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Climate change brought about significant freeze-thaw (FT) deformation of clayey soils distributed in cold regions, which resulted from soil structure evolution including pore size distribution change and crack development. However, the formation of clay aggregate that dominates the soil deformation behavior during FT remains unclear. This study investigated the effects of clay contents (5 %, 10 %, 15 %, and 20 %) and subfreezing temperatures (-5 degrees C, -10 degrees C, and -15 degrees C) on the soil FT deformation properties by isotropic isothermal FT tests. Meanwhile, the soil structure evolution was characterized via Nuclear Magnetic Resonance and X-ray Computed Tomography. The results indicated that the frost heave ratio (eta) and thaw settlement coefficient (delta) non-linearly varied with clay content and subfreezing temperature. Specifically, the minimum eta and delta were observed in the specimen with 10 % clay content, and the maximum eta and delta were identified at -10 degrees C. This phenomenon can be attributed to the clay aggregate forming bimodal or unimodal pore size distribution (PSD) with different initial clay contents. The freezing characteristics of inter- and intra-aggregate pore water were determined by the solidwater interaction. Moreover, the FT action altered the structure of clayey soil by the change in PSD and the generation of cracks. The contribution of pore size change and crack development to the total volume change before and after FT was quantitatively analyzed. It demonstrated that pore size change was more important for the total volume change in specimens with lower clay content and higher subfreezing temperature, whereas crack development mainly contributed to the total volume change in the rest of the specimens. This study provides a deep insight into the deformation characteristics of clayey soils under different climate conditions in cold regions.

期刊论文 2024-04-30 DOI: 10.1016/j.catena.2024.107916 ISSN: 0341-8162
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