Study on the strength and erosion resistance of soil-amended substrates for rock slopes in Fugu County.

The Fugu area of Yulin City, Shaanxi Province, China, is a typical Pisha sandstone region that has long faced severe soil erosion issues. While traditional engineering measures provide temporary relief, they struggle to achieve long-term ecological restoration. To address this, this study incorporated xanthan gum and superabsorbent polymer into loess soil at specific ratios for slope soil amendment. Strength and erosion resistance were evaluated through direct shear and 70 mm/h rainfall erosion tests, with reinforcement mechanisms examined via scanning electron microscopy. Results indicate that at a 0.3% XG and 0.15% SAP mixture ratio, the shear strength of samples reached a maximum of 162.75 kPa, representing an increase of approximately 35.6%, while cohesion increased by about 71.7%. Furthermore, under the combination of 0.6% XG and 0.3% SAP, slope soil loss mass decreased by 42.1%, while rainfall infiltration decreased by 32.8%. Combined with SEM results, the incorporation of XG and SAP enhances intergranular bonding by filling soil pore spaces, thereby strengthening particle cohesion and reducing slope erosion. It also increases soil cohesion and improves macroscopic shear performance. In summary, these findings provide valuable references for ecological protection of Pisha sandstone slopes.