基于粗集料形状特征的沥青混合料三维数字试件生成

Generation of three-dimensional digital specimen of asphalt mixture based on coarse aggregate shape characteristics

为了准确地模拟沥青混合料相关试验,节省集料和试验设备等方面的成本,通过离散单元法模拟生成沥青混合料三维数字试件.采用中心球扩散方法构建出粗集料的扁平比与棱角性,通过调节不同粗集料模型的百分比来获得和实际相近的粗集料形状组合,并用一定质量的虚拟粗集料"clump"球体块取代同样质量的等效球体来表征粗集料级配特征,通过删除砂浆球体单元来模拟出空隙率特征,最终建立沥青混合料三维离散元模型.研究表明,沥青混合料三维数字试件可以很好地模拟粗集料的三维空间形状,准确表征粗集料的扁平比与棱角性特性,同时能够精确显示粗集料的级配特点与空隙分布,达到以虚拟试件代替真实试件进行试验的目的.

For the purpose of accurate simulations of the asphalt mixture tests and saving costs in aggregate consumption and testing equipments,a three-dimensional digital specimen of asphalt mixture was simulated by the discrete element method. The flatness and angularity were simulated by the diffusion method based on a central sphere. The coarse aggregate shape combinations which are close to the fact were obtained by adjusting percentage of different coarse aggregate models. To simulate the gradation characteristics of coarse aggregate,a certain quality of coarse aggregate＂clump＂was used to replace the equivalent sphere of the same mass. The void fraction was simulated by removing the unit of mortar sphere. Thus,the three-dimensional discrete element model of asphalt mixture was established. The results show that the three-dimensional digital specimen can accurately simulate the three-dimensional shape of coarse aggregate,and reflect the features of the flatness and angularity well. Meanwhile,the gradation characteristics and the void distribution of coarse aggregate can be precisely displayed. Therefore,the virtual specimen can replace the real specimen for testing.