细观尺度下大孔隙环氧沥青混合料损伤演化分析

Analysis of Damage Evolution in Heterogeneous Porous Epoxy Asphalt Mixture Based on Micro-Scale

通过数字图像技术获取了大孔隙环氧沥青混合料的多相细观结构,建立了包含集料、沥青砂浆、空隙在内的细观结构有限元仿真模型,引入了内聚力模型,通过劈裂试验数值模拟,对内部结构应力响应、裂纹扩展及损伤演化过程进行了分析.研究结果表明:空隙、集料等细观结构的不均匀分布,对混合料的应力响应及其分布均造成一定影响;劈裂试验模拟过程中,损伤变量D值达到1时,试件开始启裂,预设内聚力单元模拟的启裂位置与室内试验观察较为一致,而后裂缝开始扩展,但扩展速率逐渐变小;双线性内聚力模型较好地模拟了混合料损伤规律与裂纹启裂、扩展路径.

The digital image processing was used to capture the microstructure, and the finite-element model including the aggregate, sand mastic and air voids was established. The simulations were performed to investigate crack evolution under monotonic loading using a bilinear cohesive zone model. Results show that the inhomogeneous distributions of the aggregates and the air voids have some influence on the stress distribution. When the damage variable （D） increases to 1, the crack initiation will occur, and there are great agreements between the crack initiating location of simulation and that of experiment. The growth rate of the crack quantities decreases with the crack propogation occuring. The bilinear cohesive zone model can simulate the damage evolution, crack initiation and propagation well.