巖石破壞過程聲發(fā)射組合定位研究

巖石破壞過程聲發(fā)射組合定位研究

1u2004范圍這是一首不同于淺表的作品。這是一首描述自由地運用自然特征的作品。它是微藻、微藻、微藻、微藻和微藻。答：這是上一個非常顯著的事件，微微熙字母沒有報告，而是報告。微微熙字母沒有報告，軟信息。它是由四種方式產(chǎn)生的。更多的微芯片研究人員專注于將微芯片應(yīng)用于三維結(jié)構(gòu)。Thestudiesconcerningmicrocrackstemporalspatialevolutionprocessinsiderockdependsonthehigh-accuracyAEeventlocation,andhenceAElocationalgorithmbecomesmoreimportant.ThestudiesofAElocationbeganinthe1960s.MOGIhadcarriedoutlinelocationandplanelocationbyusinganalyticmethodbasedonthedifferenceofP-wavearrivaltimedetectedbyfoursensors.SCHOLZhadusedthedifferenceofS-wavearrivaltimeandLeastsquarealgorithmtocalculatethelocationof22largeAEevents,andpioneeredthemethodsofAElocationcalculatedbymulti-channelssignals.Todate,manyAElocationalgorithmshavebeendeveloped.Theycanbeclassifiedintotwodifferentstylesaccordingtolocationtheory,regionallocationandpointlocation.Threetypesofsensorlocationapproacheshavebeenused,suchaslinelocation,planelocationand3-Dlocationaccordingtoarrangement.CommonlyusedAElocationalgorithmsincludeLeastsquarealgorithm,simultaneousinversionalgorithm,relativelocationalgorithm,Geigerlocationalgorithm,andsimplexlocationalgorithm.BasedontheseAElocationalgorithms,manyresearchresultsoftemporal-spatialevolutionofmicrocrackswithinrockhavebeenobtained[11-16].Inmines,therearelotsofgobsthatwouldcausestressconcentrationandresultinpillarfailure.Therefore,itisverymeaningfultomonitorpillarstabilitybyusingAEtechnique.ButtheprecisionofAEeventlocationcalculatedbytheabovementionedalgorithmsisnosatisfactorywhenthefracturepointisbeyondtherangeofsensorsarray,andhenceitcannotmeettherequirementundercomplexminingconditions.Inthiswork,acombinedAElocationalgorithmbasedontheLeastsquarealgorithmandGeigerlocationalgorithmafterAEsignalarrivaltimewasdeterminedbytheAkaikeInformationCriterion(AIC)andAutoRegression(AR)modelwaspresented.Inaddition,pillarsimulationexperimentwascarriedoutandmajoreffortwasconsideredintothecurrentstudy.Inparticular,theAEconcentratedcharacteristicsandfailuremodeswereidentifiedduringloadingonpillarspecimens.2rockpromtseciens和expomentalchnips2.1關(guān)于pb1和pb2的雙軌道藥動物和ps和wrace-perfs.3.3.3srafteriecefig..3.3.3s-part3.3.4srafterfig............日起算公司通道perf.....3.3.3indexh..................................3.3.GraniteandsandstoneemployedinthepresentstudywerepreparedinaccordancewiththesuggestedmethodsbyISRM.PB1andPB2denotesandstoneandgranite,respectively.ThecubicsamplesshowninFig.1(a)wereperformedthepencilbreaktest.ThegranitesamplesPS1andPS2wereusedtocarryoutpillarsimulationexperimentshowninFig.1(b).ThesizeandwavevelocityofrockspecimensarelistedinTable1.2.2通過非織造材料wreindexediece.silixedwrega正義s制備counewrelegulageractitywrega正義s制備coune-sraftingwrelecsqued-sg.n-roincipa之間的steassg.n-roincipa保護/案例....................................................3.EightNano30sensorswithfrequencysensitivitybetween125Hzto750kHzanda40dBpre-amplification(1220A-AST)wereusedintheAEsystem.Thesesensorswerefixedonrockfacesbygumband,andvaselinewasusedforcoupling.Plasticcushionsweresandwichedbetweensteelplatenandspecimentominimizenoisegenerationduetofriction.Figure1showsthearrangementofeightAEsensors.2.3unixialmoadingu土壤生物u2004和世界.3日起事動力的現(xiàn)實基礎(chǔ)即“u.....3”...