Analysis of the Root Mechanical Reinforcement Effect of Typical Vegetation for Slope Protection in Open‐Pit Mine Waste Dumps

ABSTRACT This study investigated the reinforcement effects of root systems from three typical slope protection plants in a waste dump on soil stability. By measuring the tensile mechanical properties of roots and the shear performance of root‐soil composites, the Wu–Waldron model (WWM) was employed to calculate the shear strength of soil samples. Model parameters were modified to quantify the additional cohesion provided by each plant species' root system at different soil depths. The results indicate that the root area ratio (RAR) of all three herbaceous species decreased with increasing soil depth. The root length density (RLD) of alfalfa ( Medicago sativa ) initially increased and subsequently decreased with greater soil depth, whereas the RLD of both cogongrass ( Imperata cylindrica ) and goosegrass ( Eleusine indica ) consistently decreased with increasing soil depth. The tensile properties of the three herbaceous species exhibited a power‐law relationship with root diameter. Tensile force increased with increasing root diameter, while tensile strength decreased significantly as diameter increased. The root system can modify the mechanical characteristics of the shear behavior of root‐soil composites, enhancing the peak shear strength, extending the displacement at peak shear, and improving the overall shear resistance of the soil. At a water content of 10.5%, both plain soil and root‐permeated soil reached their maximum values of cohesion and internal friction angle, which decreased with further increase in water content. Soil depth and root presence had negligible effects on the internal friction angle. The shear strength of root‐permeated soil was consistently higher than that of plain soil, with the incremental additional cohesion following the order: goosegrass > cogongrass > alfalfa. The correction factor k for the Wu–Waldron model decreased with increasing soil depth. The findings of this study provide a scientific basis for the ecological restoration of slopes in open‐pit mine waste dumps, offering guidance for the selection and arrangement of suitable slope protection plants to enhance the stability of waste dump slopes.