本科生畢業(yè)設(shè)計(jì)（論文）題目：朱集煤礦0.9Mt/a新井設(shè)計(jì) 煤礦井下無軌膠輪車的運(yùn)用現(xiàn)狀及發(fā)展趨勢(shì)摘要一般部分針對(duì)淮南朱集礦井進(jìn)行了井型為0.9Mt/a的新井設(shè)計(jì)。朱集礦井位于安徽省淮南市境內(nèi)，井田走向長(zhǎng)約7.0km，傾向長(zhǎng)約3.0km，面積約21km2。主采煤層為13-1#煤層，平均傾角2~5°，平均厚度4m。井田工業(yè)儲(chǔ)量為113.12Mt，可采儲(chǔ)量53.09Mt，礦井服務(wù)年限為42.1a。礦井正常涌水量為342m3/h，最大涌水量為462m3/h；礦井相對(duì)瓦斯涌出量為10.3m3/t，屬高瓦斯礦井。根據(jù)井田地質(zhì)條件，設(shè)計(jì)采用雙立井單水平開拓方式，井田采用全帶區(qū)式布置方式，共劃分為八個(gè)帶區(qū)，兩個(gè)盤區(qū)，軌道大巷、膠帶機(jī)大巷和回風(fēng)大巷皆為巖石大巷，布置在13-1#煤層底板巖層中。考慮到本礦井為高瓦斯礦井，礦井通風(fēng)方式采用兩翼對(duì)角式通風(fēng)，并在開采前預(yù)掘底板瓦斯抽排巷進(jìn)行瓦斯提前卸壓抽放。針對(duì)東一帶區(qū)采用了帶區(qū)準(zhǔn)備方式，共劃分7個(gè)分帶工作面，并進(jìn)行了運(yùn)煤、通風(fēng)、運(yùn)料、排矸、供電系統(tǒng)設(shè)計(jì)。針對(duì)13101工作面進(jìn)行了采煤工藝設(shè)計(jì)。該工作面煤層平均厚度為4.0m，平均傾角3°，直接頂為泥巖，老頂為細(xì)砂巖。工作面采用長(zhǎng)壁綜采一次采全高采煤法。采用雙滾筒采煤機(jī)割煤，往返一次割兩刀。采用“三八制”工作制度，兩班半生產(chǎn)，半班檢修，截深0.8m，每天5個(gè)循環(huán)，循環(huán)進(jìn)尺4.0m，月推進(jìn)度120m。大巷采用膠帶輸送機(jī)運(yùn)煤，輔助運(yùn)輸采用蓄電池式電機(jī)車牽引固定箱式礦車。主井采用兩套帶平衡錘的16t箕斗提煤，副井采用一對(duì)1.5t礦車雙層四車窄罐籠和一個(gè)帶平衡錘的1.5t礦車雙層四車寬罐籠運(yùn)料和升降人員。專題部分題目為《國(guó)內(nèi)外無軌膠輪車的運(yùn)用現(xiàn)狀及發(fā)展趨勢(shì)》，結(jié)合在神東礦區(qū)、濟(jì)三礦的運(yùn)用，介紹了無軌膠輪車的性能特點(diǎn)，運(yùn)用現(xiàn)狀，主要車型，以及國(guó)產(chǎn)化進(jìn)程，最后展望無軌膠輪車的發(fā)展趨勢(shì)。翻譯部分題目為《Anewcoalpillarsdesignmethodinordertoenhancesafetyoftheretreatmininginroomandpillarsmines》，主要介紹了一種在利用房柱式開采時(shí)，可以提高煤柱安全性的煤柱設(shè)計(jì)方法。關(guān)鍵詞：朱集煤礦；雙立井；帶區(qū)布置；兩翼對(duì)角式；綜采；沿空留巷；無軌膠輪車ABSTRACTThegeneraldesignisabouta0.9Mt/anewundergroundminedesignofZhujicoalmine.ZhujicoalmineislocatedinHuainan,Anhuiprovince.It’sabout7.0kmonthestrikeand3.2kmonthedip,withthe21.0km2totalhorizontalarea.Theminablecoalseamis13-1#withanaveragethicknessof4.0mandanaveragedipof3°.Theprovedreservesofthiscoalmineare113.12Mtandtheminablereservesare53.09Mt,withaminelifeof42.1a.Thenormalmineinflowis342m3/handthemaximummineinflowis462m3/h.Theminegasemissionrateis10.3m3/t,whichcanberecognizedashighgasmine.Basedonthegeologicalconditionofthemine,thisdesignusesaduel-verticalshaftsingle-leveldevelopmentmethod,andfullstrippreparation,whichdividedintoeightbandsandtwodistricts,andtrackroadway,beltconveyorroadwayandreturnairwayareallrockroadways,arrangedinthefloorrockof13-1#coalseam.Takingintoaccountofthehighgasemission,mineventilationmethodusetwodiagonalwingsventilation,andexcavesbottomgasdrainageroadwaybeforeminingtoreliefgaspressureinadvance.ThedesignappliesstrippreparationagainstthefirstbandofEastOnewhichdividedinto5stirpstotally,andconductedcoalconveyance,ventilation,gangueconveyanceandelectricitydesigning.Thedesignconductedcoalminingtechnologydesignagainstthe13101face.Thecoalseamaveragethicknessofthisworkingfaceis4.0mandtheaveragedipis3°,theimmediateroofismudstoneandthemainroofissandstone.Theworkingfaceappliesfullymechanizedlongwallfull-heightcoalcavingmethod,andusesdoubledrumshearercuttingcoalwhichcutstwiceeachworkingcycle."Three-Eight"workingsystemhasbeenusedinthisdesignandthedepth-webis0.8mwithfiveworkingcyclesperday,andtheadvanceofaworkingcycleis4.0mandtheadvanceis120mpermonth.Mainroadwaymakesuseofbeltconveyortotransportcoalresource,andbatterylocomotivetobeassistanttransport.Themainshaftusesdouble16tskipstoliftcoalwithabalancehammerandtheauxiliaryshaftusesatwinsnarrow1.5tfour-cardouble-deckcageandawide1.5tfour-cardouble-deckcagetoliftmaterialandpersonneltransportation.Theprojectsectionon"theuseofthetracklessrubber_tyredcarathomeandabroadpresentsituationanddevelopingtrend",IncombinationwiththeapplicationinShenDongminingarea,JiSanMine,thispaperintroducestheperformancecharacteristicsoftracklessrubber_tyredcar,usingsituation,mainmodels,andthelocalizationprocessandthefuturedevelopmenttrendoftracklessrubber_tyredcar.Thetitleofthetranslatedacademicpaperis"Anewcoalpillarsdesignmethodinordertoenhancesafetyoftheretreatmininginroomandpillarsmines".Mainlyintroducesanewtypeofroomandpillarmining,canimprovethesafetyofcoalpillarcoalpillardesignmethod.Keywords:Zhujicoalmine;doubleverticalshaft;bandmode;twodiagonalwingsventilation;comprehensivemechanizedmining;gob-sideentryretaining;tracklessrubber_tyredcar 第頁(yè)英文原文AnewcoalpillarsdesignmethodinordertoenhancesafetyoftheretreatmininginroomandpillarsminesE.Ghasemi*,K.ShahriarDepartmentofMiningofandMetallurgicalEngineering,AmirkabirUniversityofTechnology,Tehran,IranAbstract:Mostoftheproposedmethodsofcoalpillardesigndeterminepillardimensionsusingpillarestimationonlythroughthetributaryareatheory.Designingpillarbasedonthesemethodsisnotappropriateinroomandpillarmineswithpillarrecoverybecauseretreatminingandgobcreationgenerateabutmentloads.Neglectingabutmentloadsindesignstagemayleadtopillarfailureanddestructiveeffectsduringretreatmining.Thusproperpillardesignhasaremarkableeffectonminingeffectonminingsafety.Inthispaper,astep-bu-stepmethodispresentedtodesignpillarswithsquareshapeinroomandpillarmineswithregardtoexistingpillarsintheactiveminingzone(AMZ)andestimatingabutmentloadsaccordingtoexperiment-method.ThismethodhasbeenappliedtodetermineoptimumpillardimensionsinthemainpanelofTabasCentalMine(TCM),locatedinthemid-easternpartofIran.Obtainedresultsshowtheabutmentloadsaccountfor27%ofthetotalloadsappliedonpillarsinAMZinthispanel.Pillarwidth,basedonthismethod,isalsoobtained11.6m.Keywords:Pillardesign;Roomandpillar;Retreatmining;Activeminingzone;AbutmentloadsIntroductionInundergroundcoalmining,roomandpillaristhemethodofworkingpreferableforflat,tabulardepositsinthinseams,whereroomsofentriesaredriveninthesolidcoaltoformpillarsinthedevelopmentpanels(Hustrulid,1982;Hartman,1978).Pillarsofcoalareleftbehindtosupporttheroofandpreventitscollapse,therebyallowingminerstoextractcoalbetweenthemandtotravelsafely.Insomecases,thepillarsareremovedpartlyorfullyinalateroperation,knownasretreatmining(alsoknownassecondaryminingorpillarrecoveryoperation).Coalminepillardesignhasbeenthesubjectofsustainedandintensiveresearchinthemajorcoalproducingcountriesintheword.Pillardesignandstabilityaretwoofthemostcomplicatedandextensiveproblemsinminingrelatedtorockmechanicsandgroundcontrolsubjects.Althoughtheseproblemshavebeeninvestigatedforalongtime,todateonlyalimitedunderstandingofthesubjecthasbeengained.ThesubjectofpillardesignintheUSgoesbacknearlyacentry.Priortothisthedimensionsofpillarwerelargelydeterminedrulesofthumbsuchresearchastherewastendedtobeisolatedandsporadic.Butnowadays,variouspillardesignformulasaredeveloped,baseduponlaboratorytesting,full-scalepillartesting,andback-analysisoffailedandsuccessfulcasehistories.In1980,fieldstudiesconductedbytheUSBureauofMineshasdevelopedtheclassicpillardesignmethodology.Itconsistedofthreesteps(Mark,2006):1.Estimatingthepillarload;2.Estimatingthepillarstrength,and3.Calculatingthepillarsafetyfactor.Thaveragepillar,inregularlayoutsofpillarscanbeestimatedbytributary-areatheory,eachindividualpillarisassumedtocarrytheweightoftheoverburdenimmediatelyaboveit.Intheotherwords,apillaruniformlysupportstheweightofrockoverlyingthepillarandone-halfthewidthofroomsandentriesoneachsideofthepillar(Peng,1978).Pillarstrengthcanbedefinedasthemaximumresistanceofapillartoaxialcompression(BradyandBrown,1993).Empiricalevidencesuggeststhatpillarstrengthisrelatedtobothitsvolumeanditsshape(SalamonandMunro,1967;BradyandBrown,1993).Numerousformulashavebeendevelopedthatcanbeusedtoestimatethestrengthofpillarsincoalmines,whichTable1showsthemostapplicableofthem.Eachoftheseformulasestimatesthetopillarstrengthintermsoftwovarious;widthtoheightrationandinsitucoalstrength.Bieniawski(1981)representedverygoodclassicapproachtopillardesign.Heatfistdescribedtheissuesinvolvedinpillardesign,andadvantagesandshortcomingsoftheavailablemethodsandthenrepresentedalogical,step-by-stepapproachtodeterminethecoalpillarsdimensionsinroomandpillarmines.Table1 Mostapplicableofempiricalstrengthformulaforcoalpillars.Pillarstrengthformulas(MPa)ReferencePillarcross-sectionRemarksSalamonandMunro(1967)SquareBieniawski(1968)Square—Madden(1991)SquareMarkandChase(1997)Square—Nowadaysinmostoftheroomandpillarminesinordertoincreaserecoveryandproductivity,remanentpillarsinpanelsarerecoveredbyretreatmining.Since,theabovementionedmethodsarenotappropriateforpillardesignbecausethesemethodsneglecttheabutmentloadsduetoretreatminingandcreationofaminedoutgob.Abutmentloadsaffectonthepillarintheadjacentofpillarlineandaloadmorethantheoneestimatedbutributaryareatheoryappliedonpillar(MarkandChase,1997;Peng,1978).StudiesconductedbyvanderMerwe(19990)confirmtheincreaseofloadonthepillarsintheadjacentofthepillarline.Hecalculatedtheactualloadappliedonthepillarduringpillarrecoveryusingatwodimensionalboundaryelementmodelandestimatedthepillarsafetyfactorforthiscondition.Pillardesignwithouttheabutmentloadstofailureofpillarduringretreatmining.Pillarfailurescontinuetobeonethegreatestsinglehazardsfacedbyundergroundcoalminer,Pillarfailureresponsibleforunsatisfactoryconditionsincludes(Marketal.,2003):1.Pillarsqueeze,2.Massivepillarcollapse,and3.Coalpillarbumps.Theoccurrenceofpillarfailureinundergroundminesentailsdetrimentaleffectsonminersintheformofinjury,disabilityorfatalityaswellasminingcompanyduetodowntimes,interruptionsintheminingoperations,equipmentbreakdowns,etc.Forexamplein1992,airblastsduetopillarfailureatasouthernWestVirginiamineledtodestroyingof103ventilationstopping(Marketal.,1997).OnAugust6th,2007,violentcoalbumpoccurredinCrandallCanyonMineinUtah,andcausedtheentrappingofsixothers(Heasley,2009a).So,properpillardesignisthekeytopreventofpillarfailureandtheAnalysisofRetreatMiningPillarStability(ARMPS)programsareusedsuccessfullyfordesigningsaferetreatmining(Tuluetal.,2010).LaModelisaPC-basedprogramforcalculatingthestressesanddisplacementincoalminesorotherthinseamorveintypedeposits(HeasleyandBarton,1999;Heasley,2009b).Itisprimarilydesignedtobeutilizedbyminingengineersforinvestigatingandoptimizingpillardimensionsandlayoutsinrelationtooverburden,abutmentandmultipleseamstresses.Theprogramwasdevelopedbasedondisplacement-discontinuityvariationoftheboundaryelementmethod.MarkandChase(1997)developedtheARMPSprogrambasedonempiricalequations.ARMPSconsideringtheactiveminingzone(AMZ)calculatesstabilityfactor(ARMPSSF)basedonestimatesoftheloadsappliedto,andtheload-bearingcapacitiesof,pillarsduringretreatmining.Morethan150casesofretreatminingwerecollectedinUStoverifytheprogram(ARMPShelp,2008).Analysesofallthesecasesshowthatpillarsqueezeisthemostfrequenttypeoffailureandoccursinabouttwothirdsofcases.14casesofpillarsuddencollapseswereobserved,whichineverycaseoccurredwhentheARMPSSFwaslessthan1.5andwherethepillarwidthtoheightrationislessthan3.Allbut3ofthe17bumpsoccurredwhenthedepthofcoverexceeded400m.MarkandChase(1997)understoodthatalmostnoconsiderablemassivepillarcollapsesoccurswhenthepillarwidthtoheightrationmorethan4isselected.Theyalsoobservedwhenthedepthofcoverislessthan200m;theminimumrequiredstabilityfactortopreventmassivepillarcollapsesis1.5.Oneofthekeystominerssaftyandefficientrecoveryofthereservesistodesignsufficientlysizedpillarsthatwillpreventpillarsqueezes,excessivepillarspallingseverefloorheave,rooffalls,andpillarbumps.Regardingtheabovementionedcomments,anewmethodtodesigncoalpillarswithsquareshapeinroomandpillarminesispresentedinthefollowingsections.Theproposedmethodissuitableindeterminingoptimumpillardimensionsinroomandpillarmineswhereremanent,pillarsaresupposedtobeextractedafterpreliminaryminingcompletion.Thismethod,inadditiontoconsideringabutmentloads,lowerspillarfailurerisk.Thegoalofthismethodistohelpensurethatthepillarsdevelopedforfutureextractionareofadequatesizeforallanticipatedloadingconditions.MethodologySimilartotheARMPSprogram,theproposedmethodinthispaperconsidersthepillarsintheactiveminingzone(AMZ)becausethesepillarsareexposedtomaximumloadthroughoutminingprocessthereforethepillardimensionsobtainedbythismethodismoresatisfactory.Beforedescribingthedesignmethod,adescribingontheAMZisnecessary.AsshowninFig.1,AMZincludesallofthepillarsontheextractionfront(orpillarline),andextendsoutbythepillarlineadistanceof5timesthesquarerootofthedepthofcover.ThiswidthofAMZwasselectedbecausemeasurementsofabutmentloadfallswithinitsboundaries(MarkandChase,1997).Theproposedmethodisbasedinfiveprinciples(Ghasemietal.,2010a):CalculatingthemaximumloadappliedonthepillarsinAMZ(includingdevelopmentload,abutmentloads),Calculatingtheoverallload-bearingcapacityofpillarsinAMZ,Selectinganappropriatesafetyfactor,Calculatingthepillarwidth,andCorrectingthepillarwidthtofindtheoptimumpillarwidth.Themethodismadeupoftwelvestepswhicharedescribedbelow.Fig,2alsoillustratesdifferentstepsofthismethodinaflow-chartplot.ThesymbolsusedhereareprovidedinTable2.2.1.Step1:GatheringessentialdataEssentialdatatodeterminetheoptimumpillardimensionsinthismethodareasfollowing:Fig.1.SchematicshowoftheAMZ(MarkandChase,1997)Depthofcover:averageoverburdenthicknessoverthepillarsystem.Pillarheight(Miningheight):notethatthevalueofpillarheightisnotnecessarilyequaltotheseamthickness.Entrywidth:entrywidthisusuallydeterminedbaseonroofrockquality,productionrateandoperationalwidthofequipments.Inthismethod,crosscutsareassumedtohavethesamewidthastheentries.Insitucoalstrength.Meanunitweightoftheoverburden.Abutmentangle:theabutmentangledetermineshowmuchloadiscarriedbygob.Measurementoflongwallabutmentloadsindicatedthatanabutmentangle21°isappropriatefornormalcavingconditions.Forexample,ifnocavinghasoccurredabutmentangleis90°namelyzeroloadtransfertothegob(MarkandChase,1997).Panelwidth:panelwidthisusuallydeterminedbaseongeotechnicalconditions,stressstateintheregion,economiccriteria,andenvironmentalconditions.Panelwidthaffectsonstressdistributionloadingconditionsandcavingmechanism.Anincreaseinpanelwidthresultsinanincreaseoftheabutmentloadsappliedonthepillarsadjacenttothegobarea.Thetensionzoneheightdevelopedintheroofofthegobareaalsoincreaseasthepanelwidthincreaseandmayleadtoalargefailureinoverburden(Bieniawski,1987).Basedonwidthtodepthration(P/H),panelaredividedintocategories:·Sub-criticalpanels(P/H<2tanβ)，and·Super-criticalpanels(P/H≥2tanβ).CoalMineRoofRating(CMRR):thisindexisusedtoevaluateroofrockquality.In1994theCMRRwasdevelopedtofillthegapbetweengeologiccharacterizationandengineeringdesign(MarkandMolinda,2005).Thisclassificationsystemconsidersgeotechnicalfactorssuchasroofrockstrength,beddingandotherdiscontinuities,moisturesensitivityoftheroofrock,groundwater,etc.CMRRvariesbetweenzeroand100.Basedonthisindex,roofrocksincoalminesareputinthreecategories(Chaseetal.,2002):·Weak(CMRR<45),·Intermediate(45<CMRR<65),and·Strong(CMRR>65).2.2.Step2:CalculatingAMZdimensionsAMZlengthandwidtharedeterminedfromEqs.