Abstract: Aiming at the problem of instability and collapse caused by historical goaf in the north slope of an open-pit quarry，the stability study is carried out by combining numerical simulation with limit equilibrium method. Firstly，Midas software is used to simulate the current slope on the north side. It is found that the safety factor under the condition of self-weight + groundwater is only 1.082，which is lower than the specification requirements，and the maximum equivalent plastic strain is concentrated around the goaf，which has the risk of local instability. Based on this，a comprehensive treatment scheme of drainage and drainage，slope cutting and load reduction and goaf filling is proposed. After the treatment，the simpli‐ fied Bishop method based on the limit equilibrium principle is used to evaluate the stability of the north slope and the east and south slopes after the completion of the infrastructure under three working condi‐ tions of self-weight + groundwater，superimposed blasting vibration and superimposed seismic force. The results show that the safety factor of the north slope is increased to 1.532 ( self-weight + groundwater ) after treatment. The safety factor ranges of the east and south slopes under various working conditions are 1.230~1.641 and 1.323~2.038，respectively，which all meet the safety standard of Grade II slope. The safety fac‐ tors of the three-sided slope under blasting conditions are close to the lower limit of the specification，indi‐ cating that blasting disturbance is the most sensitive factor affecting slope stability. The research results provide a basis for the sustainable and safe production of mines. It is suggested that pre-splitting blasting， hole-by-hole millisecond blasting and strict control of blasting safety distance should be adopted in subse‐ quent mining to reduce dynamic disturbance.

Key words: open-pit mine, slope stability, goaf management, safety factor, blasting disturbance