Reliable characterization of freeze–thaw-induced structural change is essential for evaluating compacted soils used in cold-region engineering, where repeated freezing and thawing can alter both surface integrity and internal pore structure. This study combines digital imaging, quantitative crack analysis, and X-ray computed tomography to characterize structural changes in compacted expansive soil subjected to 0, 1, 4, 7, and 10 freeze–thaw cycles. Specimens with initial water contents of 18% and 25% were observed during freezing and after thawing, while the post-thaw three-dimensional pore structure of the 18% specimen was reconstructed from CT images. The 18% surface specimen exhibited no continuous crack network despite evident internal pore restructuring, whereas the 25% specimen showed pronounced crack opening during freezing and partial closure after thawing. With increasing cycles, the crack pattern evolved from a dominant wide crack to a branched network of narrower cracks and then became less continuous. CT-resolvable porosity increased from 23.0% initially to 26.7% after four cycles and then remained nearly stable, whereas connected porosity increased to 25.4% after ten cycles. These complementary observations indicate that post-thaw surface appearance alone may underestimate freeze–thaw-induced structural disturbance and highlight the importance of moisture condition and early-cycle evolution in cold-region engineering.

To address the challenges of immature theories and technologies for ecological restoration in high-altitude mining areas, this study focuses on the Jiangcang mining area at an altitude of 3850 m, aiming to develop an effective and comprehensive ecological restoration model. Through on-site investigation and diagnosis, a site-specific approach was adopted, incorporating topography restoration following natural terrain, on-site screening of mine waste for cover soil materials, soil improvement with bulk blending fertilizer, mixed sowing of native grass species, slope stability analysis using Bishop’s method, and environmental monitoring. The results showed that the restored area reached 9303 mu. The soil structure and holding capacity of coal gangue and waste soil were effectively improved, and the artificial soil exhibited good fertility. Vegetation coverage exceeded 90%, outperforming that of the surrounding natural grassland. Surface water quality met the Grade II standard, and all slope safety factors exceeded 1.20, indicating that potential geological hazards were significantly eliminated. These findings suggest that this integrated ecological restoration model successfully restored ecosystem functions in the mining area, providing a replicable and scalable “Jiangcang model” for addressing ecological restoration challenges in high-altitude mining regions, with substantial ecological, social, and economic benefits.