Abstract: With the increasing depth of mining,the study of safe mining depth has become more and more important. At present,the slope stability is mainly analyzed by limit equilibrium method,and the stability state of the structural surface is less studied for precise analysis. In view of the current mining situation in the northeast quarry of Changshanhao Gold Mine,through the investigation of engineering geological conditions and rock integrity,the detailed analysis of the damage characteristics of overturning instability of the slope was done. Based on the data of engineering geological investigation and historical borehole logging data,the complex three-dimensional overall model of the northeast quarry of the mine was established by using 3DMine software,and the stability of the final state model of the slope under the current mining design conditions was analyzed. Based on discontinuous deformation analysis (DDA) method,five profiles of the north gang of the quarry were established,and the stability of the slope under the current mining condition and different excavation depths was analyzed. The results show that the complex geological structure of the northeast quarry,the development of joints and fissures,and the extreme fragmentation of the rock body are the key factors for the deformation and damage of the north slope. The current mining design plan will cause the slope destabilization and damage during the excavation and construction process. The analysis of the DDA model verifies the actual speculative damage and simulates the stability under different excavation depth conditions,and the critical depth occurs when the bottom of the pit is 84 m away from the final design boundary,which provides relevant reference for the design of open-pit mining.

Key words: slope engineering,3DMine modeling,stability analysis,safe mining depth,discontinuous deformation analysis