Abstract: Biopolymers exhibit extensive application potential in slope ecological protection. In this study, a series of laboratory experiments were conducted to examine the critical properties of xanthan gum (XG) improved sandy soil and its relevance to slope ecological protection. The protective efficacy was confirmed through an XG-plant scouring test. Additionally, microscopic experiments were employed to elucidate the underlying mechanism by which XG augments the ecological protection of slopes. The findings reveal that XG can significantly improve the structural stability of sandy soil, with its effectiveness being closely linked to dosage and curing duration. Under optimal conditions of 1% XG dosage and 28 days of curing, the compressive strength of sandy soil increases from 0 to 1 485.78 kPa, the disintegration rate declines from 100% to 50.99%, the permeability coefficient diminishes by four orders of magnitude, the erosion rate reduces to 1.06 g/min, and the surface hardness reaches 755.09 kPa. XG exerts no detrimental effects on plant growth and, to a certain extent, fosters it. The synergistic interplay between XG and plants enhances the erosion resistance of sandy soil. XG improves the structure of sandy soil via filling and bonding, film coating, and wrapping, forming a dense biological cementation layer on the slope surface. This not only ensures favorable macroscopic properties but also mitigates the impact of rainfall and runoff on the internal slope structure, thereby providing a stable soil-water environment conducive to plant growth and effectively achieving ecological slope protection.

Key words: xanthan gum, sandy slope, engineering characteristics, ecological slope protection, protection mechanism