The lack of researches on the intrinsic microstructure evolution of coarse-grained soil fillers during subgrade compaction-operation period (SCOP), resulting in a deficiency of theoretical guidance for the lifecycle health monitoring of high-speed railway subgrade. In this paper, the self-developed intelligent vibratory compaction instrument (IVCI) was used to rapidly simulate the loading action on high-speed railway gravel aggregate (HRGA) during SCOP. Additionally, two physical-mechanical indicators, dry density rho d and dynamic stiffness Krb, were used to characterize the physical-mechanical properties of HRGA fillers. Besides, the microstructure (coarse particles and voids) evolution within the HRGA fillers during SCOP were in-depth explored based on X-Ray computed tomography (X-CT) technology. The results indicate that the rho d exhibits a continuous slow increase trend, but the Krb exhibits distinct deteriorating characteristics, with a consistent gradual decline after compaction periods. The particle rearrangement is crucial in the compaction periods of HRGA fillers, and the optimal compaction level (referred to the locking point) can be determined by the particle rearrangement indicator Hr. Besides, the particle local shape indicators (angularity coefficient and contour coefficient) as well as void local shape indicator (abundances) can used to explain the deterioration characteristics of HRGA fillers during operation periods. It is important to note that under the vibratory loading, insufficient crushing occurs at the particle corners within the internal skeleton, decreasing the stability of skeleton and giving rise to the content of fine particles, which can fill up the large-sized voids and generate a significant number of morphologically flawed middle-sized and small-sized voids. The finding of this research not only provide a refined analysis and insight understanding of the construction and operation of high-speed railway subgrade, but also can contribute to establishing a solid theoretical foundation for the lifecycle health monitoring of subgrades.

为了探索冻土正融过程中CT图像灰度值随时间变化的特点。将-27℃的冻土试样放置在20℃的室温环境中依靠与空气自然对流加热融化,同时连续地进行CT扫描,得到各时刻的CT灰度图像,并记录温度-时间变化曲线。通过对试样各个时刻CT图像平均灰度值的统计,得到CT图像的时间-灰度变化曲线,并与试样的时间-温度变化曲线进行对比。结果表明:在冻土温度上升和融化过程中灰度均值随时间呈明显上升趋势。在冻土完全融化后,虽然温度继续上升,但灰度均值基本不发生变化。因此,在冻土融化完成时刻,在时间-灰度图像上出现一个明显的折点,该折点可以视为冻土融化完成的标志。