Abstract: In view of some problems in exploitation of ore-body with multiple mined-out areas,such as hard recycling,weak security in mining,and high rock mixing,Xishimen iron mine is adopted as engineering basis to study the exploitation of ore-body with multiple mined-out areas.Based on analysis of inadaptability of original mining methods and flat bottom structure,and considering the stability of roof surrounding rocks and the features of skarns at footwall,a new scheme that combines inclined drift with flat bottom trench structure and treats skarns as low grade ore is proposed.Several different bottom structures layout,such as double trenchs,and single trench,etc,are formed for different dip angle and thickness,which are suitable for recovery of different orebodies.In the end,the characteristics of the flat bottom trench structure is analysed,and an appropriate supporting measure is proposed for ensuring the scheme going on smoothly.

Key words: Orebody with multiple mined-out areas, Flat bottom structure, Trench,Inclined drift