Research on ecological restoration technology of high-steep slopes of abandoned mines based on geological safety evaluation

The new round of national strategic mineral prospecting requires to pay attention to ecological protection. The ecological restoration of abandoned open-pits is an important step in the comprehensive use of mine land and ecological environmental protection, among which the restoration of high-steep slopes is the focus and difficulty. To this end, an ecological restoration technology pilot study was carried out at the abandoned open pit mine in Dongyuan Village, Lingdong Township, Lanxi City, Zhejiang Province. Through field surveys, engineering geological mapping and engineering drilling, a numerical analysis of slope safety based on the finite element method was conducted for the ecological restoration of high-steep slopes. The analysis results show that the safety factor of the slope reduced from 1.458 to 0.851 with the rainfall, which makes it a safety hazard. Ecological restoration of high-steep slopes shall be complemented by engineering measures, including slope cutting to reduce the slope gradient and the construction of retaining walls at the leading edge of the slope, to meet safety requirements; Adequate drainage can greatly reduce the impact of water on slope safety and improve slope stability. With the ecological restoration design, the safety factor of the slope under heavy rainfall conditions significantly increased and almost maintained at around 1.7, which meets the safety design requirements. This technology demonstration can provide a reference for the ecological restoration of other abandoned mines.