Abstract: In order to study the slope stability of the Hunchun Zijin Shuguang gold and copper open pit,the 3GSM structural plane photogrammetry and point load test are carried out.Then it takes the quality grading index for main rock basis,and uses HoekBrown to study mechanics parameters of the slope rock mass.The threedimensional model of the open pit mining is established combining with the medium to longterm mining plan of open pit.An elasticplastic constitutive model is used to calculate the slope stability based on FLAC 3D.The results of threedimensional numerical simulation analysis show that:①The north slope stability is affected by fault structure and fracture zone,the quality of rock mass is class IV,and the local fracture zone is class V;②After excavation to the 6th year,the plastic zone is mainly distributed in the northeastern slope and fault alteration zone of the middle slope;③After excavation to the final boundary slope,the plastic zone in the deep part of the northwest slope is obviously increased in the size of area and the degree of penetration.Reinforcement and drainage measures should be taken for the safety of slope.

Key words: openpit mine, slope stability, FLAC3D, threedimensional numerical simulation