建立高效的三维集料重构方法是开展沥青混合料虚拟实验的必要前提.利用3D激光扫描仪采集500颗集料的点云数据,经正二十面体剖分简化后通过球谐函数表征其三维形态.分析集料的体积、表面积、形状指数FI、棱角性指数AI随点云数量与球谐阶数的变化规律,确定点云的简化标准.计算简化集料10阶球谐系数,得到121个球谐系数的累积分布曲线,根据分布特性采用 Monte Carlo方法随机生成1 400组球谐系数,实现集料的几何重构,对比真实集料与虚拟集料AI、FI的分布特性,验证重构方法的有效性.结果表明:可采用642个数据点与10阶球谐函数实现集料的有效简化;虚拟集料的FIv、AIv分布范围均可包含真实集料的参数值.研究成果可以为沥青混合料的细观模型构建提供基础.
Simplification and Reconstruction of 3D Aggregates Based on Spherical Harmonic Function
Establishing an efficient three-dimensional aggregate reconstruction method is a crucial precondition for conducting virtual experiments on asphalt mixtures.Point cloud data of 500 aggregates were collected by using a 3D laser scanner.The 3D shapes of data were represented using spherical harmonics after simplification through icosahedral subdivision.The relationships between the number of point clouds,spherical harmonic orders,and aggregate characteristics such as volume,surface area,shape index(FI),and angularity index(AI)were analyzed to determine the simplification criteria for the point clouds.The 10th-order spherical harmonic coefficients of the simplified aggregates were calculated,yielding a cumulative distribution curve of 121 spherical harmonic coefficients.Based on the distribution characteristics,the Monte Carlo method was employed to randomly generate 1,400 sets of spherical harmonic coefficients,achieving the geometric reconstruction of the aggregates.The distribution characteristics of AI and FI for the real and virtual aggregates were compared to verify the effectiveness of the reconstruction method.The results indicate that 642 data points and 10th-order spherical harmonics can effectively simplify the aggregates.The distribution ranges of FIv and AIv for the virtual aggregates encompass the parameter values of the real aggregates.These research results provide a foundation for constructing micromechanical models of asphalt mixtures.
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