Abstract: Nihe Iron Mine with burial depth of over 600m is designed to be exploited by two-stage（-750 m lever，-830 m lever）backfill mining method in its first phase project.The stability of opening roadways is one of the key factors that affect the selection of stepwise mining sequence.The typical exploration profiles are chosen to establish two-dimensional finite element calculation models.Two calculation schemes which are the bottom-up stage mining sequence（scheme one）and the top-down stage mining sequence（scheme two）are formulated according to the possible stepwise mining sequences.Finite element stress analysis is conducted at different mining steps of the two schemes.The surrounding rock stress distribution of the opening roadways and safety factors of roadway stability are contrasted in the two schemes to select the reasonable stage mining sequence.The results show that tensile stress occurs in the fractional rock-mass around the majority of opening roadways during exploitation in the two mining sequences.Compared with scheme one,tensile stress distribution region in scheme two is smaller,and minimums of minor principal stress in the surrounding rock of opening roadways are larger,with higher safety factors and more stable opening roadways.Therefore,scheme two which adopts the top-down stage mining sequence,namely mining -750 m level first and -830 m level later,is optimal.

Key words: Stepwise mining sequence, Stress analysis, Stress distribution, Roadway stability, Safety factor