實(shí)證研究，可以推導(dǎo)出衰減系數(shù)μ和已知的伽馬輻射I0，同時(shí)煤層厚度也可能被確定。盡管伽馬輻射是隨著周邊地層組成的不同而變化的，但是在一個(gè)給定的礦井，甚至一個(gè)給定的煤層，它一般還是非常一致的。對(duì)煤的衰減系數(shù)也相當(dāng)穩(wěn)定，因?yàn)槠駷橹?，二氧化碳是它的主要組成部分。伽馬輻射實(shí)質(zhì)上是一種平面的源頭，它在空氣中衰減和在煤中衰減相比較非常小，所以測(cè)得從傳感器到頂板的距離并不準(zhǔn)確。在多數(shù)情況下，煤厚度達(dá)500mm（20英寸）可以被測(cè)量。煤層上覆巖層接壤的地方有一個(gè)自然伽馬輻射,被動(dòng)伽馬傳感器提供了主動(dòng)伽瑪裝置所具有的所有優(yōu)勢(shì)，并且還沒有主動(dòng)伽瑪裝置所具有的相關(guān)問題。由于這些原因，自然伽馬輻射傳感器已經(jīng)成為首選設(shè)備，特別是在英國(guó)[2]。在美國(guó)在許多的地點(diǎn)，他們也曾經(jīng)進(jìn)行了成功的測(cè)試，如在賓西法尼亞州和西維吉尼亞的匹茲堡縫中，以及在肯塔基，伊利諾斯州、懷俄明州、和新墨西哥州的各種縫中[10]，[14]。一個(gè)典型的衰減曲線，它是衡量在匹茲堡的孔隙，如圖1所示。圖1指數(shù)衰減曲線顯示的NGB-1000儀器隨著自然伽馬輻射傳感器的使用，出現(xiàn)了三個(gè)重大困難。第一，地層接壤的煤層也許沒有一個(gè)伽馬輻射，或者是伽馬輻射太低以至于不便于進(jìn)行有意義的測(cè)量[15]。這種情況可能很常見（例如，在有一個(gè)巨大的砂巖頂板的煤礦。），或者也可能很少見（伽馬輻射來至于泥沙，“偽頂”或者相似的條件）。首先，傳感器是無法很容易使用的；第二，必須通過頻繁的校準(zhǔn)傳感器來確保其準(zhǔn)確性，才能慎重地使用它。第二種可能遇到的困難是伽馬輻射中的一種內(nèi)在變化不是來至于次要干擾。發(fā)生這種情況是取決于整個(gè)站點(diǎn)具體的條件，也許只取決于通過現(xiàn)場(chǎng)實(shí)測(cè)。同時(shí)也包括經(jīng)常校準(zhǔn)儀器以保證其準(zhǔn)確性。沉積地質(zhì)學(xué)中對(duì)頂板巖石的理解在評(píng)估這種類型變異的可能性中可能會(huì)有用。第三個(gè)難題是必須始終處理在這一過程中產(chǎn)生的放射性計(jì)數(shù)的推導(dǎo)信息數(shù)據(jù)。因?yàn)楹溯椛涫且环N隨機(jī)過程，從統(tǒng)計(jì)數(shù)據(jù)中推導(dǎo)出的信息的準(zhǔn)確性與紀(jì)錄數(shù)據(jù)的數(shù)量直接相關(guān)[16]。這意味著，一個(gè)非常精確的煤層厚度的測(cè)量，不僅需要一個(gè)非常大的探測(cè)器，而且需要很長(zhǎng)的計(jì)算時(shí)間，以至于在這兩種情況下，大量的數(shù)據(jù)才可能被紀(jì)錄[11]。Ⅳ儀器測(cè)試各種各樣的伽瑪探測(cè)器在實(shí)驗(yàn)室進(jìn)行了評(píng)估和地下核試驗(yàn)。兩百年的測(cè)試孔在匹茲堡煤層礦井頂板上鉆（這里被稱為一個(gè)礦山）。在每個(gè)孔的頂煤厚度都被盡可能準(zhǔn)確地確定，首先通過觀察鉆屑，然后通過內(nèi)窺鏡在纖維內(nèi)檢查。