# Deformation Analysis of Large-Scale Rock Slopes Considering the Effect of Microseismic Events
## 4 Numerical Simulation of the Rock Slope
### Results Analysis  
Figure 11 demonstrates the displacement nephogram of the rock slope during the excavation of the spandrel arch slope considering the MS event damage effect. Figure 12 shows the displacement vector of the rock slope at excavation to 550 m. The \(\Delta\)Mzjc-3 monitoring point of the multipoint extensometer was chosen as the displacement monitoring point of the numerical simulation. Figure 13 indicates the relationship between the horizontal and total displacement of the displacement monitoring point and the excavation process. (1) The excavation-caused slope deformation was composed of the vertical resilience displacement and horizontal displacement. The slope deformed upwards to the valley. However, the degree of deformation of the slope surface was weakened due to the additional anchoring effect. The maximum deformation of the slope was less than 30 mm. (2) The maximum displacement of each layer after excavation occurred near the excavation face, especially at the foot of the weak structural plane. When the excavation reached the 720 m elevation, the largest displacement appeared in the C3 and C3-1 exposed areas; when it reached the 680 m elevation, the largest displacement appeared in the F17 exposed area; and when it reached the 650 m elevation, the largest displacement appeared in the LS3319 exposed area. (3) The influence of the horizontal unloading effect on the slope increased constantly with the lower excavation plane, thus increasing the proportion of the horizontal displacement in the total. When excavation reached the 720 m elevation in the middle and upper part, the horizontal displacement accounted for approximately 21% of the total displacement; when excavation reached the 550 m elevation in the lower part, the horizontal displacement accounted for approximately 41% of the total displacement.  
Figure 14 shows the shear strain rate of the rock slope considering the MS damage effect during the excavation process of the spandrel arch on the left bank slope. The red area indicates the largest shear strain rate. After the slope excavation began, the stress concentrated near the weak structural plane due to excavation disturbance, resulting in a large shear strain rate. Shear strain occurred and became more obvious at a lower excavation elevation. The unloading depth of the surrounding rock mass also increased. When excavation reached an elevation of 550 m, the shear strain rate increased dramatically in the wedge area formed by F17 and LS3319, indicating that excavation in the lower part of the slope will affect the deformation on the upper structural plane. The large shear deformation occurred in the interlayer disturbance zone LS3319, mainly due to the presence of large ground stress and weak layers on the upper disc wall. The increase in horizontal unloading after excavation expands the horizontal displacement, resulting in tensile shear deformation of the surrounding rock. Moreover, the shallow surrounding rock mass in this area was columnar-jointed basalt with poor resistance to excavation disturbance. Therefore, to avoid dangerous slip blocks formed by slip surface cutting, the columnar jointed basalt at altitudes of 660 m to 628 m should pay attention to the excavation process and support over time.  
Figure 10: Import of MS data to the numerical model during the selected period between 1 April 2016 and 31 December 2016. (**a**) Front view, (**b**) top view, and (**c**) numerical model considering the MS effect.  
Figure 11: Slope displacement nephogram considering the effect of MS event destruction during excavation at an elevation of (**a**) 800 m, (**b**) 720 m, (**c**) 680 m, (**d**) 650 m, and (**e**) 550 m.  
Figure 12: Displacement vector graph of the rock slope with excavation to an elevation of 550 m.  
Figure 13: The variation in the horizontal displacement and total displacement at the monitoring point.