冲积层砾石颗粒形态特征及其堆积特性

Gravel particle morphology and accumulation characteristics of alluvial layer

砾石颗粒的二维形态特征与颗粒堆积力学特性之间具有显著的关联性.以河流冲积层2-50mm的圆砾石粒径组为主要对象,利用数字图像技术,通过对大样本圆砾颗粒的形态特征分析,选取轴向系数为圆砾的形状特征参数,建立二维圆砾椭圆模型数据库,提出圆砾颗粒的二维椭圆模型构建方法,进而通过PFC2D堆积试验分析了单粒组圆砾料的堆积特性,得出以下结论:(1)圆砾石整体形态特征与标准圆在整体上差异较小,无显著棱角性和不规则性;(2)基于变异系数表征了形态参数对于颗粒形状的敏感程度,选取轴向系数评定颗粒二维形态特征参数;(3)砾石粒径组粒径越小,棱角性越明显,形状越不规则,孔隙率越大.

There is a significant correlation between the two-dimensional morphological characteristics of gravel particles and the mechanical properties of particle packing.Taking the gravel particle size group of 2-50mm in the river alluvial layer as the main object,using digital image technology,by analyzing the morphological characteristics of large samples of gravel particles and selecting the axial coefficient as the shape characteristic parameter of the gravel,a two-dimensional gravel ellipse model database was established and a reconstruction method of the two-dimensional equivalent ellipse model of gravel particles was proposed.The accumulation characteristics of the single group of gravel materials were analyzed with the PFC2D test.The following conclusions are drawn:(1)The overall shape characteristics of gravel are not different from the standard circle,with no significant angularity and irregularity;(2)As the coefficient of variation characterizes the sensitivity of the morphological parameters to the particle shape,the axial coefficient can be(3)The smaller the particle size group,the more obvious the angularity,the more irregular the shape,and the greater the porosity.