Evolution Analysis of Root Reinforcement Mechanical Effect of Typical Plant Protection on Loess Slope

Plant protection is important for improving the mechanical stability of shallow slopes and rehabilitating the ecological environments of road areas. To investigate the reinforcing effect of herbaceous plants on loess slopes, a typical slope-protecting plant, Festuca arundinacea, was selected as an example. Morphological parameters of root development at each growth stage were obtained, and tensile tests were conducted to assess the evolution of the mechanical properties of the roots. Additionally, the shear strength parameters of the undisturbed root-soil coupling body were obtained by performing direct shear tests. A response surface method was used to analyze the impact of various factors on the mechanical effects of root reinforcement. Furthermore, the growth status of the plants was tracked to interpret the evolution of soil strength, and changes in the mechanical stability of the shallow slope during the root development cycle were analyzed. The results show that the morphological parameters of the roots significantly increase with developmental time, and the interaction between the roots and soil is enhanced. The reinforcing effect of roots on the soil gradually increases and shows a spatial difference, which weakens along the depth of the soil layer. The tensile resistance, ultimate elongation rate, tensile strength, and elastic modulus of the roots exhibit positive correlations with the development time. The upper root system of the soil provides the maximum tensile force, and the effect of the mechanical reinforcement on the coupling body is the strongest. Roots modify the shear mechanical behavior of the soil by increasing the peak shear strength and prolonging the peak shear displacement. When subjected to shear failure, the slope can withstand a greater ultimate shear stress and prolong the failure time, and the reinforcing effect increases significantly with slope inclination. Furthermore, the extent of the influence of normal stress, water content, and root area ratio on the mechanical effects of the soil increases. Based on the roots of Festuca arundinacea, the soil consolidation correction factor k of the WWM model was optimized, and a more precise method for quantifying the soil stabilization effect of roots was established. © 2024 Chang'an University. All rights reserved.