关键词: 铁古坑采区, 最终边帮稳定性, 局部强度折减法, 安全系数

Abstract: Tiegukeng mining area of Wuyang Iron Mine is transiting from open pit to underground mining.The underground mining in different stages will have a different influence on the final slope stability of open pit.It will threaten the production safety of underground mining if the unstable working condition of the final slope can not be judged.Two-dimensional finite element numerical model is built by selecting the typical exploratory line profiles.Six working stages was finished with the order of the open pit，-160 m stage，-220 m stage，-280 m stage，-340 m stage and -400 m stage.The safety factors of the hanging wall and the footwall of the final slope are calculated with the local strength reduction method of finite element to analyze the impact of underground mining on stability of the final slope.The results show that：the local strength reduction method with finite element can be used to calculate the safety factors of the hanging wall and the footwall through the numerical simulation.With the underground mining depth increase，both safety factors above decreases gradually.The slope will be kept in ultimately stable condition at the -220 m stage and the hanging wall collapses at the -280 m stage or below.Underground mining has a little impact on the safety factor of the final slope footwall，so the footwall is always kept in stable.

Key words: Tiegukeng mining area, Final slope stability, Local strength reduction method, Safety factor