Abstract: Based on the landslide of Open-pit Iron Mine area A in Nanfen,the stability coefficient of the slope body is calculated,and the most dangerous sliding surface and the change of the sliding surface under the action of outside influences are searched out,from the views of theory analytical and quantitative method,by using Geo-Slope software.After through analysis and research on slope stability,it is found that the slope block was basically in a state of limit equilibrium when excavated to 334-328 platform.At this time,it should stop excavating,observed closely the stability condition of the slope body,and prepared for the evacuation of personnel and equipment.It was not excavated until the sliding occurs under the effect of blasting or rainfall.In fact,the 370 platform was slid locally in a heavy rain when the excavation arrived at 340m platform on October 5.It avoided the great casualties and economic losses due to the early withdrawal.

Key words: Open iron ore, Landslide, Geo-Slope, Sliding surface, Stability analysis