(1)and(2)respectively: (1) (2)2.3.Step3:CalculatingdevelopmentloadDevelopmentloadareresultedfromtheoverburdenweightoveractiveminingzone.Basedontributaryareatheory,developmentloadsareobtainedfromthefollowingequation: (3)2.4.Step4:CalculatingthemaximumfrontabutmentloadRetreatminingstartswiththeextractionofthepanelpillars.Whenenoughofpillarshavebeenextracted,theoverburdenstrataabovetheextractedpillarsstarttocave.Asaresultofthisroofcaving,theactivegobiscarriedbythegob,butaconsiderableamountoftheoriginaloverburdenloadoverthegobistransferredtothepillarsinAMZandbarrierpillarsasafrontabutmentload(seeFig.1).Frontabutmentloadiscalculatedbasedonabutmentangleconcept(Mark,1992;Tuluetal.,2010)anditsdistributionisdifferentinsub-criticalandsuper-criticalpanels(seeFig.3).Dependingonwhetherthepanelissub-criticalorsuper-critical,themaximumfrontabutmentloadisgivenbuEqs.(4)and(5)respectively(Ghasemietal.,2010a): (4) (5)2.5.Step5:CalculatingsideabutmentloadThegobareabesidetheminingpanelisthesourceofsideabutmentload.Twogobareasmayexistbesideeachminingpanel.ThesideabutmentloadissharedbetweenthebarrierpillarandtheAMZ.Thisloadthesameasfrontabutmentiscalculatedbyabutmentangleconcept.GobareawidthandbarrierwidtharerequiredtocalculatesideabutmentloadappliedonAMZ.DependingloadisgivenbyEqs.(6)and(7)respectively(ARMPShelp,2008): (6) (7)Inbothofthem,regarding Eqs.(8),Ris: (8)FactorRistransferratethatshowsthepercentageoftotalsideabutmentloadthatisappliedtoAMZ.2.6.Step6:CalculatingthemaximumloadonAMZThemaximumloadappliedonthepillarsinAMZiscalculatedbysummationofdevelopmentload,maximumfrontabutmentload,andsideabutmentloadaccordingtothefollowingequation: (9)Fig.2.Flowchartforproposedcoalpillarsdesignmethod2.7.Step7:DeterminingnumberofentriesThenumberofexistingentriesisusuallydeterminedbasedonpanelwidth,rockmechanics,operationequipments,andproductionrate.Atleastfourentriesareneeded;oneforaccommodatingtheconveyor,oneforfreshair,andwoothersintwosidesofpaneltotaketheaieout(Stefanko,1983).Economicallyandoperationally,thisnumberofentriesisnotadequateincontinuous(mechanics)miningmethodandatleastfiveentriesshouldbeplannedwhichthisnumberincreasesuptosevenentriesinmineswithhighproductionrate(Hartman,1987).2.8.Step8：Calculatingtheload-bearingcapacityofAMZTheload-bearingcapacityofthepillarsinAMZiscalculatedbysummingtheload-bearingcapacitiesofallofthepillarswithinitsboundaries.Theload-bearingcapacityofeachpillarisdeterminedbumultiplyingtheirstrengthbytheirload-bearingarea(MarkandChase,1997).Inthismethod,pillarstrengthisestimatedusingtheBieniawski'sstrengthformula.ThenumberofexistingpillarsinAMZiscalculatedaccordingtothefollowingequation: (10)Hence,theoverallload-bearingcapacityofpillarsinAMZisgivenbythefollowingequation: (11)2.9.Step9:SelectinganappropriatesafetyfactorTheselectionofanappropriatesafetyfactorcanbebasedonasubjectiveassessmentofpillarperformanceorstatistcalanalysisoffailedandstablecases(SalamonandMunro,1967;Mark,1992).AccordingtothestudiesbyChaseetal.(2002),Table3providessuggestedsafetyfactorsforstabilityofthepillarsinAMZ.Thesevaluesareobtainedfrom250analysesofpaneldesigninUSandasitisseenfromtable,safetyfactordependsonCoalMineRoofRating(CMRR)aswellasdepth.2.10.Step10:CalculatingpillarwidthInthisstep,puttingthesafetyfactorinEqs.