基于离散元法的沥青混合料细观特性分析

Microstructure characteristics analysis of asphalt mixture based on the discrete element method

为了从细观上模拟分析沥青混合料车辙的形成和发展机理,以双层车辙试件为研究对象,采用PFC2D,建立上层为SMA-13,下层为AC-20,包含粗集料、沥青砂浆和空隙的二维离散元模型,研究了试件内部接触力的分布与大小、集料的空间运动轨迹对车辙形成的影响;分析了不同工况下车辙试件内部接触力大小分布和空间运动轨迹,结果表明:SMA-13主要承受压应力作用,拉应力主要分布在AC-20面层,且更容易导致试件发生破坏,加载2h时,AC-20拉应力较1h时增大3~4个数量级;SMA-13级配骨架性好,在荷载作用下主要发生水平运动,AC-20级配骨架性较弱,集料、砂浆易发生垂直运动,导致车辙形成.

To analyze the formation and development mechanism of asphalt mixture rutting from the mesoscopic level,taking double-layer rutting specimens as research object,the PFC2 D was used to build a two-dimension model with the upper layer of SMA-13 and the lower layer of AC-20,including void,asphalt mortar and coarse aggregate,to study the effect of the distribution and size of the internal contact force on the rutting formation.The distribution of contact force and spatial motion trajectory in the internal rutting specimens under different working conditions were analyzed.The results shows that SMA-13 is mainly subjected to compressive stress,and the tensile stress is mainly distributed in the AC-20 surface layer,which more easily lead to the destruction of the specimen.When loading for 2 h,the tensile stress of AC-20 increases three to four orders of magnitude more than that for 1 h.The SMA-13 grade skeleton has good performance,and the main motion under the load is horizontal.While the AC-20 grade skeleton has bad performance,the aggregates and mortar tend to have vertical movement and lead to the occurrence of rutting.