一個(gè)給定的探測(cè)器配置后，發(fā)現(xiàn)在實(shí)驗(yàn)室工作令人滿意，它在地下被測(cè)試，通過記錄每個(gè)測(cè)試孔的多儀器讀數(shù)，然后拿這些數(shù)據(jù)和已知厚度的煤層在同一點(diǎn)上比較。圖2相關(guān)的厚度讀數(shù)在1984年，對(duì)精確度為±25的一種儀器在地下進(jìn)行了試驗(yàn)。該儀器由七個(gè)伽馬探測(cè)器組成，每個(gè)探測(cè)器都由直徑為25mm，厚度為50mm的碘化物閃爍器耦合到一個(gè)光電倍增器管上形成。數(shù)據(jù)是通過每個(gè)探測(cè)器在一分鐘內(nèi)的平均計(jì)數(shù)測(cè)量取得的。該探測(cè)器群被3.8mm的鉛屏蔽，導(dǎo)致伽馬計(jì)數(shù)器在底板和兩幫中獲得的數(shù)據(jù)減少了。1984年，群探測(cè)器的最終測(cè)試在一個(gè)礦井的移動(dòng)機(jī)器上操作以確定其準(zhǔn)確度。當(dāng)速度為2.5～3.0m/min，準(zhǔn)確度仍然為±25mm?？刂泼姘逄峁┯?jì)數(shù)厚度轉(zhuǎn)換，可選擇的采樣時(shí)間（5至20s）和數(shù)字顯示厚度。由于需要屏蔽，該傳感器比較大（228×228×610mm），重90kg。目前，該儀器是由礦山安全健康管理局（MSHA）永久批準(zhǔn)使用的，用于煤礦井下使用。該礦一個(gè)現(xiàn)場(chǎng)的測(cè)試表明，該NGB-1000使用20s采樣時(shí)間所測(cè)的數(shù)據(jù)的精確度可以與聚集探測(cè)器使用60s采樣時(shí)間測(cè)得的數(shù)據(jù)的準(zhǔn)確性相比，圖2表示NGB-1000通過內(nèi)窺鏡觀察估計(jì)出每個(gè)站點(diǎn)的頂煤厚度的讀數(shù)。由于這種優(yōu)越的性能，它是決定NGB-1000在另一個(gè)礦井作為安裝的機(jī)器中的最好工具（這里被稱為二礦）。Ⅴ安裝操作系統(tǒng)在二礦，NGB-1000是安裝在一個(gè)連續(xù)采煤機(jī)上。這個(gè)西弗吉尼亞州煤礦也是在匹茲堡縫，它的伽馬輻射水平被認(rèn)為與第一個(gè)礦山幾乎是相同的。二礦需要在連續(xù)采煤機(jī)滾筒上部的頂煤邊界留下100～150mm（4～6英寸）厚度的煤。因?yàn)橹苯禹攷r層的易碎和不穩(wěn)定性，這些頂煤是需要留下來的。在過去，操作者已經(jīng)用過煤層頂部的可見巖石幫作為適當(dāng)切割低煤的一個(gè)導(dǎo)向。但是，這并不總是可靠的。早期的研究表明，實(shí)際留下的頂煤的厚度是差別很大的，更進(jìn)一步的，也有人指出采煤機(jī)滾筒可能偶爾的割到直接頂，這就需要制定頂板控制措施，例如安裝木板和中心螺栓。因此，可以得出結(jié)論，操作者需要一個(gè)良好的指導(dǎo)來源去控制把頂煤割平整，所以一個(gè)煤層厚度傳感器就應(yīng)運(yùn)而生了。1988年6月，NGB-1000傳感器被安裝在一個(gè)型號(hào)為12CM10的連續(xù)采煤機(jī)上。傳感頭安裝在采煤機(jī)滾筒上，控制面板安裝在司機(jī)室。該傳感器的電源最初由一個(gè)本質(zhì)安全的電池進(jìn)行供電。前幾個(gè)星期，這些電池運(yùn)作良好，但是最終一些電池的電量供應(yīng)太低以至于不能再次進(jìn)行充電。最后，請(qǐng)求被提