高速铁路级配碎石颗粒三维形态特征多尺度分析

Multi-scale analysis of three-dimensional morphological characteristics of graded gravel on high-speed railway

高速铁路路基级配碎石颗粒形态对宏观力学性质具有显著影响,合理量化颗粒三维形态特征是粗颗粒填料细观机制研究的基础性工作。采用激光扫描仪获取2.36~31.5mm粒径范围7个粒组共计700个碎石颗粒的点云数据,重构形成三维网格模型;引入描述颗粒表面凹凸特征的主曲率均值平方根RMS,基于颗粒网格模型平滑处理及RMS曲率分布特征,分别定义以棱角区域点云数量占比表征的棱角参数、以平滑前后模型RMS差异描述的纹理参数。结合长、中、短轴相互关系所描述的形状参数,形成刻画碎石颗粒多尺度形态特征的指标体系;通过选取典型形态特征颗粒,验证所建立的指标体系具有良好形态甄别能力;根据所扫描碎石颗粒的统计分析,不同粒组碎石颗粒的形状、棱角、纹理指标基本呈正态分布特征,随粒径增大,块状颗粒占比提高,棱角和纹理特征愈加突出。研究成果可为从宏、中、细观3个尺度量化评价颗粒形态特征提供参考。

The particle morphology of graded gravels of high-speed railway subgrade has a significant impact on the macro-mechanical properties.Reasonably quantifying the three-dimensional morphological characteristics of the particles is the basic work of the research on the micro-mechanism of fillers.Based on the laser scanner,the point cloud data of 700 gravel particles in 7 particle groups in the range of 2.36–31.5 mm are acquired.And these data are reconstructed to form three-dimensional grid models.By introducing the root mean square curvature(RMS)which describes the surface unevenness of the particles and considering the particle mesh model smoothing process and the RMS curvature distribution characteristics,the angularity parameters are defined by the proportion of the point cloud quantity in the edge area,and the texture parameters are defined by the difference of the model before and after smoothing.Combined with the shape parameters described by the relationship between the long,middle and short axes,the indexes system to describe the multi-scale morphological characteristics of gravel particles is formed.By selecting the particles with typical morphological characteristics,it is verified that the established index system has a good morphology discrimination ability.According to the statistical analysis of the scanned gravel particles,the shape,angularity and texture of the gravel particles in different groups basically present the characteristics of normal distribution.As the particle size increases,the proportion of block particles increases,and the angularity and the texture characteristics are more prominent.The research results can provide a reference for the quantitative evaluation of particle morphological characteristics from macro,medium and micro scales.