Abstract: Due to previous unlicensed mining in many metal mines, many different sized mined-out areas are left underground. And volume of some large mined-out area could reach to 10000 m3 and 10000 m2 square meters are exposed. It is the main reason of causing large-scale rock burst and collapse hazard. To order to guarantee the safe stoping of underneath and the adjacent level, waste rock filling carried out on the reasonable level, then the stress layer formed was proposed. Taken a gold mine as an example, stress and shear strain increment situation of surrounding rock before and after large mined-out area filling were researched by numerical simulation method. Numerical results indicate that surrounding rock stress concentration of large mined-out area decreased obviously. Tensile stress area decreased accordingly and the value was little. Value of shear strain increment decreased and the area of shear strain increment were unconnected after filling treatment, and the potential safety hazard was eliminated.

Key words: Large mined-out area, Waste rock filling, Numerical simulation