Abstract: The hanging wall and footwall of the ⅪV1 main ore body are unstable in Fengzishan lead-zinc deposit. The improved sublevel open stope and caving method was tested. Using three-dimensional finite element, the stability analysis of protective pillar and insulating pillar was presented. The distribution of stress, safety rate and plastic zone was analyzed, and the reasonable stope structural parameters were optimized in the four schemes. The results indicate that the thickness of protective layer has a significant influence on the roof stability, which improves with the increase of stope span during the room stoping. In addition, the roof stability decreases with the increase of stope span. It can effectively ensure the stope stability to select the suitable protective layer thickness and to control the stope span. The results can provide theoretical basis for the mining design and strata control.

Key words: stability analysis, numerical simulation, stope structural parameters, roof protective layer, finite element, insulating pillar