结构力学毕业论文文献翻译关于二柱掩护式支架与顶板之间相互作用的研究文档格式.docx

结构力学毕业论文文献翻译关于二柱掩护式支架与顶板之间相互作用的研究文档格式.docx

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Fig.12-legshieldsupport

EFFECTIVENESSOFROOFCONTROL

Obviously,shieldsupportismucheasiertopreventthebrokenrocksfromfallingintotheworkingspace,butitismuchhardertopreventthebrokenrocksfromfallingintotheface-to-canopyarea.OnthebasisofthestatisticaldataobtainedfromtheCollieriesYang-QuanandZhai-Li,thedown-timeleadstostopproductionduetofallingroofintheface-to-canopyareaisabout40-60%ofthetotaldown-timeintheworkingface.CollapseofroofstrataalongthefacelineisshowninFig.2.Thatistosay,inafaceinstalledwith2-legshieldpoweredsupportmuchmoreattentionmustbepaidtotheproblemofimmediateroofcontrol,especiallyintheface-to-canopyarea.

EFFECTONSUPPORTSTRUCTUREUNDERTHEACTIONOFROOFPRESSURE

Recentreportsfromsomecollieriesrevealthat2-legshieldsupporthasbeenbrokenundertheactionofroofpressure,especiallyatthejointofthecanopyandthestabilizingcylinderasshowninFig.3.Itisevidentthatthesupportingcapacityofthistypeofsupportcouldnotbeconsideredasadequatetosomesuchkindofroofconditionsandmustbeimproved.

Fig.2Collapseofalongwallfaceatthefaceline

Fig.3Damageatthejointofthestabilizingcylinderandthecanopy

ANALYSISOFLOADINGCONDITIONOF2-LEGSHIELDSUPPOIRT

Theforcesactingonthecanopyof2-legshieldsupportare:

theroofpressure,theforcesfromthesupportlegs,ram,hingepinofthecanopyandthecavingshield,thesurfacefrictionbetweenthecanopyandtheroofstrata.

Assumingthatthesurfacefrictionandtheforceactingonthecavingshieldarenottakenintoaccount,thefollowingformulacanbeobtained:

ThemeaningsofallthesymbolsusedinthisformulaareillustratedinFig.4a.

Assumingthat

thenwecanobtainthefollowingformula.

ItcanbeseenthatWhenPisincreasedtotheyieldloadP+,theforcethusintheramwouldbedistributedasshownincurveZintheFig.4b.Infacttheramhasayieldloadinpushandpull.Forexample,fortheshieldsupportW.S.1.7,theyieldloadinpushisequalto67.7tandinpull62.4t.SothecurveoftheforcefromtheramwouldberedistributedinthefaceascurveZ+,andthecurveofforceforthesupportlegswouldberedistributedascarvePshowninFig.4b.ThenthetotalloadPsforthewholesupportcanbegivenasfollows:

AssumingthatW=0,then:

Thus,accordingtothepositionwheretheroofpressureactsonthecanopyandreferthesupportperformancetotheloadoftheramZisequalto+Z,（theyieldloadoftheleg）andⅢ-CDzone,onwhichtheloadoframisequalto–Z（theyieldloadoftheraminpull）.

Theloadbearingcharacteristicsofthesupportlegsandtheeachzoneofthecanopyareshownasfollows:

Fig.4Threeworkingzonesofsupportcanopy

ⅠzoneZ=Z+.

.

ⅡzoneP=P+

ⅢzoneZ=-Z-

Obviously,theresistancesofⅠzoneandⅢzoneonthecanopyareproducedbytheyieldloadoftheram.Forexample,ifZisequaltozero,theresistanceofthesupportitselfinzonesⅠandⅢwouldlossandtheresistancecanbeproducedonlywhenthereexistssomeadditionalforcesfromthecorrespondingzones.InzoneⅢorⅠ.Thereexistsabalanceforceproducedbytheroofstrata.Iftheyieldloadoftheramisincreased,obviously,theintervaloftheⅡzonewouldbecomemuchwider,andtheresistanceonthezonesⅠandⅢwillbeincreasedaccordingly.ThereareshowninFig.5.

Fig.5ResistanceCurveofdifferentyieldloadofram

INTERACTIONBETWEENROOFPRESSUREANDSUPPORTRESISTANCE

Itiswell-knownthattheroofpressureactingonthecanopyofthesupportcanbedividedintotwocomponents,theyare:

Q1producedbytheimmediateroofandQ2bythemainroof,asshowninFig.6.

Asageneralrule,theimmediateroofcanbeconsideredasadiscontinuousmedia（likealoosebody）andthereisafreefacealongthecavingline.LoadQ1actssteadilyonthesupports.Loaddistributiononthecanopymaybeconsideredasuniform.LoadQ2fromthemainroofmaybeconsideredasaconcentrated

loadwhichactsontheimmediateroofandthenactsonthecanopyofthesupport.Basedonthedisplacementmeasurementofroofstrataithasbeenfoundthatthemainroofoftheoverlyingstratacanbeconsideredasastructureformedbylayersofrockblocksinterlockingwithoneanother,whenthecoalfaceadvances,eachblockbecomestomoveformingaturningblock.ThedisplacementofthemainroofisshowninFig.7.

Obviously,theactingpositionoftheloadfromthemainrooffirstlydependsonthestabilityconditionoftheblocksinthemainroof.Q2canacteitherinfrontorintherearofthecanopy.Secondly,itdependsonthepositionwheretheimmediaterooffalls.Ifthefrontsectionoftheimmediateroofisfracturedandfallsintotheworkingspace,thentheforcefromthemainroofwouldactonthecanopy.Iftheconditionisoppositetothis,thentheforcewouldactonthepositioninfrontofthecanopy.

