Abstract:

This study aims to further reveal the deterioration mechanism of subgrade soil performance under the coupling of multiple factors. On the basis of previous work, CT scanning technology is adopted to analyze the mesoscopic structural characteristics of compacted silty clay under wetting-drying cycles sequentially coupled with dynamic loadings. By examining influences of the coupling effect on the three-dimensional spatial pore distribution, the statistical distribution of pore volume, and the statistical indicators of image grayscale, the relationship between the macroscopic performance and the mesoscopic structural characteristics of specimens is revealed. Results indicate that more large pores and through-cracks would be induced by wetting-drying cycles, while part of pores or cracks caused by wetting-drying cycles can be closed by dynamic loadings. With the sequential coupling of wetting-drying cycles and dynamic loadings, the number of small pores in the specimen tends to increase. Increasing of total pore volume can be caused by wetting-drying cycles, and decreasing of total pore volume can be caused by sequential dynamic loadings. The mesoscopic structural parameters can be used to explain the evolution of macroscopic performance of specimens.

Key words: CT, wetting-drying cycle, dynamic loading, sequential coupling effect, subgrade soil, mesoscopic structure