环氧沥青混凝土裂纹发展的三维可视化离散元模拟

Three-dimensional Visualization Discrete Element Modeling of the Crack Development of Epoxy Asphalt Concrete

为了在三维尺度下描述环氧沥青混凝土的裂纹发展行为,运用离散元程序PFC3D内置'Fish'语言,重构了环氧沥青混凝土非均质(集料、砂浆和空隙)多层次(矿料级配)结构三维虚拟试件,对虚拟试件微观组成成分之间的接触赋予了相应的微观接触模型,采用离散元方法实施了单边切口小梁虚拟三点弯曲试验,追踪并演示了微观裂纹的衍生发展全过程,并与室内数字摄像法捕捉的试件表面裂纹发展进行对比.研究结果表明:虚拟试验得到的宏观断裂力学响应与室内试验结果的吻合度较好,且虚拟试验结果的稳定性更优;三维离散元方法可以较好地模拟环氧沥青混凝土弯曲断裂过程中裂纹起裂与扩展行为,弥补了二维方法部分缺陷;基于离散元程序的追踪裂纹三维发展的模拟方法,可以作为研究沥青混凝土材料断裂特征的辅助手段.

In order to describe the crack development of epoxy asphalt concrete （EAC） from the three-dimensional （3D） scale perspective, a 3D virtual specimen of EAC with the heterogeneous （coarse aggregates, asphalt mastic and air voids） and multilayer （aggregate gradation） morphological features was first reconstructed by using the Fish language provided in the discrete element software PFC3D. Secondly, the corresponding micromechanical models describing the interaction of micro-scale components of the virtual specimen were assigned. Finally, a single-edge notched beam virtual three-point bending test was imple- mented by using the discrete element method （DEM）. The progressive development of microcrack trajecto- ries was tracked and visualized, and the simulation results were compared with the surface crack development of specimens captured in a digital camera method. The results have indicated that the macro fracture responses of virtual test show generally good agreement presents better stability than the laboratory test. Addit with the experiment results, and the virtual test ionally, the three-dimensional DEM developed is capable of simulating the initiation and propagation of cracks during the bending fracture of EAC, thus im- proving the two-dimensional （2D） method. Furthermore, it has been found that the method based on the DEM program, which is used to illustrate the development of 3D cracks, can be used as a supplemental tool to investigate the fracture behavior of EAC.