Consequently,theroofpressureQactingonthecanopycanthuscanbecombinedfromthoseofQ1andQ2.

Fig.6RoofPressureProducedbythemainroofandtheimmediateroof

Fig.7Displacementofthemainroof

WhenthepressureQactsonzoneⅠandQ>

Ps,thereliefvalveoftheramwouldfirstlyopen,thenthefrontpartofthecanopywouldturndownwardsandthebalanceforceQ3wouldbeproducedintherearpartofthecanopymustbekeptintactormustnotcaveequaltotheresistanceforce（Ps）ofthesupport.IntheoppositeconditionthebalanceforceQ3wouldbeproducedinzoneⅠ.

FromthiswecanseethattheresistanceofthistypesupportcanthusbeformedintheconditionwhenthebalanceforceQ3occursonthecanopy.Thatistosay,theimmediateroofmustnotcaveatall.

Accordingtotheanalysismentionedabove,nowconsiderthatisunderthedifferentconditions:

TheroofisunbrokenandtheresistanceofthesupportPsisequaltoP+（theyieldloadofthelegs）.Thentheresistanceofthesupportcanbeexpressedasfollows:

Q＋Q3＝Ps

AssumePs＝P+,sothat

ThentheactingpositionwheretheroofpressureQactswouldbecome

x＝P＋（1－A）·

z/B

AssumethattheactingpositionwheretheroofpressureQactsisatx1,andthebalanceforceQ3isx3（theoriginisinthehingepinpoint）,thenthefollowingformulaisobtained:

Q·

x1＋Q3·

x3＝（Q＋Q3）·

（p＋（1－A）·

z/B）

TheroofpressureQwhichthesupportcanresistisequalto:

Take

tostandfortheefficiencyofthesupport,obviously,thishasrelationwiththefollowingfactors:

thegeometricalparametersofthesupport,i.e.parametersofthebalanceforce（reaction）oftheimmediateroofx3.Itisobviousthatthenearerthevaluex1approachestozoneⅡ,thehighertheefficiencyofthesupportwouldbe.Somethingthevaluex3canberepresentedasanindextostandfortheinteractiverelationbetweenthecanopyandtheimmediateroof.WhenQactsintheposition

thebalanceforce

isequaltozero,andtheefficiencyofsupport

isequalto1.

Fig.8showsthatwhenavariableroofpressure（Q）actsinthreedifferentpositions（x1）inthezoneⅠofthecanopyandwithdifferentindexx3inzoneⅢ,inordertoresisttheroofpressure（Q）,acorrespondingbalancereactionforceQ3withdifferentvaluesmustbegiveninzoneⅢ.Forexample,whentheroofpressureisactingonthetipofthecanopyandisequalto80tifx3>

37cm.thentherewouldbenosuchbalanceforceformedintherearpartofthecanopy.

Becauserooffalloccursintheface-to-canopyareawheretheroofwouldbecomeirregular,thusthecanopywouldhavethreekindsofoperatingconditionforthecanopytoswing:

downwards（<

0○）upwards（>

10○）andatananglefrom0○to10○.AccordingtostatisticaldatacollectedfromZhai-LiColliery,thepercentageoftheoperatingoftheoperatingconditionsofthecanopyswingingcanopyin<

0○accountsfor3.5%andthatofin>

15○,for11%.

Duetothefactthattheactingpositionoftheroofpressureonthecanopyisdifferent,theanglebetweenthecanopyandthecavingshieldmaybevariable.Table1showsthevariationaccountsfor44.8%,whichmeansthatthecanopyandthecavingshieldmaybevariable.Table1showsthevariationofthisangleineachoperationcycle.

FromTable1,wecanseethatthepercentageofpositivevariationaccountsfor44.8%,whichmeansthattheroofpressure（Q）firstlyactsonzoneⅠandthanthebalanceforce（reaction）（Q3）isformedonzoneⅢ;

finally,theactingpositionofthecombinedforce（Q+Q3）wouldmovetowardszoneⅡ.InTable1thepercentageofnegativevariationaccountsfor19.4%.

SimilarresultshavealsobeenobtainedfromfieldmeasurementsinworkingfaceNo.332ofZhai-LiCollieryasshowninTable2andFig.9.

Obviously,whethertheroofpressureactsonzoneⅠorⅢofthecanopy,iftheactingpositionofthecombinedforce（Q+Q3）movestowardszoneⅡ,theoperatingconditionofthesupportwouldbenormal.ButiftheactingpositionofthecombinedforcemovesoverzoneⅡandcontinuouslymovesforwardsorbackwards,thesupportwouldthenworkinabnormalconditions.

Fig.8BalanceforceCurvesfordifferentindexX3inzoneⅢ

中文译文

关于二柱掩护式支架与顶板之间相互作用的研究

二柱掩护式支架如图1所示。

为了评定支架的适应性，通常有两个特性要考虑：

顶板控制影响

显然，掩护式支架更容易阻止冒落矸石掉在工作面上，但是它更难阻止冒落矸石掉在遮蓬区。

根据来自阳泉和翟梨的资料显示,下落时间导致停止生产，归因于下落顶板在遮蓬区大约是40％～60％的下落时间在工作区。

顶板沿着朝向倒塌。

就是说，在一个装有二柱掩护式支架的面上更多关注的是顶板及时控制问题，特别是面