煤矿软岩巷道支护强度优化外文文献翻译中英文翻译Word格式.docx

煤矿软岩巷道支护强度优化外文文献翻译中英文翻译Word格式.docx

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Whenanundergroundroadwayislocatedinsoftrockswhicharetoosofttobereinforcedbyboltingand/orunsuitableforrockinjectionbecauseofrestraintsimposedbyeithertherockmassimpermeabilityorrockmassdeteriorationwhenwaterisencountered,externalrocksupport,suchassteelsets,thereforebecomestheonlyoptionforthestabilitycontroloftheroadway.Underthiscircumstance,thesupportintensitymeansasupportforceactingperunitsurfaceareaofthesurroundingrocksoftheroadway.Insoftrockengineeringpractice,thedesignofasupportpatternforaroadwayinundergroundcoalminingisnormallybasedonrulesofthumb.Inmostcases,heavysupportmeasuresareadoptedtosecureasuccessfulroadway.

Fig.1（a）demonstratestheexcellentconditionofasub-levelroadwaywithinsoftrocksatanundergroundcoalmineinnorthChina,whereanexcessivecapitalcostwasappliedfortheachievementofroadwaystability.Insomecases,suchasaserviceroadwaydriveninsoftrocksatthesamemine（Fig.1（b））,insufficientsupportintensitywasspecifiedasaresultofalackofrelevantexperienceanddesigncodes.Consequently,failureoftheroadwaystabilitywasinevitableandanextracostwasincurredwhenthesubsequentroadwayrepairorrehabilitationwasundertaken.

Thecriticalissueinbothcasesliesinthedeterminationofanoptimalsupportintensitywhichisthefunctionofthegeometryanddimensionofaroadwayanditsgeotechnicalconditionsincludingrockmassproperties,stressconditionsandhydrologicalstatus.

Physicalmodellingusingsimulatedmaterialsbasedonthetheoryofsimilarityprovidesadirectperceptionalmethodologyformininggeomechanicsstudy[1-6].Usingsimulatedmaterialsofthesamecompositiontoconstructaroadwayanditssoftsurroundingrocks,applyingacertainmagnitudeofsimulatedsupportintensitytothesurfaceofaroadwayundersimulatedstressconditions,thethree-dimensionalphysicalmodellingmethoddepictedinthisNoteemonstratesaquantitativesolutionforstrategicdesignofroadwaysupportconcernedwithsoftrocks.Arelationbetweenthesupportintensityanddeformationofthesurroundingrocksofaroadwayhasbeenestablishedafteraseriesofsimulationtestshadbeenconducted.Adiscussionontheoptimalsupportintensityforaroadwayinsoftrocksisalsogiven.

Fig.1.Examplesofsuccessfulandunsuccessfulsupportofundergroundroadwayswithinsoftrocks:

（a）Goodconditionofasublevelroadway,（b）Unsuccessfulsupportofaserviceroadway.

2.Featuresofthethree-dimensionalphysicalmodelling

Aphysicalmodellingstudyoftheinteractionbetweensupportintensityandroadwaydeformationwascarriedoutusingthethreedimensionphysicalmodellingsystem（seeFig.2）attheCentralLaboratoryofRockMechanicsandGroundControl,ChinaUniversityofMiningandTechnology.Featuresofthissystemaredescribedinthefollowingsub-sections.

Fig.2.Three-dimensionalloadedphysicalmodellingsystemattheCentralLaboratoryofRockMechanicsandGroundControl,ChinaUniversityofMiningandTechnology.

2.1.Sizeofthephysicalmodel

Theeffectivesizeofaphysicalmodelis1000mmwide,1000mmhighand200mmthick.

2.2.Threedimensionalactiveloadingcapability

Sixflatjacksareusedtoapplyloadstothesixsidesofthephysicalmodelintheformofarectangularprism.Eachflatjackwasdesignedtocoverthefullareaofoneofthesixsidesandbecapableofapplyingapressureofupto10MPaontothesurfaceofthesimulatedrockmass.Thismeansthattheflatjacksarecapableofapplyinganactiveloadofupto1000tonnesand200tonnessimultaneouslyonthefrontandbackfacets,thetopandbottom,andthetwosidefacetsofamodel,respectively.

2.3.Long-termcontinuousloadingcapability

Ahigh-pressure,nitrogen-operated,hydraulicpressurestabilisingunitwasemployedtomaintainaconsistentmagnitudeofloadappliedtothemodelsothatthephysicalmodellingtestisabletolastcontinuouslyforweeks,monthsorevenyearswithoutinterruption.Thisfeatureensuresthatthestudyofthelong-termrheologicalbehaviourofsoftrockscanbecarriedout.

3.Physicalmodellingtests

Physicalmodellingofanundergroundroadway/tunnelwithinsoftrockswithahydrostaticstressconditionwascarriedout.Thesamesimulatedmaterialswererepeatedlyusedsixtimestoconstructsixphysicalmodels.Eachroadwaymodelwasprovidedwithadifferentmagnitudeofsupportintensity.

3.1.Geotechnicalconditionsfortheprototypeandthemodellingscale

Aspecifiedundergroundroadwaywithinsoftrockswasassumedtobetheprototypeforthemodellingstudy.Detailedgeotechnicalconditionsoftheroadwayanditssurroundingrocksare:

circularroadwaywithadiameter（D）of4.5mandcross-sectionalareaof16m2;

UCS（Rc）ofthesurroundingrockwas20MPa;

bulkdensityofthesurroundingrockwas2500kg/m3;

depthoftheroadwaylocationwas500mbelowsurface;

rockmassstress（s0）was12.5MPainalldirections;

supportintensity（pa）tobeappliedtotheroadwaywas0.1,0.2,0.3,0.4,0.5and0.6MPa,respectively.

Thegeotechnicalmodellingscale（Cl）determinedwas1:

25.Thebulkdensity（gm）ofthesimulatedrockmassmaterialswas1600kg/m3.Therefore,alltherelatedsimulationconstantsare:

similarityconstantforbulkdensity:

Cg¼

1600/2500=0.64;

similarityconstantforstrength:

Cs¼

ClCg¼

0:

256;

similarityconstantforload:

CF¼

CgC1¼

4:

09610ÿ

5;

similarityconstantfortime:

Ct¼

Cl:

5¼

2:

Geotechnicalconditionsofthesimulatedrockmass

androadwaywerederivedfromthoseoftheprototyperockmassaspresentedbelow:

strengthofthesimulatedrockmass:

Rm=RcCs=0.512;

diameterofthesimulatedroadway:

Dm=DCl=180mm;

loadintensityonthefacetsofthemodel:

pm=s0Cs=0.32MPa;

Simulatedsupportintensity:

pam=paCs=0.00256,0.00516,0.00768,0.01024,0.0128and0.01536MPa;

respectively.

3.2.Realizationofsupportintensityinphysicalmodelling

Duetotherestraintsofthesmalldimensionsofthemodelroadwayonthesimulationofsupportstructure,thesupportpatternandstructurewereunabletobesimulated.Instead,anequivalentsupportintensitywassimulatedandappliedtothesurfaceofthesurrounding

rockofthemodelroadway.AStaticWaterSupportandDeformationMeasurementSystem（SWSDMS）wasdesignedspecially.Fig.3illustratestheSWSDMSbeinginstalledinthemodelroadway.ThemechanismofSWSDMSistouse4separatewatercapsulestoapplyasupportintensitytothesurfaceoftheroadwayroof,twosidewallsandfloor.Fourrubbertubes,eachofwhichwaslinkedtoawatercapsuleandfilledwithwater,wereusedtogenerateawaterpressureatthecapsule/rockinterfaceandmeasureitthroughthewaterlevelreading.

Acertainconstantsimulatedsupportintensitywasachievedbyapplyingacertainheightofstaticwaterpressure.Achangetosupportintensitycouldbemadebychangingthewaterheightintherubbertube.Thevolumechangeofeachofthefourwatercapsuleswasmeasuredattheduetimebycollecting

andweighingthewateroverflow.Thevolumeofwatercomingfromeachofthefourwatercapsuleswasusedtocalculatetheradialdeformationofroadwaysurroundingrock,i.e.,roofsubsidence,wall-to-wallclosureandfloorheave.Theproposedsimulatedsupportintensities,i.e.,Pam¼

00256,0.00516,0.00768,0.01024,0.0128and0.01536MPa,wereachievedbyadjustingthestaticwaterlevelto256,516,768,1024,1280and1536mmhigh,respectively.

Fig.3.StaticWaterSupportandDeformationMeasurementSystem（SWSDMS）beingaccommodatedinaroadwaymodelinthereal3-Dloadedphysicalmodellingsystem.

3.3.Constructionofphysicalmodel

Thecompositionsandpropertiesofmaterialstobeusedfortheconstructionofphysicalmodelswerestudiedpriortothephysicalmodelconstruction.Giventhesignificantrheologicaldeformationofroadwaysexcavatedinsoftrock,sandandparaffinwaxwerechosenforthesimulatedsoftrock.Thepropertiesofaseriesofsand/paraffinwaxmixtureswerestudiedinlaboratoryandarepresentedinTable1.

Table1Compositionsandpropertiesofsand/paraffinwaxmixtures

Accordingtothegeotechnicalconditionsoftheprototyperockmassandthemodelscale,amixtureofsand/paraffinwaxof100:

3wasselectedtoconstructtherockmassmodel.Theproceduresinvolvedinthemodelconstructionincludecoldmixingofthesandandparaffinwax,ovenheatingthesand/waxmixtureandconstructingthephysicalmodelusingthehotsand/waxmixture.

3.4.Processofphysicalmodelling

Therealprocessofanundergroundroadwayexcavation,supportinstallationanddeformationofthesurroundingrockswithtimewassimulatedinthelaboratoryphysicalmodelling.Afterthemodelhadcooleddown,prestressingthemodel,excavationoftheroadwayunderpressure,installationoftheSWSDMSdeviceandmeasurementoftheroadwaydeformationwerecarriedoutstepbystep.Thewholeprocessofmodellingwass