高速鐵路有軌道結(jié)構(gòu)動(dòng)態(tài)響應(yīng)有限元建模與分析

高速鐵路有軌道結(jié)構(gòu)動(dòng)態(tài)響應(yīng)有限元建模與分析

根據(jù)我國新高速客運(yùn)公線h-1號(hào)線的實(shí)際情況，以軌道結(jié)構(gòu)為研究對(duì)象，進(jìn)行了軌道結(jié)構(gòu)的動(dòng)態(tài)響應(yīng)建模和軌道不均勻破壞的動(dòng)態(tài)分析，計(jì)算了不同墊層的影響值，并分析了不同表面波的性能。包括新安裝桿的振動(dòng)特性、室內(nèi)測(cè)量精度和桿的動(dòng)態(tài)特性。研究軌道結(jié)構(gòu)的動(dòng)態(tài)特性?；谲壍揽v向條帶狀分布的規(guī)則性結(jié)構(gòu),建立軌道元數(shù)值計(jì)算方法與軌道結(jié)構(gòu)空間有限元模型。軌道元作為數(shù)學(xué)模型,從形式上表現(xiàn)為0.6m長軌枕間距的一段軌道截矩,涵蓋一根軌枕及相應(yīng)鋼軌質(zhì)量、扣件、墊層、道床及路基在內(nèi)的動(dòng)力學(xué)特性;應(yīng)用列車前后適時(shí)“增加與縮減”1個(gè)或多個(gè)軌道元的方法,進(jìn)行無限長軌道結(jié)構(gòu)動(dòng)態(tài)響應(yīng)分析。理論計(jì)算與實(shí)測(cè)結(jié)果對(duì)比表明,所建有限元模型能夠反映有砟軌道結(jié)構(gòu)的振動(dòng)特性。運(yùn)用車輛—軌道耦合動(dòng)力學(xué)理論和軌道元數(shù)值計(jì)算方法,研究不同速度與不平順幅值下無縫線路焊接區(qū)迎輪錯(cuò)牙型不平順對(duì)輪軌系統(tǒng)各部分動(dòng)力性能的影響。列車高速運(yùn)行時(shí),焊縫不平、軌面剝離與擦傷等各種軌面短波不平順均將顯著增加輪軌相互作用,加速道砟破碎與道床路基不均勻沉降,惡化軌道幾何狀態(tài),所以應(yīng)及時(shí)消除該類脈沖激擾源的影響。既有線列車提速到200km·h-1時(shí),軌道不平順是引起輪軌動(dòng)作用力的主要根源。通過確定各類不平順幅值的控制范圍,為提速線路制定軌道養(yǎng)護(hù)維修和不平順管理標(biāo)準(zhǔn)提供依據(jù)。為完善軌道結(jié)構(gòu)空間有限元分析,根據(jù)能量法和Timoshenko梁理論,運(yùn)用振型疊加法建立軸向溫度力作用下無縫線路鋼軌諧響應(yīng)有限元模型,研究不同溫度力作用下與不同軌道結(jié)構(gòu)參數(shù)影響下鋼軌的振動(dòng)特性,掌握其發(fā)展規(guī)律和變化特點(diǎn)。計(jì)算表明:隨著軸向溫度力(以拉為正)的增加,鋼軌共振頻率增大,而共振幅值呈非線性遞減;在軸向受壓溫度力作用下,上述變化關(guān)系更顯著;鋼軌類型、軌枕支承間隔長度與軌下支承剛度將一定程度上影響無縫線路鋼軌的共振頻率。根據(jù)接觸—沖擊響應(yīng)的虛位移原理,將輪軌接觸邊界條件用罰函數(shù)法釋放,采用點(diǎn)面接觸單元導(dǎo)出輪軌接觸有限元控制方程,建立軌道結(jié)構(gòu)落軸沖擊動(dòng)力有限元方程,計(jì)算高速鐵路有砟軌道結(jié)構(gòu)落軸沖擊動(dòng)態(tài)響應(yīng),分析采用軌下、枕下膠墊及道砟墊等不同隔振條件下軌道結(jié)構(gòu)動(dòng)力性能的變化。結(jié)果表明:軌下膠墊增加彈性后,可有效吸收車輪沖擊荷載和減少軌枕、道床的振動(dòng);枕下粘貼彈性膠墊后,鋼軌位移與軌枕振動(dòng)加速度有所增加,而鋼軌、道床的振動(dòng)加速度與軌座反力有一定程度的降低,有利于緩和列車對(duì)軌枕產(chǎn)生的附加沖擊動(dòng)力,提高碎石道床穩(wěn)定性;道床底部鋪設(shè)道砟墊后,鋼軌位移與道床振動(dòng)加速度有所增加,鋼軌振動(dòng)加速度與軌座反力則有一定程度的降低,路基面所承受壓力降低20%左右,在一定頻率范圍內(nèi)提高了軌道結(jié)構(gòu)對(duì)基礎(chǔ)的隔振效果。因此,多層隔振系統(tǒng)應(yīng)具體設(shè)計(jì)與合理配置,才能緩和其輪軌間劇烈的動(dòng)力作用。運(yùn)用軌道激振器與落軸沖擊等實(shí)驗(yàn)手段,結(jié)合室內(nèi)實(shí)尺軌道模型,形成包括改變軌枕類型、枕間距、扣件類型、軌下與枕下膠墊、道砟墊及道砟密實(shí)度等測(cè)試工況。通過變換激振器的激振頻率與落軸高度模擬列車不同速度,測(cè)試多種工況下輪軌作用力、鋼軌與軌枕的位移及振動(dòng)加速度、軌座反力等動(dòng)態(tài)響應(yīng)。分析試驗(yàn)結(jié)果表明:軌下基礎(chǔ)剛度較大,鋼軌振動(dòng)能量也較強(qiáng);增加軌枕質(zhì)量,在提高鋼軌振動(dòng)能量的同時(shí),使得軌枕振動(dòng)主頻有所下降;采用枕下墊或道砟墊,增加了軌道結(jié)構(gòu)整體彈性,降低了鋼軌自振頻率;設(shè)置輔助軌后,鋼軌主振頻率有所增加。測(cè)試信號(hào)功率譜和振動(dòng)傳遞函數(shù)的計(jì)算表明:軌下墊層彈性增加,鋼軌傳遞至軌枕的能量將減少;采用枕下膠墊后,由鋼軌傳遞至軌枕的振動(dòng)能量顯著增加,表現(xiàn)為軌枕振動(dòng)加速度增大,而道床吸收的振動(dòng)能量降低,對(duì)道床減振有利;鋪設(shè)道砟墊后,軌枕上較多的振動(dòng)能量傳遞至道床,有利于軌枕減振。