Abstract: The stability of the south slope of an iron mine is affected by water accumulation in the adja⁃ cent southern pit. To elucidate the slope failure mechanism under the influence of water infiltration from the adjacent mine，a comprehensive methodology integrating engineering geological investigation，hydrogeologi⁃ cal analysis，rock mass mechanical testing，numerical simulation of seepage fields，and limit equilibrium analysis was employed. The stability of both the current and final slopes was systematically evaluated under various combinations of pit water levels and loading conditions. Results indicate that the safety factors of the current slope under all simulated water levels and load combinations meet regulatory requirements. Howev⁃ er，for the final slope，when the pit water level exceeds -22 m，the safety factor along the 1-1 section falls below the safety threshold. The analysis of the seepage field indicates that the rise in the water level of the mine pit will lead to the elevation of the slope infiltration line and the upward movement of the seepage points on the slope surface, significantly deteriorating the mechanical properties of the rock mass.Further FLAC3D numerical simulations show stress concentration at the slope toe，with plastic zones dominated by shear failure，albeit limited in extent，indicating a low probability of overall slope failure. This study ulti⁃ mately identifies -22 m as the critical safety threshold for the water level in the adjacent mine pit. The find⁃ings provide significant guidance for open-pit mine slope design and water hazard prevention in areas with similar hydrogeological conditions.

Key words: water accumulation of mine pit , limit equilibrium method, numerical simulation, stabili? ty analysis