夹河煤矿2.4Mt-a新井设计- 煤巷锚杆支护技术研究

目录一般部分1矿区概况与井田地质特征 页英文原文TheoreticalanalysisandNumericalSimulationStudyonfailuredepthofcoalseamsfloorcausedbyminingunderpressureShuanchengGuAngLiSchoolofArchitectureandCivilEngineeringXi'anUniversityofScienceandTechnologyXi'an710054,ChinaJianhuanWangSchoolofChemistryandChemicalEngineeringSoutheastUniversityNanjing210096,ChinaAbstract:Withminingdepthincreased,mostcoalminewillfacehighpressuregroundwaterthreat.BearingmininghasalreadybecameacoalminingmethoduniversallyemployedindeepmineofChina,oneofkeyproblemsincoalminingaboveconfinedaquiferishowtodeterminethedepthofdestroyedfloorduetomininginfluence,buttheconventionalmethodofminingfailuredepthfromcoalseamfloorincoalminingaboveconfinedaquiferpossesseshighcostandstudycyclelongandothershortcomings.Inthepaper,takingminingNo.5CoalSeamofCheng-HeMiningAreaasanexample,thispaperanalyzesamethodwhichcombinesthenumericalsimulationwiththeoreticalcalculationisbroughtforward,whilethetestingdataarecomparedwiththosefromtheinsitumeasurement,drawingdetailedreliableactualinformationcanensuresafetyinmining,itcanbedynamicallyreproducedthatthedevelopmentandfailureprocessofthewholefloorstrataduringminingadvance.Thenumericalsimulationresultseducesthe12~13mfailuredepthofthecoalseamfloorofminingworkingface,meanwhile,theresultsmaybeusedtoguidepracticewithsimilarwaterpreventionworkofaworkingfaceofbearingmininganddesignofthewatercontrolmethod,andalsoprovidescientificbasis.Keywords:coalseamfloor；failuredepthofcoalfloor；theoreticalanalysis；numericalsimulationI.INTRODUCTIONChina'scoalreservesareveryabundant,coalisalsoaverywiderange,butseveralhundredmilliontonsofcoalreservesofcoalminewateratthebottomoftheOrdovicianlimestoneaquiferconfinedthere,somineintheminingprocess,oftenbesubjectedtothreatbytheOrdovicianconfinedwaterinrush.Miningcoalintheminefloorandthefloorwithpressurizedwaterpressureundertheinfluenceoftheinteraction,willformaseamfromtoptobottomfloorrockformationminingwaterflowingfracturedzone,Theeffectiveimpermeablelayerprotectionzoneandconductionbandofwaterpressurerisezone.Theimpermeablelayerofseamfloorresistivitywatercapacitydependsontheeffectiveresistivitywatercapacityofimpermeableprotectivelayer,impermeablelayerofprotectionisonlyeffectiveinordertoeffectivelywardoffthethreatofconfinedwater.Coalseamfloorminingfailureisduetotheimpactofminingdisturbance,theoriginalgroundstressequilibriumisbroken,re-distributionofgroundstress.inthegroundstresstoreachanewequilibrium,theremustbethereleaseofstrainenergy,sothatminingwaterflowingfracturedrockzoneStructurechange.Therefore,theresistivitywatercapacityofminingwaterflowingfracturedrockzoneisweak,canberegardedasnon-water-blockingcapacityofrock.Confinedwaterfromtheminingpointofviewofsafety,thecorrectevaluationofminingwaterflowingfracturedzoneoftheactualthickness,thatis,thefloor-brokendepthtoaccuratelydeterminethebottomimpermeablelayerofwaterblockingtheeffectiveprotectioncapabilities.Showsthefloor-brokendepthpredictionandcontrolofwaterinrushisimportantindecision-making.Thepresentstudyminingbearingminingcoalseamfloor-brokendepth,mainlybycomprehensiveobservationsite(drillinginjectionpressurewatertestmethod,groundpenetratingradarandultrasonicdetectionmethod)[1-2],similarelasticmaterialmodelsimulationandphotoelasticexperimenttechniquesminethefloor-brokendepth.Thesemethodsareeitherthehighcostorlongcycle；eithertoosimplistictestconditions,itisdifficultinthebearingminingfloor-brokendepthapplication.Tocompensateforthisdeficiency,inthispaperCheng-HeMiningAreaNo.5seamminingfaceengineeringbackground,applicationofrockfailureprocessflow-stresscouplinganalysissystem(RFPA2D-flow)[3-6],fromtheperspectiveoffluid-solidcouplingsimulationsanalysisinhigh-confinedwaterinmining,thecoalseamfloorstratafailureprocessandfloor-brokendepth,toexplorethebasiclawofcoalseamfloor-brokendepthdevelopment.II.MININGFACEHYDROGEOLOGYCONDITIONSCheng-HeminingareaNo.5seamminingunderpressurefaceislocatednorthernfourminingareaofminefield,northandsouthsidesaresolidareas,withinNo.5seam,burieddepthof270~340m,theaverageburieddepthof300m,No.5seamaveragethicknessof4.2m.Mechanizedminingusinglong-wallminingmachine,allfallingformanagementacrosstheroof.No.5seamelevationofthefacebelowthestaticwaterlevelOrdovician+375m,theconfinedminingareas,themainfactorsforthewater-filledNo.5coalfloorthefollowingTaiyuangroupofsandstoneorK2limestonefissuresconfinedwaterandcoalbaseOrdovicianlimestone.ImpermeablelayerinthebottomminingfaceoftheOrdovicianlimestonewaterpressureis0.85~1.35MPa,inmostcasesis1.2MPa.TaiyuangroupsandstoneaquiferandthelimestoneaquiferK2forthesameaquifer,itswaterismainlyaffectedbythebottomoftheOrdovicianwatersupply,watercontentofthemedium.SecondFeng-fengcoalgroupoftheOrdovicianbasementthicklayeroflimestonekarstfissuresandcavesinpartculardevelopment,whichcontainsveryrichconfinedwater,asthehighlywateraquifers,isthesafetyofminingcoalinthisareaofthemainconfinedaquifer,water-filledchannelcomplex,heterogeneousnatureofwateristheNo.5coalseamoverlyingthemainthreatinCheng-Heminingarea.III.THEORETICALMODELAccordingtodifferenttheoreticalassumptionsandthestrengthofrockmassfailurecriteriausedforcalculatingthefloor-brokendepthofcoalseamfloorminingfacetheory,inturn,canpredictwaterinrush.Nowmorecommonlyusedcriteriaforthefourtheoreticalcalculationswere:(a)fracturemechanicsandtheMohr-Coulombfailurecriteria；(b)elasticityandMohr-Coulombfailurecriteria；(c)elasticityandtheGriffithfailurecriteria；(d)plasticitytheoryandMohr-Coulombfailurecriterion.Thespecificconditionsunder24508miningface,throughtheactualfloorrockmassstressfielddistributionlawandpropagationfeaturesoftheresearch,combinedwithMohr-Coulombfailurecriterionofrockandrockmassstrengththeoryofplasticitytocalculatetheplasticfloor-brokendepthofrockmoreinlinewiththeactualfloorfailuresitelaw,sochoosethefourth"Mohr-Coulombplasticitytheoryandfailurecriteria"asCheng-HeMiningAreadepthofbrokenfloorrockNo.5seamminingfacetheoreticalmodel.Figure1.Theschematicdiagramofthemaximumfloor-brokendepthcalculationunderthelimitstate1①-coalabutmentpressurezone；②-gobpressurezone；③-floorplasticfailurezone；2I-preharvestadvancepressurecompressionsection；II-postharvestpressurereliefexpansionsection；III-postharvestpressurecompression-stablesection；4-preharvestprimaryrockstresssectionWorkingfaceinadvancingtheprocess,thecoalseamflooralongthecoalseamstrikecanbedividedintotwostrataduetotheinfluenceofminingisdividedintothreestages:preharvestadvancepressurecompressionsection(I)；postharvestpressurereliefexpansionsection(II)；postharvestpressurecompression-stablesection(III).Thethreestagesofcoalminingstrataprocessismobileanddynamicprocess,withtheworkingfaceforwardandrepeated.Itisbecauseoftheexistenceofsuchadynamicprocessmakestherockwithinacertainrangeofthebottomedgeofthecoal,whentheeffectofabutmentpressureonitreachesorexceedsacriticalvalue,therockwillundergoplasticdeformation,theformationofplasticzone；Whentheabutmentpressurecanleadtocompletedestructionofpartofthebiggestloadofrock,theabutmentpressurebearingrocksurroundingtheplasticzonewillbeconnectedintoone,resultingingobareafloorheave,plasticdeformationthathasoccurredwillmovethegobareafloorrockmovement,andtheformationwillformacontinuousslip-linefield,andtherockthatdonotformplasticfailurewillpresentaslipsurface.Atthispoint,thedestructionoffloorrockwithintheslidinginterfacewillbethemostserious,showninFig.1.Afterthecoalmining,rockfloorwilloccurslide,theplasticzoneboundarysliplinefedinFigure1below.Damagezoneconsistsofthreeparts:activelimitarea△abfandpassivelimitarea△acd,thesliplineofthestraightlineformedbythetwogroups；squeezetransitionzoneabec,itsslip-lineofagroupformedbyalogarithmicspiral,anothergroupofradiationfrom"a"startingpoint.InFigure1,plasticzonebytheformationanddevelopmentcanbeseen,afterthecoalseamrecovery,thefloorrockduringthegobareawillproduceabutmentpressurewhentherockabutmentpressurearea(△abfinFigure1),thestressexceedstheultimatestrength,therockwilloccurplasticdeformation,Thispartoftherockmassiscompressedintheverticaldirection,inthehorizontaldirectionwillresultinexpansionofrock.Betweentheexpansiverockextrusiontransitionzonewithintherockmass(thelogarithmicspiralabecinFigure1),whilethestresstransfertothearea.Transitionregionoftherockcontinuetosqueezethepassiveregion(△acdinFigure1),becausethepassiveregionhasfreefaceinthegobarea,anditscollapseontheroleofstressthantheoriginalrockstressislower,sothetransitionzoneandpassivezoneintheactivezoneofrocktransferedtheforcewillexpandinsidethegobarea,resultingingobareafloorrockheave,whichisminedunderpressurefloorwaterinvasionpronetoreasoninthegobarea.Ananalyticalmethodforthefloorplasticzonethatbuiltonthebasisofslip-linefieldtheorylimitstate,basedonrockplasticstrengththeoryandrockMohr-Coulombfailurecriteriontodeterminethegeometryofthelimitplasticzoneinfigure1,whichreachedthemaximumfailuredepthinsidethefloorlimitplasticzoneundertheabutmentpressureofthecoaledge.In△abfIn△aegHoweverAsinTheaboveequationshowsthatthefloor-brokendepthwithdifferentanglechanges,When,wecanfindthemaximumdepthoffloor-brokenzone,isthuscalculated:Substitutionof(3)andr1of(1)shiftformula(2),wherethemaximumdepthoffloor-brokenzoneis:Where,-thewidthofthecoalseamplasticzone(m)；-floorrockweightedaverageinternalfrictionangle(°).Calculatedbytheabovefloor-brokendepthofcoalseamfloorrock,youneedtosubstitutetheplasticzonewidthofthecoaledge,throughon-siteinstallationwithintheboreholestresssensorofthecoalinternalthemeasuredvaluecanbeobtained.AccordingtoCheng-HeMiningAreaNo.5seamminingfacehascarriedonthefloorandcoalseamcorefieldsampling[7](Fig.2),andindoorrockmechanicsexperimentalresults(Fig.3),usingrockmassstrengthdiscountedmethod,calculatedthephysicsmechanicsparametersoffloorrockresultis；theplasticzonewidthofthecoaledgemeasuredbytheon-siteavailable:duringthefirstweightingtheresultis；Duringtheperiodicweightingtheresultis.Figure2.floorStratafielddrillingcorediagramFigure3.floorandcoalseamcorelaboratorytestdiagramFinally,The,andsubstitutedinto(4)drawand.Throughtheabovecalculation,wecanseeCheng-HeMiningAreaNo.5seamminingfacetofirstweightingperiodandperiodicweightingperiod,withinthefloorstratathemaximumfailuredepthcausedbytheimpactofminingisbetween11~13m.IV.NUMERICALSIMULATIONANALYSISThefailureprocessofwater-inrushfromcoalfloorandthehydraulicfracturingmechanismissame,bothareconsideredtheseestresscouplingmechanism.Withrespecttothenumericalmodelofmechanismstudyofwaterinrush,thecriticalissueisbuildingadescriptionofrockmasspermeabilityafterruptureofthemutationandtheequationofwaterhydraulictrackingtransferlaw,soastodistinguishdifferenthydraulicmechanismsofthewaterinsulationunitandwaterconductivityunit,butalsocangiveoutacorrectinterpretationofrockfracturingaboutevolutionprocesshowtoturntheimpermeablelayerintoaundergroundwatercourselayer.Thispaperappliedrockfailureprocessseestresscouplinganalysissystem(RFPA2D-flow),besides,thepaperalsosimulatedandanalysedthewholeprocessofthefloorimpermeablelayerbrokenwater-inrushfromtheseestresscouplingangle[8-10].A.NumericalModelAccordingtoCheng-HeminingareaNo.5CoalSeamgeologicalconditions,asimplifiedmathematicalmodellengthofthecouplingis260m,heightof200m,withintherangeofthecalculationmodeltheserocksofsimilarphysicalpropertieswillbesimplified,thewholenumericalcalculationmodelwillsimplify15-storystructurebodyofcoal-seriesstratatobestudied.Basedontestreportonrock-mechanicsindex,numericalmodeloftherockmaterialgroupsinaccordancewiththesequencefromuppertolower,thespecificcalculationparameterslistedinTable1.Throughexcavationbystepsthistimeexampleisusedtosimulatethefloorbytheimpactofmining,thespecificnumericalsimulationmodelshowninFigure2.Bythegeologicalmodel,thenumberofunitsis260×200,atotalof52,000units.Limitedbythecapacitymodel,thetopofthemodeladdedoverburdenlayer,itsthicknessis50m,whileoverburdenlayerbulkdensityisabout4.5timesthatofthelooseweatheredlayer,equivalenttothe225mthicknessofoverburdenlayerunderthenormalbulkdensity.Therockonlybeargravitystressandwaterpressure,thegeologicalmodeloftheexampleshowninFig.4.Figure4.MechanicsmodelofnumeralsimulationTheboundaryconditionsofgeologicalmodel:Selectedtolimitthehorizontaldisplacementonbothsidesoftheslidingbearing,whichcanmovevertically.Thebottomofthemodellimitstheverticaldisplacementoftheslidingbearing,thetwocornerpointsofbottomandsidesaretolimitthefixedsupportofhorizontalandverticaldisplacement；Setthe120mhighconstantwaterheadboundarytosimulateconfinedhydraulicforordovicianlimestonewater(Itsvalueis1.2MPa).Themodelusesstepexcavationtosimulatetheimpactofmining:includingthefirststepisdeadweightcalculationprocess,thesecondstepstartsexcavationfrom65m,eachstepis5.4m,atotalof35stepsareexcavated,accumulativeexcavationlengthis189m.TABLEI.ROCKMECHANICSPARAMETERSFORNUMERICALMODELB.AnalysisofnumericalsimulationresultsWhencoalseamdidn'tmine,thesolerockstratawaswholetobepressed,thedistributiontypeofinternalstressisuniformandgentle.Asthecoalseammined,rockstressbalanceisdamaged,theinternalstressofthefloorisredistributed,theseamfloorrockbearsabutmentpressureoftheworkingfaceroof,itmakestheflooroccurrencedisplacement-deformationofdynamicchange,resultingindestructionofpost-harvestfloor.Inthispaper,bottomoftheexcavationisastep-wise,theexcavationofthefloorofnumericalsimulationdamagebytheminingprocessisastep-wise,atotalof35timesexcavation,eachexcavationis5.4m,theexcavationofcoalaccompaniesprogressivefailureofrockstratum,thefocusofthisnumericalsimulationistoanalyzethefloorstrataprogressivefailurecharacteristicsduringtheworkingfaceadvancing,andtoanalysefloorstratafailuredepthduringtheperiodicweightingandfirstweightingoftheoverlyingstrata.Thispaperismainlyanalyzedfromthreeaspectsforthefailureoffloorstrata,includingfloorpressuredistribution,floorfailuredevelopmentprocessandthedepthofdestroyedfloor.(1)FloorpressuredistributionFromtheprevioustheoreticalanalysisshowsthatafloorofrockdeformationandfailureintheminingprocessfrominitiation-development-formationandthewholeprocessofchangereflectsthefloorrockisawholedynamicprocessofthemovingandchanges,thepaperisfromRFPA2D-flowexperimentalanalysisangleofnumericalsimulationofamorecomprehensivetostudyoncoalseamminingunderthecombinedeffectsoftheminepressureandwaterpressure.Alongthecoalseamstrikebytheinfluenceofminingcoalfloorhasthefollowingthreestages,respectivelyforpreharvestadvancepressurecompressionsection,postharvestpressurereliefexpansionsectionandpostharvestpressurecompression-stablesection,withthefaceconstantlypromotethesethreestagesrepeated.OntheBasisoftheimpactoffeatures,alongthecoalseam,accordingtothedifferentpositionsoftheimpactofminingthefloorstratawillbedividedintothreestages,namelypreharvestadvancepressurecompressionsection(I),postharvestpressurereliefexpansionsection(II)andpostharvestpressurecompression-stablesection(III).Alongtheforwarddirection,bearingpressuredistributionofthecoalseamfloorstratashowninFig.5thepressuredecreasedareainthefigureisregardedasthegobarea.Figure5.Floorstratapressuredistribution(2)FloorfailuredevelopmentprocessBythenumericalsimulationanalysisshowsthattheseamfloorstrataexperienceddevelopmentanddamageevolutioncanbedividedintotwostagesintheworkingfaceadvancing.a)Stageoffirstweighting●Withthestopefaceadvancingto10.8m(step3),inthehorizontalseamatthebottomoftheincreasedstressonthetwoareas,atthecoalseamfloorhorizontaldirectionhastwostressincreasingregion,atbothsides,thestressvalueoffacefrontageisgreaterthangoafstressbehind.Butduetothelossoftheupperrockstratasupportingrole,thegodrockfloorthatisinthemiddleofthetensilestresscancausecoalpressurereliefexpansion,whenitsweightandtensilestrengthissufficienttoresistthewaterpressure,rockmassonlyoccurelasticallydeformedandisnotdamaged,influencedepthofminingisonly2m,andalsofloorstratacankeepstable,showninFig.6-a.●Withthestopefaceadvancingto16.2m(step4),surroundingrockstressinthegodleadtostressredistribution,locatedinopen-offcutandanteriorsupportcoalwallstressconcentrationdegreefurtherincrease,bothendsoftheCoalgobscrapsfloorrockwallcompressionandshearfailureoccurredsporadically,depthofminingisonly4.8m,atthistimeelasticdeformationoffloorstratacontinuestoincrease,showninFig.6-b.●Withthestopefaceadvancingto27.0m(step6),roofbeginstoappearfractureandhasconnectedcarbonmudstoneintheroof,miningfailuredepthofcoalseamfloorhadtoquartzsandstonelayer,andinthelayertensilefailureoccurs.atthistime,inthetime-stepimmediateroofoccursfirstcollapse.Becauseofabutmentpressureeffect,failuredeepofthecoalseamfloorcontinuestodeepen,whenthefailuredepthdevelopsto9mdepth,elasticstressconcentrationareascanbepartiallyreleased,rocktemporaryreachequilibriumstate,depthoffloorfailuredoesnotcontinuedownthedevelopment,showninFig.6-c.