测绘工程外文翻译Word格式文档下载.docx

测绘工程外文翻译Word格式文档下载.docx

《测绘工程外文翻译Word格式文档下载.docx》由会员分享，可在线阅读，更多相关《测绘工程外文翻译Word格式文档下载.docx（15页珍藏版）》请在冰点文库上搜索。

thesituationwithlargeratioofdepthtothickness.Otherwise,theywouldbediscontinuousandirregular.Movementbasinanddiversedisplacementordeformationcurvesofhorizontalcoalstratashowfineregularity.Asforinclinedcoallayer（i.e.,N-Mine）,thelargestdisplacementpointwillmovetowardsthedownhillbutnotinthemiddleofmovementbasin.Subsidencecurveandhorizontalmovementareunsymmetrical.Usually,longwallminingofthestrikeworkingmethodiswidelyadopted,thegroundsubsidenceandrocklayermovementgraduallydevelopingalongthelongprofileofcoalstrata,atlastwillbekeptstable.Meanwhiletheruleofgroundmovementisobvious.Thereisnoobviousruleforthegroundmovementalongtransverseprofile,itdepends

onthegeologicalconditionofaspecificmine.Theresearchresultsbasedonthetransverseprofileofcoalstrataaredescribedinfollowingparagraphs.

3　Simulationmaterialmodelexperiment

3.1　Modelingratio

Theconstantsincludingthemodelingratioofgeometry,density,intensityandtimeneedtobedefinedformodeling.

3.1.1　Structuralsimilituderatio.

Thestratum’sthickness,miningdepthandspaceconformedtoexactproportionbetweenmodelandprototypearenecessaryformodelingexperiment.Insimulationofthesubsidence,thestructuralsimilituderatioisanessentialparameter.Usually,thelargerthestructuralsimilituderatio,themoreprecisetheresults.Thestructuralsimilituderatioshouldbetheoreticallylargeenough,butitisdifficulttooperateinfact.Itrequiresnotonlymuchexpense,butalsostrictconditions.However,theexperimentaccuracywouldnotbeaffectedbyuseofanadequatestructuralsimilituderatioandadoptionofthesuitablemeasureandmeans.ConsideringthepracticalconditionsinN-coalmineasshowninTable1,modelexperimentwouldmimictheareawith500mdeep.Ifstructuralsimilituderatiowerelittle,themodelwouldbetoobigtooperate,sothestructuralsimilituderatiochosenis1∶400（Cl）.

Table1　Rock’smechanicalparametersinN-mine

Stratum

Young’sModulus（/Mpa）

Poisson’sRatio

Cohesion（/Mpa）

Internalfrictionangle/（°

）

Uniaxialtensionstrength/Mpa

Density

/（t·

m-3）

TJ1

106495

0.3423

14.51

33.4

2.3297

-2.60

TF1

99639

0.3060

16.81

22.9

2.0685

-2.45

TF2

104693

0.3333

1.9554

-2.55

PL8

14774.5

0.2950

20.50

34.2

0.7047

-2.25

PM1

120557.5

0.2727

3.218

3.1.2　Dynamicsimilituderatio.

Dynamicsimilarityrulerequiresthatforcesconformtotheexactproportionbetweenmodelandprototype.Inexperiment,characteristicparameterreflectsforcesincludingdensity,boundarystressandintensity.Modelingmaterialcontainssand,gypsumandlime.Theadopteddensityratioisasfollows.Cr=

H/

=

=1.667,inwhich,Crisdensityratio;

r1H,No.1layer’sdensityinprototypeandr1m,No.1layer’sdensityinmodel.

3.1.3　Excavationtimeratio.

Forthelimitofexperimentcondition,thetimeproportionbetweenmodelandprototypeisadoptedbykinematicssimilarityruleundergravity,

=20.

