Numerical simulations have gradually developed from two-dimensional to three-dimensional with the development of computer technology. For example, [PERSON] et al. [27] coupled the discrete fracture network with the DEM to provide a solution to evaluating the mechanical behavior of real three-dimensional structures where fracture persistence could not be assumed. A practical case is studied to show the complete method from photogrammetric data acquisition to numerical simulation of the potential progressive failure process of the rockmass. [PERSON] et al. [28] used the discrete element software 3 DEC to capture the basic three-dimensional characteristics of the landslide and form a post-failure structure similar to that observed in the field. [PERSON] et al. [29] used 3 DEC to numerically simulate the excavation of a rock slope of the Puli-Xuanwei Expressway in Yunnan Province. By comparing the rock slopes under different stratum angles, directions, rock characteristics, and thicknesses, they obtained the possible failure modes of the slope and the mutative regulation of safety factors under different conditions. [PERSON] et al. [30] used 3 DEC to analyze the stratum and surface movement and damage caused by open-pit slope mining. In addition, [PERSON] et al. [31] used an FEM/DEM modeling method to study the formation of the basement failure surface in an open-pit slope directly caused by cave mining, and emphasized the importance of rock mass tensile strength and its influence on slope response induced by collapse. [PERSON] et al. [32] proposed the DFN-DEM model combined with photogrammetry technology to evaluate the stability of potentially unstable rock slopes. The model describes the yield and fracture of the intact rock matrix along pre-existing discontinuities. [PERSON] et al. [33] proposed a three-dimensional numerical model based on the discrete element method to predict the deformation and failure of rock slope and avoid the problem of over simplification of the limit equilibrium method. [PERSON] et al. [34] considered the structural anisotropy effect caused by rock joints, blocks and pore water pressure, and studied the static stability of rock slope with an excavation depth of 15 m. [PERSON] et al. [35] used the particle discrete element program to analyze the dynamic failure of rock slope. Four main failure mechanisms are identified, which lead to three different failure modes, corresponding to the well-documented dynamic rock slope failure modes observed in natural slopes. Moreover, [PERSON] et al. [36] used 3 DEC to study the rock collapse behavior of Xiandu Mountain caused by Typhoon Morakot and simulated the wedge failure of the landslide. [PERSON] et al. [37] established a three-dimensional numerical model by using 3 DEC software and combined it with the mechanical properties of the stratum, geological structure, rock-mass, and discontinuity to analyze the stress, deformation, and stability of an excavated slope in China. The method used in this paper will be helpful in determining the true three-dimensional stress, deformation, and stability analysis of the rock slope. [PERSON] et al. [38] performed discrete element numerical simulation using an equivalent discontinuity model to simulate rock movement and failure caused by mining. [PERSON] et al. [39] used the DEM to simulate the failure process of the Xiaogangjian landslide, emphasizing the influence of discrete fracture networks and rainwater infiltration. [PERSON] et al. [40,41] applied the DEM to simulate the deformation behavior of slate slope under the influence of long-term gravity and material metamorphism, used the DEM to simulate the deformation and sliding process of highly active slope elements, and used the model to predict the slope behavior under the condition of wetting geotechnical materials. However, when to properly terminate the discrete element calculation process remains a difficult challenge. Discrete element calculations are an iterative process.