Study on the preparation of ecological substrates from iron tailing sand and the efficacy for vegetation-based slope reinforcement in cold-arid open-pit mines

The risks of slope instability and ecological degradation are faced in open-pit mine slopes in cold-arid regions due to the combined effects of monsoon climate and frequent mining activities. Ecological restoration can prevent soil erosion and improve the environment, so it is necessary to study the performance of vegetation-growing substrate and the root reinforcement effects in open-pit slope restoration areas. Based on the climatic characteristics and suitable plant species in cold-arid regions, this study The performance indicators of an iron tailing sand (TS)-based ecological substrate, including germination rate, strength, and frost resistance, were systematically evaluated through orthogonal experiments and range analysis in this study. Furthermore laboratory tests were conducted on various vegetation-substrate composites to analyse their mechanical property indicators and root distribution characteristics. The results showed that the optimal mix ratio for the ecological substrate suitable for western Liaoning region is: TS 30%, straw 3%, cement 15%, polyacrylamide (PAM) 0.4%, silica fume 8%. The optimal vegetation combination was tall fescue, lonicera japonica, and pedicularis. The shear strength of the ecological substrate was positively correlated with the root distribution density of tall fescue. An anchoring mechanical model for shallow-rooted plants was established, and a theoretical equation for the taproot anchoring force in vertical-rooted plants was proposed. These results provide a theoretical basis and technical approach for the synergistic regulation of substrate-vegetation-mechanics in mine slope ecological restoration, which is of significant practical importance for promoting green mine construction.