摘要本設計包括三個部分：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新井設計。田陳煤礦位于山東省滕州市管轄的滕南礦區境內，交通便利。井田走向（東西）長約3.7km，傾向（南北）長約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。井田地質條件較為簡單。井田工業儲量為18040萬t，可采儲量為12776萬t。礦井設計生產能力為1.5Mt/a。礦井服務年限為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。礦井瓦斯相對涌出量為1.33m3/t，絕對涌出量為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。采用膠帶輸送機運煤，采用礦車進行輔助運輸。礦井采用兩翼對角式通風方式。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、礦區概述與地質特征；2、井田境界和儲量；3、礦井工作制度、設計生產能力及服務年限；4、井田開拓；5、準備方式——帶區巷道布置；6、采煤方法；7、井下運輸；8、礦井提升；9、礦井通風與安全；10、設計礦井基本技術經濟指標。專題部分題目是淺談深部巷道變形機理及支護技術，主要是分析了深部軟巖巷道的變形機理及支護技術的探究，對深部圍巖支護原理做了較深刻的探究。翻譯部分主要內容是關于伽馬射線傳感儀在煤礦殘頂煤厚度測量中的應用，英文題目為：RemnantRoofCoalThicknessMeasurementwithPassiveGammaRayInstrumentsinCoalMines關鍵詞：立井；單水平；帶區；兩翼對角式通風

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量中的應用StephenL.BessingerandMichaelG.Nelson摘要：當前，地下煤層開采時，經常需要在采空區留預定數量的煤對頂板進行支撐。有必要在連續采煤機和長壁工作面之間留下這些煤是來源于對于地面控制，質量控制，機器指導，或是簡單良好的實踐經驗的考慮。測量邊界煤層厚度方法的突破一直局限在機械、終止的核子、能源的吸附和反射的方法上。在英國、美國、前蘇聯和波蘭，核子的方法被發現應用在手術中。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）的校準儀器必須精心維護，而且他們不能在一個不存在NGB輻射的領域使用。這種輻射通常存在于以細粒沉積巖為頂底板的煤層中。I前言現代地下煤炭開采往往留一部分煤對礦井頂板進行支護當礦井煤炭開采完成后。頂煤往往留在連續采煤機的上部，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，頂煤也可能被留下，目的是去減少這些采出的煤中的雜質。以這種方式對煤炭質量進行控制在長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、孔隙較發育的巖層附近采出時，這些煤炭和其他煤炭混合后，煤炭質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器的導向。這種做法經常應用于采煤機的自動控制模式。綜采工作面作業以這種方式已在英國證明[1]，[2]，以及類似的系統已經在美國[3]，[4]測試。在這種情況下，留有一定數量的頂煤作為采煤機的導向，使采煤機在軌道上行駛成為可能。當切割節理裂隙發育的巖層時，留下頂煤和底煤可以提高采煤機的性能和可靠性，主要是通過減少采煤機暴露在高的機械應力下。這樣可以增加采煤機滾筒截割頭的壽命，同時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致需要測量留在頂板煤層的厚度。針對這種測量的許多方法已經被調查過。手動的方法，包括鉆井和井眼檢查，耗時長而且往往不可靠。對許多儀器分析方法也進行了研究，包括振動分析，選擇力傳感，超聲波，雷達探測，和核子方法，但只有核子方法已在實際生產中使用。由康壽公司進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器向導使用。1961年在英國[7]，測量煤層厚度的一個活躍的終止的核子裝置被提出，并在1973年[8]，[9]被設計出來。在此元件中，伽瑪射線（通常是銫137或247）的一個來源被圍在一個住房，這個住房定位在地表附近被測量。伽瑪射線與煤巖相互作用，而且會發生康普頓散射和衰減。伽瑪射線散射后由一個伽瑪探測器進行測量，煤層厚度從一個校準曲線上計算得出。在英國，對這種類型傳感器的幾種設計進行了測試，接著道蒂公司制造了一個商業模型，這個模型被西弗吉尼亞州的康壽公司進行了測試。在布魯斯頓的美國礦業局，美國航空航天局對測試礦的一個原型也進行了測試。在每種情況下都遭遇了幾個問題。最重要的是發現傳感器和煤的表面之間的氣隙變量影響。因為這個發現，傳感器被設計去操作接觸煤的表面，在實際采礦作業中，這件事被認為是非常困難的。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，不能被測量。同時也發現，邊界煤或者直接頂任何材料的改變，可以觀察到，但是不能預測它的改變，并進行校準。