沥青混凝土复合型裂纹扩展行为数值模拟

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1、第23卷第10期公路交通科技Vol.23No.102006年10月JournalofHighwayandTransportationResearchandDevelopmentOct.2006文章编号:1002-0268(2006)10-0020-05沥青混凝土复合型裂纹扩展行为数值模拟1,21毛成，邱延峻(1.西南交通大学土木工程学院,四川成都610031;2.四川省交通厅公路规划勘察设计研究院,四川成都610041)摘要:应用线弹性断裂力学有限元程序,对一系列沥青混凝土偏直裂纹的扩展路径依据标准的三点弯曲梁试件解析。结果表明,随着预制裂纹偏离梁中线距离的增加,裂纹

2、的起裂角和峰值荷载都增大。当集中荷载一定时,预制裂纹越长,应力强度因子越大;当预制裂纹长度与梁高比率a/W为0.4时,裂纹起裂角最大。I型应力强度因子和裂纹起裂角与比率a/W之间可分别用三次多项式很好地拟合。裂纹扩展路径总体上遵循一定的规律。试验结果表明,由于沥青混凝土材料颗粒的不均匀性,裂纹扩展路径通常沿着集料颗粒边界扩展而很少切断颗粒。虽然裂纹尖端处于I-II复合型应力状态下,但拉应力仍然是裂纹扩展的主要驱动力。关键词:道路工程;沥青混凝土;复合型裂纹;三点弯曲法;扩展路径;数值模拟中图分类号:U414.75文献标识码:ANumericalSimulationof

3、CompoundCrackPropagationBehaviorofAsphaltConcrete1,21MAOCheng,QIUYan-jun(1.SchoolofCivilEngineering,SouthwestJiaotongUniversity,SichuanChengdu610031,China;2.SichuanProvinceCommunicationsDepartmentHighwayPlanningSurveyDesignandResearchInstitute,SichuanChengdu610041,China)Abstract:Bymeans

4、offiniteelementprogrambasedonlinearelasticfracturemechanics,thecrackpropagationpathsofaseriesofasphaltconcretearesimulatedbasedonstandardthreepointbendingbeamspecimenanalysis.Theresultsshowedthatthecrackinitiationangleandthepeakloadincreasedasthedistanceofthepreexistingcrackfromthemidpo

5、intofthebeamincreased.Whileconcentratedloadisconstant,thelongerthepreexistingcrackis,thehigherthestressintensityfactor(SIF),andcrackinitiationanglewouldbeuptomaximumwhentheratioofthelengthofpreexistingcrackandtheheightofbeama/Wequalsto0.4.TherelationshipbetweentheSIFoftypeIandtheratioa/

6、Wcanbefittedwellbythree-orderpolynomial,also,thesimilarrelationshipisfoundbetweencrackinitiationangleandtheratioa/W.Thecrackpropagationpathfollowssomeregularityonthewhole.Theexperimentalresultsshowedthatthecrackpropagationpathwouldmainlyfollowtheboundariesofthegrainsandrarelycutthrought

7、hegrains,andthesedifferencescouldbeattributedtothegrainsizeeffectinasphaltconcrete.Althoughthestressfieldofcracktipischaracteristicofmixedmode,themainforcetocausecrackpropagationisstilltensilestress.Keywords:roadengineering;asphaltconcrete;compoundcrack;threepointbendingmethod;