# Stability and Distribution of Rock Slope under Asymmetric Excavation
## 2 Mining Analysis of Fushun West Open Pit
### Asymmetric Excavation and Fault Impact Analysis  
Based on the fault occurrence studied in reference [23] and the E2000 profile of the West Open Pit shown in Figure 1, a two-dimensional numerical model of the E2000 profile was established, as shown in Figure 2. The model is 4200 m long and 1100 m wide. Since the West Open Pit contains a tectonic area with folds and faults, there is often a large amount of horizontal tectonic stress. Therefore, a certain horizontal tectonic stress was applied in the X direction, the magnitude of which was 1.5 times that in the direction of the self-weight stress [23]. By setting the construction stage, the corresponding grid group was passivated and activated to simulate the excavation and backfill mining of the Fushun West Open Pit. By monitoring the surface subsidence and southward deformation of W200-E3200 on the north side of the Fushun West Open Pit (Figure 3), it was seen that the subsidence and southward deformation at the E300 and E500 profiles were more serious than those at the other profiles. At the same time, the subsidence and southward deformation from profile E1800 to profile E3200 tended to be stable, and the subsidence and southward deformation of profile E2000 changed more seriously in this interval. By September 2023, a backfill mining treatment of E2000 was being carried out in the Fushun West Open-Pit Mine. The E2000 section was in the middle of the whole West Open-Pit Mine, and the geological conditions were representative to a certain extent. To sum up, four representative profiles, E200, E400, E2000, and E3200, were selected. Based on Table 2 and the geological profile, a two-dimensional excavation model was established to obtain the surface horizontal  
Figure 1: E2000 geological profile drawing. Figure 2: Numerical model of the E2000 section. displacement, vertical displacement, and slope stability coefficient on the north side of the above profile. Figure 4 shows the variation curves of the surface horizontal and vertical displacements on the north side of the West Open-Pit Mine with the distances from the top of the slope at the position of the E2000 profile in the numerical simulation in this paper and in the literature [23]. The horizontal displacement of the surface on the north side of the West Open Pit shows a tendency to dump into the pit. Gradually moving away from the top of the slope, the horizontal displacement of the surface of the north slope shows a gradual decreasing trend, and a sudden change occurs at the position of the F1 fault and F1a fault. After that, although there is a stepped change phenomenon at the position of the small fault, the amplitude is not large and the whole slope tends to be stable. In the vertical displacement diagram, it can be seen that the surface uplift changes before the F1 fault, while the surface displacement after the main F1 fault is dominated by subsidence. The displacement changes significantly between the two faults, with a large change rate. After that, the subsidence shows the same change trend as the horizontal displacement. By comparing the dispositions of the merged and unmerged northern faults in the E2000 section, we can see that the two main faults have a blocking effect on the surface displacement of the northern faults. The main reason for this phenomenon is that due to the poor integrity of the reverse fault, the internal stress of the rock and soil body changes under the action of excavation unloading, and deformation disharmony occurs among different structures divided by the fault, resulting in deformation mutation. Figures 5 and 6 show the displacement cloud maps at E200, E400, E2000, and E3200 and the surface displacement line map of the north slope, respectively. With the increase in the position of the F1 and F1a faults from the top of the slope and the change in the dip angle, the transverse and vertical displacement values of the surface of the north slope increase as a whole.