(12)andsolvingit,pillarwidthisobtained: (12)2.11.Step11:CorrectingpillarwidthtodecreasethepillarfailureriskAsitispointedoutbefore,oneifthewaystodecreasepillarfailurerisk,especiallylargepillarcollapse,istochooseapillarwidthtoheightrationlargethan4.Inthisstep,iftherationoftheobtainedwidthfromtheprevioussteptopillarheightissmallerthan4,pillarwidthisincreasedsoapillarwidthtoheightrationlargerthan4isreached.Ofcourse,inordertocontrolandavoidexcessiveincreaseofpillarwidth,therecoveryrateistakenintoconsider.Accordingtoexperimentsandconsideringeconomicpurposesinpreliminaryminingstage,themostsuitablerecoveryratevariesfrom40%to60%.Itshouldbenotice0.5misaddedtothepillarwidtheachtimeinthisstep.Table2 UsedsymbolinproposedcoalpillarsdesignmethodSymbolDescription(unit)AMZActiveminingzoneHDepthofcover(m)Renewaltable2pPanelwidth(m)hPillarheight(m)BEntrywidth(m)Meanunitweightoftheoverburden(KN/m3)Abutmentangle(°)AMZlength(m)AMZwidth(m)Developmentload(KN)Maximumfrontabutmentload(KN)Sideabutmentload（KN）Sidegobwidth(m)Barrierpillarwidth(m)Transferrate(%)MaximumloadappliedonAMZ(KN)Pillarstrength(MPa)NumberofentriesNumberofpillarsinAMZOverallload-bearingcapacityofAMZ(KN)SafetyfactorPillarwidth(m)WidthdifferenceOptimumpillarwidth(m)Fig.3.Abutmentangleconceptinsub-criticalandsuper-criticalpanels(Mark,1992)Table3 SuggestedsafetyfactorforstabilityofthepillarsinAMZDepthofcover(m)Weakandintermediateroof()Strongroof()2.12.Step12:DeterminingtheoptimumpillarwidthInthisstep,thewidthobtainedfrompreviousstepiscorrectedsothattheoptimumpillarwidthisdeterminedbasedonthenumberodpillarsineachrowandthepanelwidth.Inordertoatfirst△shouldbecalculatedusingEqs.(13).If△islessthanorequaltothesumofpillarwidthandentrywidth,theoptimumpillarwidthisobtainedfromEqs.(14).Otherwise,thenumberofentriesisaddeddependingon△valueandcalculatingarerepeatedfromstep8: (13) (14)InthefollowingsectionoptimumpillardimensionsinthemainpaneloftheTabasCentralCoalMine,locatedinmid-easternpartofIran,isdeterminedinordertovalidatetheproposedmethodandresultsareinterpreted.ThismineisthefirstmechanizedoneinIrandesignedasaroomandpillarmine.Thepillarsareleftbehindinthisminearesupposedtobeextractedasretreatmininginfutureafterthepreliminaryminingfinishes.Thereforeaproperpillardesigncanhasaremarkableinfluenceonhighersafetyandefficiencyofthereserverecoveryinthismine.TabasCentralCoalMineTabasCentralCoalMine(TCM)isthecasestudieshere,locatedinTabascoalregionapproximately85kmsouthofTabastowninYazdprovinceinmid-easternpartofIran(Fig.4).ThemineisworkingseamC1byroomandpillarmethodusingcontinuousminerandLHD.TheC1seamgradientis1in5(11°)andseamthicknessisabout2m.Theimmediateroofabovetheseamtypicallyisweak(CMRR=37)andconsistof0.1~0.2mthickmudstone,siltstone/sandstoneinterfacesandsandstonechannelsinsomeareaswithin3mwhichhavepotentialtobewater-bearing.Theimmediatefloorisabout1~1.3mofweakseatearth/mudstoneunderlinebystrongermudstones,siltstones/sandstones.Theminablereserveaccountsfor6milliontonesofcokingcoal(CentralMineDesignReport,2005).Theinsitustrengthofcoal,basedonresultsfromuniaxialcompressivetestsandGsddyequations(Bieniawski,1987),is6MPa.AscanbeseeninFig.4thesuggestedlayoutforthismineincludestwoaccessdrifts,amainpanel,andeasternandwesternpanelsinbothsidesonthemainpanel.Themainpanelisinitiallydevelopedin2004withfiveentriesandpillarswith20×20mdistancebetweencenters.Thispanelisdevelopedwithacontinuoushaulagesystemwith4.5mwideentriesandcrosscuts.So,pillarsleftbehindthispanelaresquareshapedandwidthis15.5m.Becauseofweakfloor,thepillarheightisnotequaltotheseamthicknessandis2.6m.Thecurrentrecoveryrateis40%.AccordingtonegotiationswiththetechnicalofficeandthecavingbehaviorobservedinthemineNo.1(neartheTCM),abutmentangleinTCMis25°,sothemainpanelissuper-critical(Ghasemietal.,2010b).Becauseofextractingthepillarsleftbehindintheeasternandwesternpanelspriortobeginningretreatmininginthemainpanel,gobiscreatedinbothsidesofthispanel.ThereforesideabutmentloadshouldbeconsideredincalculationofthemaximumloadappliedonpillarsinAMZ.Thegobareasaresuper-criticalandthebarrierpillarwidthinbothsidesis30m.Accordingtothedescriptionsgiveninthissection,theparametersrequiredinpillardesigninthemainpaneloftheTCMaresummarizedinTable4.Fig.4.LocationandsuggestedlayoutoftheTCMResultsTheresultsofproposedmethodformainpanelofTCMaresummarizedinTable5.BasedonTCMconditions(i.e.,depthofcover=85mandCRMM=37)theminimumsuitablesafetyfactorforpillarsstabilityis1.5(seeTable3).AscanbeseeninTable5thenumberofentriesequaltosixandoptimumpillarwidthequalto11.6mwereobtained.Incomparisonwithoriginalminelayout,oneunitwasaddedtoentrieswhichcanincreasetheproductionrateifefficientmanagementisapplied.Furthermorepillarwidthwasdecreasedremarkably(about4m)whichcauses8%increaseinrecoveryratethatshowstheproposedlayoutissmoreeconomic.Also,itcanbeseenthatthedevelopmentload,frontabutmentloadandsideabutmentloadconstitutes73%,19%and8%ofthetotalloadappliedonpillarsinAMZrespectively.ThenegligiblesideabutmentloadcanbeattributedtothegreatwidthofbarrierandpillarsinAMZsoasthebarrierpillarswidthincrease,themoreloadwillappliedtothem.Toconfirmtheresultsofproposedmethod,optimumpillarandotherrelatedparametersoftheTCMwereenteredasinputdatatoARMPSprogramandacceptablestabilityfactorswereobtained,whichindicatestheminingoperation,inboththepreliminaryandsecondaryminingstage,issafe.Table4 EssentialdataforpillardesignintheTCMParameterValueParameterValueH85m25KN/m3h2.6mβ25oB4.5mP85mS16MPaCMRR37Table5 SummaryforresultsforTCMParameterValueParameterValueLAMZ80.5mML10.87×106KNWAMZ46.1mNE6DL7.89×106KNwp11.6FL2.05×106KNRr248%SL0.93×106KN5.DiscussionandconclusionsPillardesign,especiallyinroomandpillarmines,isoneofthemostimportanttopicsinthefieldofcoalminegroundcontrol.VariousmethodshavebeensuggestedinrecentyearsmostofwhichlikeclassicmethodandBieniawskimethodneglectabutmentloads