InvestigationontheDynamicBehaviorofHigh-SpeedRailwayBallastTrackStructure(AbstractofthePh.D.Dissertation)ZHUJianyue,LIANSongliang(DoctorSupervisor)(KeyLaboratoryofRoadandTrafficEngineeringoftheMinistryofEducation,TongjiUniversity,Shanghai200092,China)Accordingtothepracticalsituationsofthenewly-builthigh-speeddedicatedpassengerlinesandtheexisting200km·h-1speed-increaserailwaylinesinChina,thestructureofballasttrackisstudiedintermsoftrackdynamicresponseanalysis,establishingtherailwaytrackFEMmodel,theinfluenceoftrackirregularity,thenumericalcomputationofwheelloaddrop,theperformanceanalysisofvariousisolationpads,theinvestigationonCWRvibrationcharacteristicthroughtheharmonicresponsewayandtheindoorfull-scalemodelexperiment.Withtheregularityofrailwaytrackalongitslongitude,aspatialFEMmodelisestablishedonthenumericalcomputationmethodoftrackelementwhichis0.6mlongasequalasonesleeperspacingandincludesthedynamiccharacteristicsofonesleeperaswellascorrespondingrailmass,fastening,pad,ballastandsubgrade.Inaddition,through“cuttingandmerging”timelyoneormoretrackelementsinthefrontandrearendofthevehicle,thedynamicresponseofaboundlesstrackcanbeinvestigated.ThecomparisonbetweenthetheoreticalcalculationandthetestresultsshowsthattheFEMmodelcanbeusedtoreflectthevibrationcharacteristicsoftrackstructure.Dependingonthetheoryofvehicle-trackcouplingdynamicsandthenumericalcomputationmethodoftrackelement,theinfluenceondynamicresponseofthewheel-railsystemexcitedbyrailsurfaceverticalshort-wavelengthroughnessinCWRweldjointwithheightdifferenceissystematicallydiscussedunderdifferentrunningvelocityaswellastrackirregularityamplitude,and,thevariationofdynamicbehaviorisdescribed.Thevariousshort-termwavelengthtrackirregularitiessuchasraggedweldjoint,gagelineshellycracksandrailsurfacescratchingwhichshouldbecancelledpromptlywouldintensifythewheel-rail′sinteractionobviouslyandacceleratetheballastcrushingwhichleadtotheballastaswellasthesubgradedifferentialsettlementandthetrackdeterioration.Moreover,itisfoundthatthetrackirregularityisthemajorreasonforproducingthewheel-raildynamicforcethroughtheanalysisonthevehicledynamiccharacteristicundervariousmedium-termandlong-termwavelengthtrackirregularityexcitationontheexisting200km·h-1speed-raisinglineswhichproposesthesuggestiononcontrollingtheirregularityamplitudeandformulatingthecriterionfortrackmaintenanceanditsirregularitymanagement.Toperfectthespatialrailwaytrackdynamicanalysis,theFEMmodelanalyzingtheharmonicresponseofCWRunderanaxiallyloadisdevelopedbasedonthemodesuperpositionwayaccordingtotheenergymethodandTimoshenkobeamtheory.TherelationshipbetweenthetemperatureforceandtheresonantfrequencyaswellasthecorrespondingamplitudevalueoftheCWRvibrationcharacteristicissimulatedandcalculatedthroughthemodelunderdifferentlongitudinaltemperatureforcesandrailwayparameters.Theresultsshowthattheresonantfrequencyincreaseswhileitscorrespondingamplitudedecreasesnonlinearlywiththetemperatureforce′sgrowingandthedifferentrailandsleeperspacingwouldaffecttheresonantfrequencytocertainextent.Basedonthevirtualdisplacementprincipalforsolvingthecontact-impactproblems,theequationsofvariationcalculatingthewheel-rail′scontactunderwheelloaddropisestablishedasitsdeterminedboundaryconditionsbeingreleasedaccordingtothepenaltyfunctionmethod.DependingonthecontactcontrolaswellasthetrackdynamicequationofFEMdeducedfromthepoint-to-surfacecontactelement,thedynamicresponseissimulatedandcalculatedforthehigh-speedrailwayballasttrackstructureimpactedbythefallingwheel-set.Theresultsshowthatthetrack′sdynamicresponse,inwhichtherail′saccelerationandrailchaircounterforcevarygreatly,increasesasthedropheightraises.Thevibrationofsleeperandballastisreducedasthepadsunderrailbecomemoreelastic.Therail′sdisplacementandsleeper′saccelerationincreasewhiletherailandballast′saccelerationandrailchaircounterforcedecreasewhentheelasticpadsappliedunderthesleepers.Additionally,thepressureonsubgradesurfacedecreasesabout20%andthefoundation′svibratingisolationisenhancedeffectivelyamongadefinitivefrequencyrangeaftertheballastpadsarepaved.Itisnotedthatthespecialdesignsshouldbemadeforisolationtracksonthebasisofthetrafficconditionsandrequirementstoalleviatethewheel-rail′sinteractionbyanalyzingthedynamiccharacteristicthroughapplyingdifferentvibrationisolationsundertherail,thesleeportheballast.Bythetrackvibrationexciterandfallingwheel-set,thedynamiccharacteristicsoftheindoorfull-scaletrackmodelareanalyzedintheworkconditionssuchaschangingthesleeperkind,thetiespacing,thefasteningtype,thepadsundertherailandthesleeper,theballastpads,theballastcompactnessandsoon.Theexciterfrequencyandwheelloaddropheightarechangedtosimulatethevehicle′sdifferentrunningspeed.Toevaluatetherailwaytrackdynamicperformance,thedynamicresponsessuchasthewheel-railforce,therailorsleeper′sdisplacement(andacceleration),therailchaircounterforceetc.aretestedandmeasured.Itisshowedthatthelargerthestiffnessundertherail,thestrongertherail′svibrationenergy