●Whenthestopefaceadvancesto37.8m(step8),maximumcompressivestressappearsinfrontofsupportingcoalwall.Undertheeffectsofminepressure,theupperstrataofK2limestonerocksshowsupwardbendingandbulgingintensified,andalsoappearedsimultaneouslytensionfailureinthemiddleofthegoafandtensileshearfailurezoneatthetwoconstraintsendofcoalwall.ThefailurezonepassesthroughthelayerofquartzsandstoneandlinkupthroughK2limestonerocks.WhiletheroofhasbeenconductingK4rockintheupperpartofthemainroof.Whenbearingloadofthemainroofexceeditstensilestrength,themainroofoccurringfractureinevitablyleadtosharpaugmentofcoalwallpressureinthefrontofworkingcoal.atthispointthemainrooffirstweightingappears.Afterthemainrooffirstweighting,theminepressurefinallyresultinfloor-brokendepthtoreachmaximumvaluefor12.8mdepth.Aftertheminepressuredecreases,floorstratastressistobereleased.Uptonow,themaximumfailuredepthreachesupto12.8m,showninFig.6-d.b)Stageofperiodicweighting●Afterfirstweightingofthemainroof,thefaceroofrockbeamstructurechanges,roofstrataturnsintoinstabilitystatefromthesteadystate,instabilityofstratastructureinthefracturedzoneleadtooldroofperiodicweighting.Withtheperiodicbreakofthemainroof,floorstrataelasticstrainenergycanbereleased,floor-brokendepthisnolongerthedeepdevelopment.Withtheadvancingstopefaceto59.4mand75.6m(step12andstep15),themainroofhappensthefirsttimeperiodicweightingandsecondperiodicweighting,duringthetwoperiodicweighting,floor-brokendepthisabout12m.twoperiodicweightinglengtharerespectively21.6mand16.2m,showninFig.6-eandFig.6-f.（a）Seconddevelopmentalprocess(b)Thirddevelopmentalprocess(c)Fourthdevelopmentalprocess(d)Fifthdevelopmentalprocesss(e)Sixthdevelopmentalprocess(f)SeventhdevelopmentalprocessFigure6.Developmentalprocessoffloor-brokendepth●Whenthestopefaceadvancesto135m(step26),afterthefivetimesperiodicweighting,intheminedarearooffallingrockisgraduallycompacted,flooralsobeginstobecompressed.withthepassageoftime,floorstrataentersintoarecoveryprocess,depthofdestroyedfloorbasicallymaintainwithin12mrange,anddonotdeveloptothedeeper.Therefore,duringperiodicweightingofthemainroof,thedepthofdestroyedflooris12m.C)FielddemonstrationAcousticwavevelocitychangesalongwithoriginalrocklithologyandoriginalstateintherockmassforprapagationofacousticwave.becauseofmininginfluencethestressstatesofvariouspointswillchangeduringtheprocessofmining.Ifrockstratasufferfailure,acousticwavewillalsochange,compressivewavevelocityisnotablyincreased,howeverexpansivewavevelocityisdecreased,basedonthisprincipletoconstructinclinedboreholetotheseamfloorpriortopreharvest,andbeforeharvest.miningactiveprocessandpostharvestalongtheobservationboreholewererepeatedacousticwavevelocityfrombelow.Comparedwithwavevelocitychangelaw,soastoobtainpostharvestdepthofdestroyedfloor.Figure7.acoustic-waves-monitorTestingfloor-brokendepthThusatthefacewithacoustic-waves-monitorontheCheng-HeminingareaNo.5CoalSeamminingtousetheon-sitedynamicprocessofacoustictestingtechniqueformeasuringdepthofdestroyedfloorbeforeandaftermining,siteimplementationmeasuresrelationcurveofrockstratavelocityandworkingfaceindifferentdepth,fieldtestdatadrawstheconclusionthatmaximumdepthofdestroyedfloorisbetween11and13m,showninFig.7.3)Analysisoffloor-brokendepthCheng-HeMiningAreaNo.5seamminingunderpressurefaceisnumericallystudiedbyusinganewlydevelopedCouplinganalysiscode(RFPA2D-flow)ofseepageandstressesinrockfailureprocess,Theresultsshowthatthedepthofdestroyedflooris12mduringperiodicweighting,butthedepthofdestroyedflooris13mduringfirstweighting.Therefore,theimpactoffirstweightingplayedasignificantroleinfloorwaterinvasion.Somineshouldstrengthentomonitorfloorwaterinvasionduringthefirstweighting,aswellascompletesthepreventionwork.V.CONCLUSIONS1)Withthefacetofurtheradvance,miningfailureandhydraulicfailurefeaturesofseamfloorinthehorizontaldirectionshow"threesections"sub-rule,the"threesections"isalternatingappearingduringtheworkingfaceexploitationprocess,anduntilthecoalminingoperationofthecoalfacecompleted.2)Duringtheminingprocessofthecoalminingface,affectedbyminingcoalseamrangesfrom20mbeforeandaftertheworkfacewithinalongthecoalseamstrike.Byusingthenumericalsimulationanalysis,themaximumdepthofdestroyedfloorislocatedat15mbehindtheworkingface.theregionisthemosteasilydamagedpositionthatisthesmallestbearingcapacityincoalseamfloor.Therefore,mined-outareaismostpronetothethreatofwaterinrush,duringthefaceminingadvancingprocessmineshouldstrengthenthemonitoringofwaterinrush.3)Thenumericalsimulationshowsthatthefirstweightingintervalofthemainroofis34m,therangeofperiodicweightinglengthisbetween16~22m,thenumericalanalysisresultisconsistentwithactualmeasurementoutcome.Theaboveconclusionisthatthecoalseamfloorfailuredepthreachesmaximumvalueforthefirstweighting,hereisthemostpronetowaterinrushaccident；Thefloorfailuredepthforperiodicweightinghashaslittleinfluence.Therefore,mineshalltakeeffectivemeasurestopreventtheinrushofwatertothreatcoalmineproductionforthePeriodoffirstweighting.4)IntheminingprocessofNo.5CoalSeamofCheng-HeMiningArea,thedepthofdestroyedfloorisabout11~13mduringthefirstweightingandperiodicweightingofthemainroof,thisresultiscloselyconsistenttofieldtestdatawiththeacoustic-waves-monitor.中文译文矿山压力下对煤层底板破坏深度的理论分析和数值模拟研究摘要：随着矿井开采深度的加深，带压开采已经成为我国深部矿井普遍应用的一种采煤方法，这样很多矿井都将面临高压地下水的威胁。常规的承压含水层上开采的采煤方法具有成本高，研究周期长等缺点，如何评价开采引起底板破坏深度对在承压含水层上采煤具有重要意义。本文将以城郊煤矿的5号煤层为例，运用那些已经确保煤矿安全的实测数据，提出理论分析和数值模拟相结合的方法，动态的再现煤层底板破坏的整个过程。数值模拟的结果得出：在开采过程中，煤层底板的破坏深度约为12～13m。这一结果为后面相同条件下带压开采的防水工作以及防水方法的设计提供的科学依据。关键词：煤层底板，破坏深度，理论分析，数值模拟。1引言我国煤炭资源丰富且种类繁多，但是数千亿顿的煤炭资源位于奥陶系含水层下，所以在开采过程中时常受到奥陶系承压水的威胁。在煤层底板和底板承压水的相互影响下，采动煤层会形成一条从上到下贯通底板破坏带、中间完整带和原始导升带的缝隙。隔水层的阻水能力取决于隔水层的有效隔水能力，隔水层是唯一有效的保护，从而有效地抵御承压水的威胁。煤层底板采动破坏是由于开采扰动的影响，原有的应力平衡被破坏而重新分配，地应力的应力达到新的平衡，必然有应变能释放，从而使开采导水裂隙带结构发生变化。因此隔水能力较弱的岩层被视为透水层。从开采安全的角度来看，正确的评价导水裂隙带的实际厚度，即底板破坏深度，决定了隔水层的阻水能力。做好底板破坏深度的预测，对预防突水着重要作用。目前关于底板破坏的研究主要以工作面采动过程中压水试验、原位应力测试等技术手段探测矿山压力破坏深度，这些研究方法缺乏直观性且价格偏高，为了弥补这方面的不足，本文以城郊煤矿5号煤开采的工程背景，采用二维有限差分计算机软件（F-RFPA2D)，来模拟在高承压水上采煤时，煤层底板失稳破坏过程和破坏深度，旨在探讨煤层底板破坏深度的基本规律。2工作面水文地质条件城郊煤矿5号煤层开采工作面位于井田北部四开采区域内，南北两边是岩石区。5号煤层，埋深270～340m，平均埋深300m，平均厚度4.2m，采用综采式长臂工作面采煤方法，垮落法管理顶板。5号煤层上距奥陶系含水层375m，限制开采区，底板多为太原组砂岩或K2石灰岩以及矿床为奥陶系石灰岩。工作面底板隔水层中奥陶系灰岩水压力为0.85～1.35MPa，平均1.2MPa。太原组砂岩含水层和石灰岩含水层K2主要由煤层底部奥陶系供水，水源充足。峰峰组煤层是这一地区含水层中安全的可采煤层，它是奥陶系石灰岩喀斯特地貌在此区域的特殊发展，其中含有丰富的承压水，属于高含水层，充水通道复杂，异质性强，是城郊煤矿5号煤层主要危险煤层。3理论模型根据不同的理论假设和岩石破坏准则计算方法，工作面底板破坏深度能够预测突水事故。目前较常用的四个理论计算标准是：（a)断裂力学摩尔－库伦破坏准则（b)弹性摩尔－库伦破坏准则（c)弹性格里菲斯破坏准则（d)塑性摩尔－库伦破坏准则。在24508综采工作面的具体条件下，通过实际岩体应