Study on the impact of pillar recovery on surface subsidence in Sanguikou Lead-Zinc Mine

Focusing on the engineering geological conditions, the shape and distribution of the pillars, as well as the results of the evaluation of the overall stability of the goaf at the Sanguikou Lead-Zinc Mine in Urad Rear Banner Zijin Mining, some of the pillar resources remaining in stope are in a position to be recovered. To clarify the impact of the pillar recovery on the surface deformation at 630 m level and above, it predicts the surface subsidence law and strata movement range, and evaluate the possible impact of related mining activities. This paper is based on the probability integral method of random medium theory to analyze the theoretical calculation of the surface movement and subsidence of the pillar recovery, using the three-dimensional goaf scanning method to establish a refined model of goaf and pillars, and using the FLAC^3D numerical simulation systematically to research the impact of the pillar recovery on the surface subsidence. The results show that the maximum surface subsidence and horizontal movement values in the theoretical calculation and numerical simulation results are the same for the pillar recovery scheme with a safety class I. The influence range of the surface and the subsidence distribution law determined by both are also basically the same, which are mainly concentrated in the dense area of the pillars and the goaf. At the same time, the maximum inclination of the surface is much less than 1 mm/m, the maximum curvature is much less than 0.05 mm/m², and the maximum horizontal deformation is far less than 1 mm/m, which indicates that the surface deformation and subsidence are within a safe range after the pillar recovery, and the surface collapse and other disasters do not occur due to the pillar recovery. The results of the research provide theoretical support for the subsequent mining of the mine.