基于构型力断裂准则的骨料干涉作用分析

Analysis of Aggregate Interaction Based on Configuration Force Fracture Criterion

为研究沥青混凝土内部裂纹初始构型(如裂纹初始偏转角,空间位置)的改变对裂纹扩展路径以及裂纹扩展方式的影响,以裂尖构型力为断裂准则,通过扩展有限元XFEM建立具有不同初始构型的裂纹模型,模拟裂纹经过单骨料和非对称双骨料的情况;从裂纹扩展路径和裂尖构型力变化等方面分析骨料干涉作用下裂纹初始构型对裂纹扩展的影响.结果表明:1)在单骨料干涉作用下,裂尖构型力随骨料与初始裂尖夹角的增大而逐渐增大,表明骨料对裂纹扩展的干涉作用逐渐减弱,当其超过60°后,骨料对裂纹扩展的干涉作用可忽略不计;2)在非对称双骨料干涉作用下,随着骨料圆心连线与x轴夹角的增大,双骨料对裂纹扩展干涉作用愈加明显,当其大于45°时,裂尖构型力明显偏小,即骨料对裂纹扩展表现出“止裂”效果;3)当裂纹初始偏转角发生改变时,单骨料与非对称双骨料对裂纹扩展的干涉作用具有相似性,其裂尖构型力随偏转角增大呈现先增加后减小的趋势;4)当偏转角为45°时,裂尖构型力偏大,意味着裂纹趋于非稳定状态,骨料对裂纹扩展的抑制效果较弱,致使骨料对沥青混合料抗裂性能的提高受到一定限制.

In order to study the influence of the initial crack configuration(such as the initial crack deflection angle and the space position)in asphalt concrete on the change of crack propagation path and growth mode,A crack model with different initial configurations was established by extended finite element XFEM with configuration force at crack tip as fracture criterion to simulate the crack propagation through single aggregate and asymmetric double aggregate.The influence of initial crack configuration on crack propagation was analyzed from the aspects of crack propagation path and crack tip’s configurational force.The results are summarized below:1)Under single aggregate interference,the crack tip’s configurational force gradually increases with the increase of the angle(the angle between the line connecting the crack tip and the center of the aggregate and the x-axis),indicating that the interference effect of the aggregate on the crack propagation gradually weakens.When the angle is over 60°,the interference effect of aggregate on crack propagation is negligible;2)Under the interference of asymmetric double aggregate,as the angle(the angle between the line connecting the center of the aggregate and the x-axis)increases,the aggregate interference effect on crack propagation gradually enhances.When the angle is over 45°,the crack tip’s configurational force is significantly smaller,that is,the aggregate exhibits a“crack arresting”effect on the crack propagation;3)When the initial crack deflection angle changes,the interference effect of single aggregate and asymmetric duel-aggregate on crack propagation is similar.The crack tip’s configuration force increases first and then decreases with the increase of deflection angle;4)When it is equal to 45°,the larger crack tip’s configurational force means that the crack tends to be in an unstable state,and the inhibitory effect of the aggregate on crack propagation is weak;hence,the improvement of the crack resistance of the asphalt concrete by the aggregate is limited.