Freeze-thaw cycles (FTC) influence soil erodibility (K-r) by altering soil properties. In seasonally frozen regions, the coupling mechanisms between FTC and water erosion obscure the roles of FTC in determining soil erosion resistance. This study combined FTC simulation with water erosion tests to investigate the erosion response mechanisms and key drivers for loess with varying textures. The FTC significantly changed the mechanical and physicochemical characteristics of five loess types (P < 0.05), especially reducing shear strength, cohesion, and internal friction angle, with sandy loam exhibiting more severe deterioration than silt loam. Physicochemical indices showed weaker sensitivity to FTC versus mechanical properties, with coefficients of variation below 5 %. Wuzhong sandy loess retained the highest K-r post-FTC, exceeding that of the others by 1.04 similar to 2.25 times, highlighting the dominant role of texture (21.37 % contribution). Under different initial soil moisture contents (SMC), K-r increased initially and then stabilized with successive FTC, with a threshold effect of FTC on K-r at approximately 10 FTC. Under FTC, the K-r variation rate showed a concave trend with SMC, turning point at 12 % SMC, indicating that SMC regulates freeze-thaw damage. Critical shear stress exhibited an inverse response to FTC compared to K-r, displaying lower sensitivity. The established K-r prediction model achieved high accuracy (R-2 = 0.87, NSE = 0.86), though further validation is required beyond the design conditions. Future research should integrate laboratory and field experiments to expand model applicability. This study lays a theoretical foundation for research on soil erosion dynamics in freeze-thaw-affected areas.

Pisha sandstone is a kind of sandstone which is easy to collapse by water in Shanxi, Shaanxi and Inner Mongolia of China, and suffers from hydraulic erosion all the year round. In recent years, some scholars have used microbial induced calcium carbonate precipitation (MICP) technology to solidify Pisha sandstone to improve the water erosion resistance of Pisha sandstone. However, for the climate environment with low average temperature in Pisha sandstone area, the commonly used Sporosarcina pasteurii are not well adapted. The purpose of this study is to use the indigenous strainsto solidify the loose Pisha sandstone, and to compare the growth adaptability, mechanical properties and water erosion resistance of the solidified layer with Sarcina pasteurii at different temperatures, and to explore the mechanism of different temperatures and strains affecting the microbial solidification of Pisha sandstone from the micro scale. At the same time, a mixed bacterial liquid solidification test was also set up. The results showed that the solidified thickness of indigenous strains was 4.65 % higher than that of Sporosarcina pasteurii, and the thickness and strength of mixed strains were increased by 19.57 % and 36.62 %, respectively. The growth and solidification effect of indigenous strains were less affected by low temperature. Compared with Sporosarcina pasteurii, at low temperature, the bacterial concentration decrease of indigenous strains was reduced by 26.13 %, the thickness loss of solidified layer was reduced by 13.04 %, and the strength loss of solidified layer was reduced by 13.39 %. The effect of low temperature on the growth of bacteria is mainly reflected in affecting the maximum concentration of bacteria and the growth rate. The effect on MICP mainly reflected in affecting the life activities of bacteria and the crystal form and morphology of calcium carbonate. The research results provide a theoretical basis for the MICP technology application of indigenous strains and multistrains in Pisha sandstone area soil reinforcement and solidification slope.

Loess has high water sensitivity and exhibits poor characteristics such as weak cementation and high porosity. Under heavy rainfall, loess fill slopes are prone to erosion and landslides, posing serious threats to public safety and property. In light of these serious threats, this study employed the method of spraying polyvinyl alcohol (PVA) solution to improve loess fill slopes and systematically examine its protective effects. Through field investigations and combined laboratory and outdoor tests, this study comprehensively evaluated the mechanical properties, anti-aging and anti-erosion performance of loess after PVA solution spraying. Scanning electron microscopy was used to reveal the mechanism of PVA action at the microscopic level. The results showed that after treatment with PVA solutions of varying concentrations, the mechanical properties of loess samples were significantly enhanced, while also exhibiting excellent anti-aging and water resistance performance. Additionally, PVA-treated loess fill slopes exhibited excellent rain erosion resistance. A microscopic structural analysis showed that PVA fills the internal pores of loess, strengthens inter-particle bonding, and uses its hydrophobic groups' water-repellent action to effectively enhance slope stability and erosion resistance. In conclusion, PVA treatment not only significantly enhances the protective effects of loess fill slopes but also holds important value in improving soil sustainability and environmental protection.

This paper investigates the effect of integrating Alfa fibers into compressed earth blocks (CEBs) stabilized with varying Portland cement contents. CEB composites were manufactured with earth stabilized using different cement contents (5% and 10% by weight) and Alfa fibers reinforcement (0-0.4% by weight), compressed at 10 MPa with a compaction loading press. After 28 days of drying, the CEBs underwent diverse experimental tests to evaluate their physical, mechanical, and durability properties. The findings indicated that incorporating fibers led to a diminution in unit weight, ultrasonic pulse velocity, and dry compressive strength. Moreover, an increase in water absorption was linked with higher fiber content and less cement stabilizer. Despite the drop in mechanical strength, CEBs with lower cement (5%) and higher fiber content (0.4%) show better thermal performance. Thermal conductivity values were decreased from 0.5166 W/m.K (10% cement without fibers) to 0.3465 W/m.K (5% fibers with 0.4% fibers). The findings show also satisfactory erosion resistance, which could play a crucial role in areas prone to extreme weather events (floods and storms). According to the findings of this research, this material has potential as a promoting composite for the building materials industry.