铁路小半径曲线钢轨病害成因与整治分析——以昆明工务段南昆线为例

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1、万方数据北京交通大学硕士专业学位论文摘要(7)给轨头施加足够大的垂向和横向轮轨力，当轮轨接触面边缘处于裂纹尖端正上方且接触面位于未开裂-N时，水平裂纹向斜上方扩展，最后发展成为剥离掉块。而当其处于开裂一侧时，水平裂纹朝轨头中心且略微向下方发展，进一步扩展成为斜裂纹，甚至出现核伤和断轨。研究结论与现场观察结果一致。(8)水平裂纹尺寸较小时，除了裂纹尖端应力及应变较大外，轨头其他部位应力、应变变化不大。只有当裂纹发展到较大尺寸或向纵深发展时，改变轨头有效截面大小，才有可能发生断轨。因此，轨头出现小尺

2、寸的水平裂纹时，钢轨仍然处于安全状态，但要定期观察裂纹的扩展现象。水平裂纹及其他形式的裂纹允许的最大安全尺寸还要结合实际做进一步的研究与现场试验。关键词：钢轨；小半径曲线；剥离掉块；水平裂纹；仿真计算万方数据北京交通大学硕士专业学位论文ABSTRACTABSTRACTBecauseofthelowdesignstandard，longservicelife，badgeologyandclimateofexistingrailwaysinmountainousregions，alsowiththe

3、improvingrunningspeed，increasesofgrossrailloadonaxleanddensityoftrafficflow,applicationofhigh·strengthandgood-wear-resistancerail．shellingdefectsofrailheadandhorizontalcrackshavebecomethemaindamagesofsmall．radiuscurvetracks．Whenatrainrunsthroughasmal

4、l—radiuscurvetrackwithhighspeed，thelateralrailheadwillsufferfromeccentriccompressioneasily,andthesub-surfaceofthemedialsidewillyield，bothofwhichcausethegrowthoffatiguecracks．Moreseriously,themedialrailheadwilloccursshellingdefects，leadingtoirregularr

5、ollofwheelswhichwillcontributetoextensionofthedamagesorevenraildisjunction．Hence，thisthesistakestheNanning-KunmingRailwayofKummingTrackMaintenanceDivisionasanexampletostudyandsolvetheraildamagescausedbyrollingwheels．Thisresearchmakesagreatsensetoimpr

6、ovethesafeoperationofrailwaysinmountainousregions．Takethe400-metersmall-radiuscurvetrackofNanning-KunmingRailwayZHK707+732．4asresearchobject，wefirstconductafieldinvestigation．Thencombinedwiththedailymaintenancedata，summarizethecausesandlawsofdevelopm

7、entofrailheadonthecurverails．Withtheparametersofsmall．radiuscurvetracksacquiredfromthescene，applySIMPACKtoconductdynamicscomputationandoptimizethegeometricparametersofthecurvetracks．ThenapplytheextendedfiniteelementmoduleofABAQUS／XFEMtoanalyzethelaws

8、ofgrowthanddevelopmentoflateralcracks．Throughthisresearch，wecanarriveatthefollowingconelusions．(1)Thereisacausalitybetweenlateralcracksandshellingdefectsthatshellingdefectsofrailsgrowoutoflateralcracksofrailheads．Hence，studyingthelateralcracksofrailh