Molecular dynamics simulation of deformation and failure mechanism of kaolinite at different temperatures
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摘要: 在不同温度条件下,运用分子动力学方法对高岭石OA、OB、OC三个方向进行单轴拉伸模 拟,从微观角度还原高岭石变形及破坏的过程,研究了高岭石在不同温度下的微观结构变化、拉伸 过程中的变形机理以及拉伸力学性能的温度效应。 结果表明,弛豫后的高岭石随着温度升高产生 热膨胀;沿OA和OB方向的拉伸,一旦裂纹形核出现,裂纹将会快速扩展,从而导致应力急剧下降, OC方向在拉伸过程中会出现整层分离的现象,构型将随着氢键作用的消失而发生破坏。 高岭石力 学性能对温度具有很强的依赖性:抗拉强度、杨氏模量与温度呈负相关关系;随温度升高,拉伸极限 应变和残余强度呈降低的趋势,强度衰减系数呈增加的趋势,OC方向受温度影响最大,OB方向次 之,OA方向最小。Abstract: UniaxialtensilesimulationswerecarriedoutinOA,OBandOCdirectionsofkaoliniteatdifferent temperaturesbyusingmoleculardynamicssimulations*Thedeformationandfailureprocessesofkaolinite werestudiedattheatomisticscale*Thechangeofmicrostructure,deformationmechanismandtemperature effectoftensilemechanicalpropertiesofkaoliniteatdifferenttemperatureswerealsoanalyzed*Thiswork wouldbehelpfultounderstandthemechanismsoflargedeformationandfailureofsoftrock*Theresultsindi⁃ catedthattheincreasingoftemperatureresultsinthethermalexpansionofkaoliniteafterrelaxation*Once thecracknucleationappears,itpropagatesveryquicklyandleadstoasharpdecreaseinstressalongOAand OBloadingdirections*ThelayerseparationoccursduringloadingalongOCdirection,whilethestructure couldfailsincethehydrogenbondsarebroken*Themechanicalpropertiesofkaolinitehaveastrongdepend⁃ enceontemperature*Thereisanegativecorrelationbetweentensilestrength,Young*smodulusandtempera⁃
ture*Withtheincreaseoftemperature,thetensileultimatestrainandresidualstrengthtendtodecrease,and thestrengthattenuationcoefficienttendtoincrease*Inaddition,OCdirectionisthemostaffectedbythetem⁃ perature,followedbyOBdirection,andOAdirectionistheleastaffected*
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