Abstract: Based on the slope system energy principle and FISH language embedded in FLAC3D finite difference method, secondary development of energy calculation in three-dimensional open-pit mine slope excavation model is carried out. Combining energy with catastrophe theory and taking the total dissipative energy of slope system as state variable, the energy dissipation criterion for slope system catastrophe is established. The analysis of sudden change in energy dissipation, plastic zone evolution, safety factor changes and key point displacement is done using the northwest slope of Dagushan open-pit mine as an example. It can be seen that the slope stability evolution obtained by the above analysis is consistent and the applicability of the proposed catastrophe criterion is verified. Results show that energy mutation eigenvalue is a sufficient and necessary mechanical property of slope instability after the ki step excavation. When the excavation is carried out to the 6-8th step, the local rock mass system of the slope is unstable, and the three steps of the 7th, 8thand 9th stage are seriously affected by the excavation disturbance, which is consistent with the actual excavation situation in the field. It provides some theoretical support for preventing the instability of local surrounding rock system during excavation disturbance of open-pit slope.

Key words: slope, energy, excavation, catastrophe theory, instability