Abstract: To effectively address the issues of severe freeze-thaw erosion and ecological restoration of excavated slopes in alpine regions, our study focused on the excavation slopes in the Duoxiongla Industrial Plaza as a case study. In view of the climatic characteristics and based upon traditional solidified sand with modified materials, we investigated the effects of adding different proportions of straw fiber on the permeability, shear strength, and freeze-thaw resistance of straw fiber reinforced solidified soil. Our analysis aims to examine the effectiveness of reinforcement and solidification, explore optimal ratios, and reveal the underlying reinforcement mechanism. Results demonstrate that the addition of modified material and straw fiber reduced soil permeability and increased soil cohesion when compared to pure sand. Moreover, the internal friction angle remains essentially unchanged. Moisture content is the primary factor that affects soil permeability, while straw fiber is the main contributor to soil cohesion. In addition, the freeze-thaw resistance of reinforced soil is significantly better than that of pure soil. The highest level of freeze-thaw resistance can be achieved when modified material, water, and straw fiber account for 0.234%, 15%, and 0.3% of sand mass, respectively.

Key words: sand, straw fiber, permeability, shear strength, freeze-thaw cycle