外文翻译---关于二柱掩护式支架与顶板之间相互作用的研究.doc

翻译部分英文原文ASTUDYOFTHEINTERACTIONBETWEENTHE2-LEGSHIELDSUPPORTANDTHEROOFSTRATAINTRODUCTIONThe2-legshieldpoweredsupportisshowninFig.1.Itisknownthatinordertoassestheadaptabilityofapoweredsupportnormallytherearetwoprinciplestobeconsidered:Fig.12-legshieldsupportEFFECTIVENESSOFROOFCONTROLObviously,shieldsupportismucheasiertopreventthebrokenrocksfromfallingintotheworkingspace,butitismuchhardertopreventthebrokenrocksfromfallingintotheface-to-canopyarea.OnthebasisofthestatisticaldataobtainedfromtheCollieriesYang-QuanandZhai-Li,thedown-timeleadstostopproductionduetofallingroofintheface-to-canopyareaisabout40-60%ofthetotaldown-timeintheworkingface.CollapseofroofstrataalongthefacelineisshowninFig.2.Thatistosay,inafaceinstalledwith2-legshieldpoweredsupportmuchmoreattentionmustbepaidtotheproblemofimmediateroofcontrol,especiallyintheface-to-canopyarea.EFFECTONSUPPORTSTRUCTUREUNDERTHEACTIONOFROOFPRESSURERecentreportsfromsomecollieriesrevealthat2-legshieldsupporthasbeenbrokenundertheactionofroofpressure,especiallyatthejointofthecanopyandthestabilizingcylinderasshowninFig.3.Itisevidentthatthesupportingcapacityofthistypeofsupportcouldnotbeconsideredasadequatetosomesuchkindofroofconditionsandmustbeimproved.Fig.2CollapseofalongwallfaceatthefacelineFig.3DamageatthejointofthestabilizingcylinderandthecanopyANALYSISOFLOADINGCONDITIONOF2-LEGSHIELDSUPPOIRTTheforcesactingonthecanopyof2-legshieldsupportare:theroofpressure,theforcesfromthesupportlegs,ram,hingepinofthecanopyandthecavingshield,thesurfacefrictionbetweenthecanopyandtheroofstrata.Assumingthatthesurfacefrictionandtheforceactingonthecavingshieldarenottakenintoaccount,thefollowingformulacanbeobtained:2(cossin)(cossin)bhxpbZPhLbxzbggggggThemeaningsofallthesymbolsusedinthisformulaareillustratedinFig.4a.Assumingthatcos(sin)/Ahbgsin(cos)/BhLzbgthenwecanobtainthefollowingformula.()AxpZpzBxgggItcanbeseenthatWhenPisincreasedtotheyieldloadP+,theforcethusintheramwouldbedistributedasshownincurveZintheFig.4b.Infacttheramhasayieldloadinpushandpull.Forexample,fortheshieldsupportW.S.1.7,theyieldloadinpushisequalto67.7tandinpull62.4t.SothecurveoftheforcefromtheramwouldberedistributedinthefaceascurveZ+,andthecurveofforceforthesupportlegswouldberedistributedascarvePshowninFig.4b.ThenthetotalloadPsforthewholesupportcanbegivenasfollows:1(cos/sin)(sin(cos)/)/sPPhbZhLzbWbbgg,AssumingthatW=0,then:sPPAZBggThus,accordingtothepositionwheretheroofpressureactsonthecanopyandreferthesupportperformancetotheloadoftheramZisequalto+Z,(theyieldloadoftheleg)and-CDzone,onwhichtheloadoframisequaltoZ(theyieldloadoftheraminpull).Theloadbearingcharacteristicsofthesupportlegsandtheeachzoneofthecanopyareshownasfollows:Fig.4ThreeworkingzonesofsupportcanopyzoneZ=Z+.()zB