3.2　Modelingmaterial

Presently,themodelingmaterialcommonlyusedincludesgypsummixture,limemixtureandsyntheticgummixture,etc.Mixturecontainssupportingandclottingmaterial.Normally,sand,micapowderandtalcumpowderareusedassupportingmaterialwhilegypsumandgypsum-limeusedasclottingmaterial.Consideringmaterialselecting,transporting,expenditureandavailability,sandisappliedassupportingmaterialandgypsum-limeasclottingmaterial.Furthermore,talcumpowderlayersarelaidtomimictheeffectbetweenlayers.Intensity,

/（

*

）=

/666.7;

modelframe,length×

width×

height=1.5m×

0.3m×

1.2m;

modelingrange,500mdepth（fromgroundsurfacetocoallayer）,120mwidth（alongcoallayer）,600mlength（acrosscoallayer）.Becausecoallayeristoothin,itisenlargedto5multiplethickness.Forthemeasurementofdisplacementanddeformation,14micrometersarefixedtothetopofmodel.7ofthem（No.1~No.7）aretomeasureverticaldisplacement,andothers（No.8~No.14）aretomeasurehorizontaldisplacement（Fig.1）.

Fig.1　Stratamovementaftermodelingexcavation

Fig.2　Restraintconditionandgroundmovementinnumericmodel

3.3　Excavation

Thetopofmodelisafreesurfacewhereisnoanyload.Duringexcavationmimicking,4groupsofexcavationwouldbeexecuted,and4excavationstepsareputintopracticeineachgroup.Theexcavatingstepis2centimeterslong,andtheintervalbetween2stepsis2hours.Ittakes2daysfor2groups,thusobviousdeformationcouldbemeasured.Afterfinishedexcavationofuppercoallayer,lowercoalstratumwouldbeexcavatedcontinually.SomecurvesaredrawnasindicatedinFig.3accordingtothesimulationmaterialmodel.

（a）-Inclineddeformationcurve;

（b）-Subsidencecurve;

（c）-Horizontaldeformationcurve;

（d）-Displacementcurve

Fig.3　Simulationcurvesofmaterialmodel

4　Numericanalysis

Rockhasbothelasticandplasticproperties.Therearetwokindsofforceaccordingtoelasticmechanics.Oneisplanestress,andtheotherisplanestrain.Infact,thesameresultforstresscanbeobtainedwhetherconsideringstrainornot.Thenumericanalysisinthispaperismadeforstressanalysis.Furthermore,stressanalysisisdonealongthesametransverseprofileinthesimulationmaterialmodel,thus2Dfiniteelementmethod（FEM）programissufficient.2D-σisanumericanalyzingsystemwhichsupportstherockandsoildesigning,bywhichthemechanicsstatusandcharactersofobjectscanbeilluminated.Forplottingcells,quadranglecellisusedmore

largelythantrianglecell.Cellsincoalstrataandrockstratanearcoalonearedenselyplotted.Thecellsofrockstratafarfromcoalstrataaresparse.Stratawiththinthicknessaredividedintocellsdensely.InFEMmodeling,Mohr-Coulombmechanicsmodelisestablishedtoanalyzestresssituationalongthetransverseprofile.ThedeformationsituationofproofandfloorrocklayersinthesubsidencebasinofnumericmodelisshowninFig.2.ItisseeninFig.4andFig.5thattheeffectofbeginningexcavationonsubsidenceandgroundmovementisslightly.ThedestructiondegreefigureindicatedinFig.7isdrawnwiththe2D-σprogram.Afterallexcavationstepsfinished,theeffectofshearingstrengthongroundmovementisseriousasindicatedinFig.8.Stressconcentratesonuphillanddownhillcoalwall.VariousstressesnotlistedhereforlimitedspacecanbecalculatedwithFEMprogram,suchasmaximalandminimalstress,etc.

Fig.4　X-stressafterfirstexcavationstep

Fig.5　Y-stressafterfirstexcavationstep

Fig.6　Destructiondegreeafterallexcavation

Fig.7　Shearingstrengthafterfirstexcavation

Fig.8　Destructiondegreeafterfirstexcavationstep

Fig.9　Shearingstrengthafterallexcavationstep

5　Conclusion

Theresultsofmodelingexperimentandnumericanalyzingshowthatthesubsidencecurveandhorizontalmovementcurvearenotcontinuousandsmooth,butareunsymmetricalwithsomevariationcausedbygeologicalconditions.The