最后，在一個典型的地下開采環境中發現存在一個活躍的輻射源，它提高了安全的顧慮和對源碼的控制。因為這些原因，伽瑪散射傳感器已經普遍放棄在其他設備中應用[11]。Ⅲ自然伽馬輻射傳感在各種伽馬散射傳感器的試驗過程中，觀察到在許多煤層相鄰巖石散發出一種“天然”的伽馬射線[12]。有證據表明，這種伽馬輻射導致在巖石里發現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行輻射，根據指數衰減方程[13]：式中：——衰減強度的計算，s；——源強度的計算，s；——衰減系數，cm；——衰減材料厚度，cm。衰減強度I0是在一個給定的時間內通過計數伽馬射線的排放次數進行測定的，衰減方程通過一個實證研究，可以推導出衰減系數μ和已知的伽馬輻射I0，同時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，但是在一個給定的礦井，甚至一個給定的煤層，它一般還是非常一致的。對煤的衰減系數也相當穩定，因為迄今為止，二氧化碳是它的主要組成部分。伽馬輻射實質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，所以測得從傳感器到頂板的距離并不準確。在多數情況下，煤厚度達500mm（20英寸）可以被測量。煤層上覆巖層接壤的地方有一個自然伽馬輻射,被動伽馬傳感器提供了主動伽瑪裝置所具有的所有優勢，并且還沒有主動伽瑪裝置所具有的相關問題。由于這些原因，自然伽馬輻射傳感器已經成為首選設備，特別是在英國[2]。在美國在許多的地點，他們也曾經進行了成功的測試，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，出現了三個重大困難。第一，地層接壤的煤層也許沒有一個伽馬輻射，或者是伽馬輻射太低以至于不便于進行有意義的測量[15]。這種情況可能很常見（例如，在有一個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傳感器來確保其準確性，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在變化不是來至于次要干擾。發生這種情況是取決于整個站點具體的條件，也許只取決于通過現場實測。同時也包括經常校準儀器以保證其準確性。沉積地質學中對頂板巖石的理解在評估這種類型變異的可能性中可能會有用。第三個難題是必須始終處理在這一過程中產生的放射性計數的推導信息數據。因為核輻射是一種隨機過程，從統計數據中推導出的信息的準確性與紀錄數據的數量直接相關[16]。這意味著，一個非常精確的煤層厚度的測量，不僅需要一個非常大的探測器，而且需要很長的計算時間，以至于在這兩種情況下，大量的數據才可能被紀錄[11]。Ⅳ儀器測試各種各樣的伽瑪探測器在實驗室進行了評估和地下核試驗。兩百年的測試孔在匹茲堡煤層礦井頂板上鉆（這里被稱為一個礦山）。在每個孔的頂煤厚度都被盡可能準確地確定，首先通過觀察鉆屑，然后通過內窺鏡在纖維內檢查。一個給定的探測器配置后，發現在實驗室工作令人滿意，它在地下被測試，通過記錄每個測試孔的多儀器讀數，然后拿這些數據和已知厚度的煤層在同一點上比較。圖2相關的厚度讀數在1984年，對精確度為±25的一種儀器在地下進行了試驗。該儀器由七個伽馬探測器組成，每個探測器都由直徑為25mm，厚度為50mm的碘化物閃爍器耦合到一個光電倍增器管上形成。數據是通過每個探測器在一分鐘內的平均計數測量取得的。該探測器群被3.8mm的鉛屏蔽，導致伽馬計數器在底板和兩幫中獲得的數據減少了。1984年，群探測器的最終測試在一個礦井的移動機器上操作以確定其準確度。當速度為2.5～3.0m/min，準確度仍然為±25mm。控制面板提供計數厚度轉換，可選擇的采樣時間（5至20s）和數字顯示厚度。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）永久批準使用的，用于煤礦井下使用。該礦一個現場的測試表明，該NGB-1000使用20s采樣時間所測的數據的精確度可以與聚集探測器使用60s采樣時間測得的數據的準確性相比，圖2表示NGB-1000通過內窺鏡觀察估計出每個站點的頂煤厚度的讀數。由于這種優越的性能，它是決定NGB-1000在另一個礦井作為安裝的機器中的最好工具（這里被稱為二礦）。Ⅴ安裝操作系統在二礦，NGB-1000是安裝在一個連續采煤機上。這個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為與第一個礦山幾乎是相同的。二礦需要在連續采煤機滾筒上部的頂煤邊界留下100～150mm（4～6英寸）厚度的煤。因為直接頂巖層的易碎和不穩定性，這些頂煤是需要留下來的。在過去，操作者已經用過煤層頂部的可見巖石幫作為適當切割低煤的一個導向。但是，這并不總是可靠的。早期的研究表明，實際留下的頂煤的厚度是差別很大的，更進一步的，也有人指出采煤機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，可以得出結論，操作者需要一個良好的指導來源去控制把頂煤割平整，所以一個煤層厚度傳感器就應運而生了。1988年6月，NGB-1000傳感器被安裝在一個型號為12CM10的連續采煤機上。傳感頭安裝在采煤機滾筒上，控制面板安裝在司機室。該傳感器的電源最初由一個本質安全的電池進行供電。前幾個星期，這些電池運作良好，但是最終一些電池的電量供應太低以至于不能再次進行充電。最后，請求被提