关键词: 露天转地下开采, 露天采坑底部, 地表变形, 隆起, 活化作用

Abstract: Based on GPS monitoring data, the movement and deformation rules of surrounding rock of open pit in the Longshou Mine of Jinchuan Company have been analyzed. The monitoring results show that underground mining has caused rock mass movement and large-range deformation, with two subsiding troughs separated by a central uplifting zone formed on the surface. The maximum settlement of the hanging wall sink area and footwall sink area are 767 mm and 1 078 mm respectively as well as the maximum uplift amount of the rising area in the open pit bottom are 648 mm. And physical simulation experiment has been conducted to simulate the movement and deformation process of surrounding rock mass of open pit from open-pit mining to underground mining. The experimental results are consistent with the monitoring results．And the uplift phenomenon of the bottom of open pit in both open-pit mining and underground mining stages has been clearly observed．Moreover, the uplifting mechanism of the open pit bottom after the transformation from open-pit mining to underground mining has been theoretically analyzed, from which a conclusion has been drawn that the earlier movement and deformation of slope rock mass caused by open-pit mining would be activated again by the underground mining activities. And when the uplifting amount of the open pit bottom caused by the activation is larger than its settlement caused by underground mining, the open pit bottom will rise because of the extrusion.

Key words: transformation from open-pit to underground mining, bottom of the open pit, ground deformation, uplift, activation