关键词: 冻融, 边缘检测, 分型理论, 显著性分析

Abstract: The deterioration of the physical properties of loess under freezing and thawing conditions is one of the concerns that must be taken into consideration when construction in the cold regions. In this paper, a variety of loess samples with different water contents were taken from Huangling County of Yan'an Prefecture as research objective to further study the physical change of the loess while exposing in freezing-thawing environment. The microstructure alternations of loess under freezing and thawing condition were evaluated by means of scanning electron microscope, edge detection and quantitative classification; the correlationship between the moisture content of the samples and various freezing-thawing cycles were revealed, as well as the changes of strength index of the samples through GDS and its degree of significance. The results showed that the grain fracture grows with the increase of freezing thawing cycles, the large particles are continuously broken down into smaller particles, the skeleton connection mode changes from surface to surface contact to point to point contact; with the increase of the number of freezing-thawing cycles, the fractal dimension increases; after 10 freezing-thawing cycles, the porosity and fractal dimension tend to be stable; with the increase of freezing-thawing cycles, the cohesion of the sample decreases, the internal friction angle increases continuously, and the strength index tends to be stable after 10 freezing and thawing cycles. The experimental results are consistent with the scanning results of SEM; by analyzing the cohesion and internal friction angle of specimens, it can be seen that the freezing-thawing cycles, initial water content and their interaction (coupling action) have particularly significant effects on the strength index of the samples.

Key words: freezing-thawing, edge detection, fractal theory, significance analysis