Abstract: In the tailings discharge into the mined-out open pit during the transfer period of open casting to underground mining, the mutual effect of the seepage field and stress field can lead to the complication of the analysis of the room roof stability in underground mining. The paper, by means of finite element software simulation technology, analyzes and summarizes the distribution law of the seepage field and stress field of the mined-out open pit under different excavation and tailing discharging conditions, and makes the coupling analysis of the two fields. The coupling analysis result indicates that the roof of the underground room is stable when the maximum discharged tailing height is no more than 40m.

Key words: Mined-out open pit, Tailing discharge, Seepage field, Stress field, Coupling analysis