采矿英文文献Word文档下载推荐.docx

采矿英文文献Word文档下载推荐.docx

《采矿英文文献Word文档下载推荐.docx》由会员分享，可在线阅读，更多相关《采矿英文文献Word文档下载推荐.docx（12页珍藏版）》请在冰点文库上搜索。

Beijing,PRC100083

jiangyd@yixin_zhao@

chinazhujie@

Abstract

Thenumericalapproachtotranslatorycoalbumpsanalysisisusedtoexaminetheeffectsofjointandcoalseamstiffnessontheoutburstvelocity,deformationmagnitudeoftheopeningwallandplasticzonelengthinthecoalseam.Aseriesoftestsareperformedbyvaryingthejointdipangles,spacingnormaltojointtracks,jointblocksizeandcoalseamstiffnessratiotothesurroundingrock.Resultsofjointandcoalseamstiffnesseffectsanalysisindicatethatjointdipangle,intervalspacing,blocksizeandcoalseamstiffnessratiohaveprofoundinfluencesoncoalbumps.

Theincreasingofintervalspacingandjointblocksizecangeneratelargerroadwaydeformation,lowerroadwaydeformationvelocityandlongerplasticregioninthecoalseam.Higherstiffnessratiocanalsoresultinlargerdeformation,higherdeformationvelocityofopeningwall.Coalbumpsconditionsdeteriorateasthedipanglerotatedto90degreeortheelasticzonesdisappearinthewholeactivezoneofcoalseamfordifferentspacingdistributions..

Keywords:

Coalbumps,numericalsimulation,joint,translatory

1、INTRODUCTION

Undergroundcoalbumpsisoneofthecatastrophicminefailuresresultfromsuddenreleasesofenergy.Withtheenormousamountsofreleasedenergy,coalbumpsmaycastseveraltonsofcoalmasopeningshorizontally,whichalwaysresultindestructionandcollapseofroadways,damageoffacilityevendeathandinjurytotheminers.Thephenomenonofcoalbumpscanbefoundinvariouskinroadwayshape.Coalbumpsthrowsoutlargequantityofcoalfromthewallandthentheroadwaywillbeclosedoverhundredsofmeters.

TheresearchisfinanciallysupportedbyResearchFundfortheDoctoralProgramofHigherEducationundergrantNo.20030290001.

2、MECHANISMOFCOALBUMPS

Generallyspeaking,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、NUMERICALSIMULATIONTECHNIQUE

3.1NumericalModeling

NumericalmodelingusingUDECversion3.0（ITASCA,1996）hasbeencarriedoutforTangshancoalmineinordertoinvestigatestabilityof12coalseamon14thlevel.Numericalmodelsweredevelopedforanalyzingtheeffectsofthreemainparametersofjointoncoalbumps.Thegeometryofthetwo-dimensional40m40mmodelstudiedisshowninFigure3.Accordingtotheminingdepthandoverlyingstratasituation,theoriginallithostaticstressof21Mpaisimposedonthetopboundaryofthemechanicalmodel.Moreover,thetectonicstressis25Mpaloadedontheleftandrightboundaryhorizontally.

3.2Geo-MaterialProperties

Incurrentnumericalmodeling,theMohr-Coulombmodelwasadopted.Forallcases,themechanicalpropertiesforcoalseamandboththeroofandfloorrockarelistedasthefollowing,coalseam:

elasticmodulus5.9Gpa,passionsratio0.34;

theroofandfloorrock:

elasticmodulus36Gpaandpassionsratio0.28.

4、ANALYSISOFTHERESULTS

Whenjointswithstraightjointtracesaredevelopedparalleltooneanothertheyformaset.ThesimulationfocusesonanalyzingthemultiplejointsetandcoalseamstiffnessratioK（E/E）effectsoncoalbumps.