日是網(wǎng)絡(luò)實名的u...................................................Aservo-controlledhydraulictestingmachinewiththemaximumaxialloadingof3000kNwasusedinthisexperiment.Themachinehasahighsamplingspeedtorecordtheloadanddisplacement.Inthiswork,uniaxialloadingwasappliedandtheloadingratewas20kN/min.AEsignalswerereal-timeacquiredusingamulti-channelhigh-speedAEtestingandanalyzingsystem,namelyHUS(hyperionultrasonicsystem).ThetemporalandspatialdistributionofAEeventswithinthespecimenduringloadingwasvisuallydisplayedin3Dbyusingapostprocessor.Thethresholdwassetat50dBtogainahighsignal/noiseratio.Thesamplingfrequencywassetat2MHz.Figure2showsthesystemoftheexperimentalinstruments.3區(qū)域檢測技術(shù)3.1ataofmap等參數(shù)ThedeterminationofP-wavearrivaltimeisbasedonassumingthatwaveformcanbeseenasnormalstatebeforeandafterarrival,andthebestcutpointisusedasthetimeP-wavearrivaltime.Thedataofwaveformcanbeseenasatimeseries.Thetimeseriesofndataaredividedintotwoparts,onewiththenumberofkdata,andotherwithn-kdata.Foreachvalueofk,auto-regressionmodels(ARmodel)ofkandn-kdatawereestablishedandAkaikeinformationcriterion(AIC)wasadoptedtoestimatetherationalityofthemodels.Thecriterion,Cap,isexpressedasfollows:wherel1,l2,σ12andσ22arethedegreesandvariancesofARmodelofkdataandn-kdata,respectively.ThevalueofCapofeachkiscalculatedandthetimetotheminimumvalueofCapcanbeseenasP-wavearrivaltime(Fig.3).3.2相關(guān)algorithmrequetaste和algarithmatchrateTheleastsquarealgorithmcanonlyprocessoneiterationwhoselocationaccuracyismuchlower,butwithafastconvergencerate.ThelocationaccuracyofGeigeralgorithmismuchhigher,buttheselectionofinitialiterativevalueisdifferent.Therefore,acombinedAElocationalgorithmbasedontheLeastsquarealgorithmandGeigerlocationalgorithmwasdevelopedinthiswork.BeforelocatingAEevents,AEsignalswouldbefilteredtoremovenoisesignalsandgainaccuratearrivaltimeofP-wave.Then,theLeastsquaresalgorithmandGeigeralgorithmwereusedtocalculateAEeventpositionandoccurringtimeaccordingtothedifferenceofsensorcoordinateandP-wavearrivaltime.TheLeastsquaresalgorithmhasanadvantageoffastconvergenceincalculatingtheinitialiterativevalueθ(x,y,z,t).Then,amodifiedvectorΔθ(Δx,Δy,Δz,Δt)wascalculatedbytheGeigeralgorithmineachiterationandaddedontheresultsofthelastiterationtoabstainanewiterativevalue.Theiterationcontinuesuntiltomatcharequirederrorcriterion.Figure4showstheflowchartoftheAElocationprinciple.Inthiswork,locationanalysisonAEeventsattemptstominimizethearrivaltimedifferencebetweenobservedandcalculatedones.Witheachiterativecalculation,theestimatedarrivaltimeatthesensorsiteiscalculatedandcomparedwiththeobservedarrivaltimeandanestimateoftheerrorisobtained.Absolutedeviationmethodisusedtoestimatetheerrorasfollows:whereNisthenumberofobservedarrivals;toiistheobservedarrivaltimeattheithsensor;tciisthecalculatedarrivaltimeattheithsensor.4u3000服刑人員相關(guān)程序要求EightypencilbreaktestswerecarriedoutonsurfaceofPB1andPB2specimens,ofwhichthetopandsidefaceswere50and30,respectively.Figure5showsthewaveformsofpencilbreaktestontopsurfaceofPB1specimens.Itcanseethatthesignalqualityisfine.Sensors5-8areclosetothepencilbreakpositionsandthetimeofAEsignalsarrivalisearlier,whilesensors1-4arefarawayfromthepencilbreakpositionsandthetimeofAEsignalsdetectedbysensorislater.ThroughcalculatingsignalarrivaltimebyAEcombinedlocationalgorithm,78locationresultswereobtainedfromthe80pencilbreaktestsofPS1specimensFromFig.6,itcanbeseenthatthelocationresultsofpencilbreaktestsareconcentratedonthepencilbreakpositions.ForPS1specimens,thecoordinatesofpencilbreakpositionsoftopandsidefacesare(54.5,50,198)and(54.5,0,99),respectively.Table2showsthelocationerrorsofPS1specimens.Itcanbeseenthatthelocationerrorof90%eventsislessthan10mmandtheerrorof60%eventsislessthan6mm,showingthatthelocationprecisioncanmeetthedemandofmicrocracksmonitoredbyAEtechnique.ThecombinedlocationmethodwasintroducedinthisworktoensurefulluseoftheadvantageoftheLeastsquarealgorithmtoeffectivelysolvetheproblemofinitialIterativevalue.Inaddition,thislocationalgorithmcansignificantlyspeeduptheconvergenceprocessingandreduceiterationsbytheGeigermethod,whichismeaningfulforprocessingalargeamountofAEdatageneratedduringexperiment.5內(nèi)皮拉斯盜竊器5.1specityeningspecity專業(yè)squeFigure7showsthelocationresultofAEeventsofPS1specimenswithdifferentstresslevels.Attheinitialloadingstage,20%ofpeakstressisshowninFig.7(a).ThelocatedAEeventsaremuchless,buttheyhaveclusteredinthebottomleftcorner.Thisindicatesthatstressconcentrationoccurredinthisarea.Whenthestressachieves40%ofthepeakstress,asshowninFig.7(b),AEeventsconcentrateinareaAmuchobviously,andbegintoclusterinthetoprightcornerofSP1specimens.Withstressincreasing,AEeventsarehighlycentralizedinareasAandB.Whenrockfailureoccurs,afewAEeventsalsoclusterinareasCandDshowninFig.7(e).Finally,shearfailureoccursatthejunctionofpillarandroofinSP1specimen,suchasareasAandB.The3DlocationofAEeventscandirectlyreflecttheprocessofinitiation,propagationandevolutionofmicrocracksandthestressre-distributionwithinspecimen,whichisvaluableforstudyingtherockfailuremechanism.ForPS2specimensshowninFig8,locatedAEeventsaremuchlessduringthewholeloadingprocessthanPS1specimens.But,whenrockfailureoccurs,AEeventsarealsoclusteredinareasA,BandCshowninFig.8(c).ThefailuremodelofSP1specimenissimilartoSP2specimen,shearfailureatthejunctionofpillarandroof.Itindicatesthattheareabetweenpillarandroofismuchlikelyappearancestressconcentration,whichcanbeidentifiedasadangerzoneofmacroscopicfailureandcanbeusedtoguideformonitoringminegroundpressuredisaster.5.2抗混合物4.3.4年asa&兩國atslartracketerizactroshenratches,清明清,清明清,清明清,清明清,清各物Figure9showstherelationshipsbetweenstress—strainandAErateofSP1andSP2specimensatatimeintervalof10s.ItcanbeseenthatAErateismuchhigherfromtheinitialloadingphasetoelasticdeformationphase.Thisphenomenonisdifferentfromcompleterockspecimens.Thisindicatesthatduringthewholeloadingphase,alargenumberofmicrocracksgeneratedandpropagated.Itisworthnotingthatoncetherockreachesplasticdeformationstage,AEeventsdecrease.Thisstagecanbeseenasaquietperiod.AEquietperiodisrelatedwiththerockplasticdeformation.Duringthisphase,thestressincrementwilldiminishinunittimewhenthestressapproachestothepeakvaluestrengthanditwillneedmoretimeandmicrocrackswillgraduallynucleateandlinktolargescalecracks.ZENGetal,LIetalhavestudiedb-valueofAEeventsduringtherockfailureprocess.Itsuggestedthatb-valuewilldecreaseandreachitsminimumvaluebeforerockfailurethatcanreflecttheevolutionaryprocessfromsmallscalecrackstolargescalecracks.AlthoughAErateisdecreasingduringtheplasticdeformationstage,thefracturescaleandreleasedenergyareincreasi