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摘要: 采用离散元方法构建了沥青混合料马歇尔数字试件, 模拟了间接拉伸试验, 研究了粘结强度比、颗粒摩擦因数和加载速率对微裂缝扩展过程的影响, 分析了试件内部颗粒的细观响应。模拟结果表明: 粘结强度比越大, 沥青的粘结特性越明显, 使得微裂缝的类型由法向渐变为切向, 当粘结强度比由0.500增大到4.000时, 接触力减小了78.05%, 位移减小了78.57%;摩擦因数的增大, 提高了集料的粗糙度, 当摩擦因数由0.3增大到0.7时, 接触力增大了31.21%, 位移减小了21.45%, 但其对微裂缝的分布影响不大, 主要为法向微裂缝; 当加载速率由0.03mm.s-1增大到0.07mm.s-1时, 接触力增大了3.50%, 微裂缝的类型、数量与位移大小基本不变, 相比沥青和集料, 加载条件对微裂缝扩展的影响很小。Abstract: Marshall numerical specimens of asphalt mixture were made by using discrete element method, indirect tensile test was conducted, the influences of parallel-bond strength ratios, particle friction coefficients and loading velocities on micro-crack extension processes were studied, and the mesomechanics responses of particles in the specimens were analyzed.Simulated result indicates that the bonding characteristics of asphalt are more obvious when the parallel-bond strength ratio is larger, which makes the types of micro-cracks change from normal micro-cracks to tangential micro-cracks.When the ratio changes from 0.500 to 4.000, the contact force reduces by 78.05%, and the displacement reduces by 78.57%.The roughness of aggregate increases with the increase of friction coefficient.When the coefficient changes from 0.3 to 0.7, the contact force increases by 31.21%, and the displacement reduces by 21.45%, but there is little effect on the distribution of micro-cracks that are mainly normal micro-cracks.When the loading velocity changes from 0.03 mm·s-1 to 0.07 mm·s-1, the contact force increases by 3.50%, and the types and numbers of micro-cracks and the amounts of displacements do not change basically.Loading conditions have less effect on micro-crack extension compared with asphalt and aggregate.
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Table 1. Material parameters
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