基于内聚力模型的沥青混合料劈裂试验模拟

Simulation of indirect tension test of asphalt mixtures based on cohesive zone model

为了深入分析沥青混合料在荷载作用下的破损机理,引入了内聚力模型.使用双线性内聚力模型模拟了沥青混合料劈裂试验过程,比较并分析了数值模拟结果和试验结果,研究了劈裂试验过程中试件纵轴上的法向应力分布、损伤规律以及裂缝的形成和扩展情况,描述了劈裂试验的全过程.结果表明:双线性内聚力模型数值模拟结果和试验结果相当吻合,因而可以用来模拟沥青混合料的损伤断裂行为;劈裂试件纵轴上两端为压应力,中间为拉应力,且试件两端产生了显著的压应力集中;试件纵轴上的损伤值和损失长度随着荷载的增加而增加;纵轴中间的损伤值达到1时,试件中就会产生一定长度的宏观裂缝,而后裂缝向两端扩展,但扩展速率逐渐减小.

The cohesive zone model was introduced to analyze the damage mechanism of asphalt mixtures.The process of indirect tension test of asphalt mixtures was simulated using a bilinear cohesive zone model.The numerical simulation result and the test results were compared and analyzed.The normal stress distribution,damage law and the crack initiation and propagation on the longitudinal axis of the test sample was studied.The whole process of indirect tension test was described.The study indicates that the numerical simulation result and the test results agree very well so that the bilinear cohesive zone model is applicable to simulate the fracture behavior of asphalt mixtures.Compressive stress lies on the two ends of the longitudinal axis of the test sample,the tensile stress lies on the middle part and the two ends undergo significant compressive stress concentration.The damage value in the damaged zone on the longitudinal axis increases with the load increase and the length of the damaged zone also increases.When the damage value in the damaged zone increases to one,a certain length of macro-crack emerges in the test sample and then the crack extends to both ends with the growth rate slowing down gradually.