Themodelingwasperformedintwostages.Firstly,theeffectsofjointdipangleandjointspacingdweresimulatedbyfixingthestiffnessratioK.Secondly,theeffectofKwasevaluated

4.1Jointeffectsoncoalbumps

4.1.1Jointdipangleeffects

Firstly,theeffectofjointdipangleissimulatedbychangingfrom0oto90oinincrementsof15oascounterclockwise.Itisfoundthatinallcasesthecoalbumpsconditionsdeterioratewhenthejointdipangleisrotatedtothe90degree.Thismeansthatatthesamejointspacingconditionthesteeperjointsmakethecoalseamgroweasierunstableoroutburst.Itcanbeexplainedthattheslenderlayersparalleltothewallofroadwayincoalseamwilleasilybuckleorruptureascompressedbythesurroundingrocksorinfluencedbyseismicevents.Thewalldeformationandvelocitytowardtheroadwayarerecordedbymonitoringmiddlepointofopeningwall.Withthedipangleofjointincreasing,thedeformationandtheaveragedeformationvelocityoftheopeningwallincrease.Thedistributionofsimulationresultsisalmostsymmetryto=90o.Thealterationsofspacingdistributioncouldnotchangetheeffecttendencyofjointdipangleonthedeformationanddeformationvelocityofroadway.Thejointdipangleeffectsonbothdeformationandvelocityat1.0mjointspacingareshowninFigure4（a）,Figure4（b）andFigure4（c）respectively.

4.1.2Jointspacingeffects

Thesimulationwasperformedbyadoptingjointspacingdwithvariousvaluesfrom0.25to5.0minthedipangleof45degree.Itisfoundthatlargerjointspacingcangiverisetolargerdeformationoftheroadwayandloweroutburstvelocityofthecoalseam,asshowninFigure5.Moreover,thelargerjointspacingleadstolongeractiveplasticregioninthecoalseam.

4.1.3Jointblocksizeeffects

Randomlysizedpolygonalblockswerecreatedinthecoalseamandtheaverageedgelengthofblockspecified.Thesimulationresultsindicatethatthe

sizeofjointblockscanaffectdeformationofroadwaygreatly.Biggerjointblocksleadstolargerconvergencedeformationofroadway.Thisisbecauseintactcoalseamorlargercoalblockscanstoremorestrainenergyeasily,whichwillresultindeformationofroadwayandlongerunstableprocessofroadwayafterexcavation.However,tosmallblocks,morestrainenergywasconsumedbyjointsets,whichleadstosmallerdeformationofroadfasterdeformationvelocity.

4.2Stiffnessratioeffects

Consideringtherelativestiffnessofcoalseamandsurroundingrock,thesimulationwasperformedbychangingthestiffnessratioK（E/Efrom1to15inincrementsof2.5.Moreover,thereisajointsetconsistingofmultiplejoints,whichhas=45oandd=1.0m,inthecoalseam.Itisassumedinthepresentstudythatthereduced“competence”ofthecoalseamisdirectlyassociatedwithreducedstiffnesscoal.

Thetranslatorybumpsseemtooccuronlywheretherockintheroofandfloorlayersadjacenttotheseamareabout10timesstifferandstrongerthanthecoal（Lipman,1989）.Thesimulationresultsalsoshowthatwhetherthejointspacingislargeorsmall,thedeformationoftheroadwayandtheinitialdeformationvelocityoftheroadwaywallafterexcavationincreasealongwiththeincreasingofstiffnessratio,asshowninFigure7.

5CONCLUSIONS

Resultofjointandstiffnessratioeffectsanalysisindicatethatjointdipangle,intervalspacing,joinblocksizeandstiffnessofcoalseamandsurroundingrockhaveprofoundinfluencesoncoalbumps.

Theincreasingofintervalspacingcangeneratelargerdeformation,lowerinitialoutburstvelocityoftheopeningwallandlongeractiveplasticregioninthecoalseam.Higherstiffnessratiocanalsoresultinlargerroadwaydeformation,higherinitialoutburstvelocityofcoalseam.Coalbumpsconditionsdeteriorateasthedipanglerotatedto90degreeortheelasticzonesdisappearinthewholeactivezoneofcoalseamfordifferentspacingdistributions.Thesimulationgivestheprooftothetechniquesofpreventingcoalbumps,suchasreliefblastingorreliefdrillingwhichcancausemanysmallfractures/jointsinthecoalseamadjacenttoexcavation.

Thisstudyalsoindicatesthatjointspacing,jointdipangles,jointblocksizeandthestiffnessratioplayanimportantroleoncoalbumpsorcoalseamtranslatorydeformationtotheroadway.

中文翻译

数值模拟煤层节点和刚度影响煤层突出