Degradation of railway ballast aggregate is ensued from breakage of single particle as well as from abrasion of angular corners. The present study evaluates the change in morphological characteristics as well as particle size distribution of ballast aggregate degraded under applied impact loads to further illuminate the degradation mechanism of particles. The utilized drop-weight impact loading apparatus implemented on prepared ballast specimens is modified to take into account the real stress levels applied over ballast course. The morphological features of aggregate including angularity and surface roughness are quantified by establishment of extended image processing method. Generally, the obtained results uphold the evident effect of parent rock type on degradation mechanism. Also, the percent reduction of indices related to angularity and surface roughness are in line with increment of degradation level measured by fouling index (FI). Furthermore, the change in morphological indices is not significant in case of using particle size distribution with higher uniformity coefficient compared with more uniform gradation. Indeed, major effect of selection of broader sieve size range is exhibited on reduction of breakage of larger-sized aggregate. Meanwhile, provision of flexible subgrade instead of rigid type considerably diminishes the percentage of reduction of sharp corners and surface roughness which confirms evident effect of stiffness of underlying layer on level of abrasion of coarse particles.

单个颗粒的破损以及角angular的磨损会导致铁路压载骨料的降解。本研究评估了在施加冲击载荷下降解的道ball骨料的形态特征以及粒径分布的变化，以进一步阐明颗粒的降解机理。修改了在准备的压载样品上使用的落锤冲击加载设备，以考虑到压载层上施加的实际应力水平。通过建立扩展的图像处理方法，可以量化聚集体的形态特征，包括角度和表面粗糙度。通常，所获得的结果支持母岩类型对降解机理的明显影响。也，与成角度和表面粗糙度有关的指数降低的百分比与由结垢指数（FI）测得的降解水平的增加一致。此外，在使用具有更高均匀度系数而不是更均匀灰度的粒度分布的情况下，形态学指标的变化并不明显。实际上，选择较宽的筛子尺寸范围的主要效果表现在减少较大尺寸的骨料的破碎上。同时，提供柔性路基而不是刚性路基可大大减少锐角和表面粗糙度的减少百分比，这证实了下层的刚度对粗颗粒的磨损水平具有明显的影响。与使用更均匀的渐变相比，如果使用具有更高均匀度系数的粒度分布，形态指标的变化并不明显。实际上，选择较宽的筛子尺寸范围的主要效果表现在减少较大尺寸的骨料的破碎上。同时，提供柔性路基而不是刚性路基可大大减少锐角和表面粗糙度的减少百分比，这证实了下层的刚度对粗颗粒的磨损水平具有明显的影响。与使用更均匀的渐变相比，如果使用具有更高均匀度系数的粒度分布，形态指标的变化并不明显。实际上，选择较宽的筛子尺寸范围的主要效果表现在减少较大尺寸的骨料的破碎上。同时，提供柔性路基而不是刚性路基可大大减少锐角和表面粗糙度的减少百分比，这证实了下层的刚度对粗颗粒的磨损水平具有明显的影响。