关键词: 水泥土, 冻融循环, 三轴试验, 裂隙特征, 微观形态

Abstract: In the aim of understanding the changes of cement-reinforced silty soft soil under freeze-thaw cycles, we conducted triaxial compression tests, CT scanning, and SEM scanning on cement-soil specimens undergone 0-10 times of cyclic freezing and thawing to examine the mechanical properties and microstructural damage of soil specimens. Results revealed that the stress-strain curves of cement-soil displayed strain hardening features. With the increase of freeze-thaw cycles, the cohesion and internal friction angle shrank in exponential and linear trends, respectively. Binary results of CT scanning images manifested that the crack rate rose exponentially with the increase of freeze-thaw cycles. During cyclic freezing and thawing, the change of fracture rate synchronized with those of strength indicators. Moreover, from SEM scanning we observed losses of cementitious agents in the cement-soil and decay of compactness among particles, which led to the expansion of cracks and degradation of mechanical properties.

Key words: cement-soil, freeze-thaw cycles, triaxial test, fracture characteristic, microstructure