采矿英文文献

英文原文NumericalsimulationofcoalseamjointsandstiffnesseffectsoncoalbumpsYangdongjiang,yixinzhao,jiezhuChinaUniversityofMiningandTechnology(beijing)Beijing,[e-mail][e-mail]@163.comAbstractThenumericalapproachtotranslatorycoalbumpsanalysisisusedtoexaminetheeffectsofjointandcoalseamstiffnessontheoutburstvelocity,deformationmagnitudeoftheopeningwallandplasticzonelengthinthecoalseam.Aseriesoftestsareperformedbyvaryingthejointdipangles,spacingnormaltojointtracks,jointblocksizeandcoalseamstiffnessratiotothesurroundingrock.Resultsofjointandcoalseamstiffnesseffectsanalysisindicatethatjointdipangle,intervalspacing,blocksizeandcoalseamstiffnessratiohaveprofoundinfluencesoncoalbumps.Theincreasingofintervalspacingandjointblocksizecangeneratelargerroadwaydeformation,lowerroadwaydeformationvelocityandlongerplasticregioninthecoalseam.Higherstiffnessratiocanalsoresultinlargerdeformation,higherdeformationvelocityofopeningwall.Coalbumpsconditionsdeteriorateasthedipanglerotatedto90degreeortheelasticzonesdisappearinthewholeactivezoneofcoalseamfordifferentspacingdistributions..Keywords:Coalbumps,numericalsimulation,joint,translatory1、INTRODUCTIONUndergroundcoalbumpsisoneofthecatastrophicminefailuresresultfromsuddenreleasesofenergy.Withtheenormousamountsofreleasedenergy,coalbumpsmaycastseveraltonsofcoalmasopeningshorizontally,whichalwaysresultindestructionandcollapseofroadways,damageoffacilityevendeathandinjurytotheminers.Thephenomenonofcoalbumpscanbefoundinvariouskinroadwayshape.Coalbumpsthrowsoutlargequantityofcoalfromthewallandthentheroadwaywillbeclosedoverhundredsofmeters.TheresearchisfinanciallysupportedbyResearchFundfortheDoctoralProgramofHigherEducationundergrantNo.20030290001.2、MECHANISMOFCOALBUMPSGenerallyspeaking,coalbumpscanbeclassified(Rice,1935)intotwotypes:Oneispressurebumpswhicharecausedwhenstrongandbrittlecoalpillarsorportionsofpillarsandloadedbeyondtheirload-carryingcapacityresultinginsuddenandviolentfailure.Theotherisshockbumps,whichareattributedtorupturingofstrongstrataabovethecoalseam.[3~4]Infact,mostcoalbumpsoccurredliketranslatoryrockbursts(Lippmann,1989),whichresultincoalseamprojectingdynamicallyintotheexcavationandtheexcavationcanbeclosedoverhundredsofmeters.ThequalitativedescriptionofthemechanismofcoalbumpsisshowninFigure1.Atpre-excavationstate,theprimitiveoverburdenpressureqactingonthecoalseamcanbeassumedtobeatstaticfrictionelasticstate,showninFigure2(a).However,aftertheroadwayisminedout,theprimitiveverticalpressureexertedontheseamoverthewidthoftheexcavationshouldbetransferredontotheseamadjacenttotheexcavation[5].TheverticalpressuredistributionafterexcavationisshowninFigure2(b).Perturbationsintheoriginallithostaticstressfieldcausedbytheexcavationcan,therefore,resultincoal/jointfailureontheseamhorizons.Thus,thecoalseamcanbedividedintothreedistinctzones:thepressurereliefzoneA,maximumstaticequilibriumzoneBandtheprimitiveoverburdenpressurezoneC.Themininginducedseismic,detonationsorotheractivitiesmaycausewavesandunstablecrackpropagationinthecoalseamandsurroundingrock.Thiswillcausedecreaseofnormalstressandincreaseofshearingstresstotheinterfacesbetweenthecoalseamandtheadjacentoverlyingandunderlyingrocklayers.Theeffectsmayconvertthestickingfrictionintoaslidingfriction.Moreover,attheactivezones,thecoalseamneartheexcavationwillbeanactiveplasticregion.Onlywhenthewholeactivezonesaretransferredtobeoneactiveplasticregionatsomecondition,thecoalbumpsaremorelikelytooccur.Oncethecoalbumpsoccur,coalatAzoneandportionofBzonewilltranslatoryejecttotheroadways.3、NUMERICALSIMULATIONTECHNIQUE3.1NumericalModelingNumericalmodelingusingUDECversion3.0(ITASCA,1996)hasbeencarriedoutforTangshancoalmineinordertoinvestigatestabilityof12coalseamon14thlevel.Numericalmodelsweredevelopedforanalyzingtheeffectsofthreemainparametersofjointoncoalbumps.Thegeometryofthetwo-dimensional40m40mmodelstudiedisshowninFigure3.Accordingtotheminingdepthandoverlyingstratasituation,theoriginallithostaticstressof21Mpaisimposedonthetopboundaryofthemechanicalmodel.Moreover,thetectonicstressis25Mpaloadedontheleftandrightboundaryhorizontally.3.2Geo-MaterialPropertiesIncurrentnumericalmodeling,theMohr-Coulombmodelwasadopted.Forallcases,themechanicalpropertiesforcoalseamandboththeroofandfloorrockarelistedasthefollowing,coalseam:elasticmodulus5.9Gpa,passionsratio0.34;theroofandfloorrock:elasticmodulus36Gpaandpassionsratio0.28.4、ANALYSISOFTHERESULTSWhenjointswithstraightjointtracesaredevelopedparalleltooneanothertheyformaset.ThesimulationfocusesonanalyzingthemultiplejointsetandcoalseamstiffnessratioK(E/E)effectsoncoalbumps.Themodelingwasperformedintwostages.Firstly,theeffectsofjointdipangleandjointspacingdweresimulatedbyfixingthestiffnessratioK.Secondly,theeffectofKwasevaluated4.1Jointeffectsoncoalbumps4.1.1JointdipangleeffectsFirstly,theeffectofjointdipangleissimulatedbychangingfrom0oto90oinincrementsof15oascounterclockwise.Itisfoundthatinallcasesthecoalbumpsconditionsdeterioratewhenthejointdipangleisrotatedtothe90degree.Thismea