# Deformation Analysis of Large-Scale Rock Slopes Considering the Effect of Microseismic Events
## 4 Numerical Simulation of the Rock Slope
### MS Parameter Embedding  
The MS monitoring system produced by the Engineering Seismology Group, Canada was adopted in the project. The system was installed completely on 10 November 2014 [27, 30]. The multipoint extensometers were successfully installed and commissioned on 14 December 2014. The slope was excavated near the 680 m elevation. Therefore, there is a lack of comparison between MS data above  
Figure 8: Reinforcement diagram in the numerical model.  
Figure 7: Dam foundation anchor support layout **(a)** elevations from 620 m to 600 m, and **(b)** profile of the arch dam downstream sideline.  
680 m and field data, which has a certain impact on the simulation results. To build the quantitative relationship between rock mass damage and MS activities of the rock slope, the spandrel arch area of the slope was chosen as the research object to analyze the MS events during the selected period. MS events in two periods were selected. The first period was from 1 December 2014 to 31 January 2015 (excavation elevation ranging from 740 m to 680 m). The second period was from April 2016 to 31 December 2016 (excavation elevation ranging from 630 m to 550 m). MS data in corresponding regions were selected. Taking the period between 1 December 2014 and 31 January 2015 as an example, the selected region of MS data was a rectangular region encircled by four locating points with the geodetic coordinates ((E: 589012, N: 3012917), (E: 588989, N: 3012878), (E: 589130, N: 3012797), and (E: 589153, N: 3012836)) in the top view. The spatial scope is a cube at elevations from 740 m to 680 m. A reference point on the dam crest based on a numerical model with geodetic coordinates (E: 589053, N: 3012865, U: 834) and coordinates in the model (172.7, 60, 405) was selected. Based on the preceding coordinates, the coordinate transformation relationship was established to input the MS data in the selected area to the numerical model. During the excavation period, there were a total of 309 MS events. The damage constitutive model considering the rock fracture scale was adopted in all rock elements of the model. It was assumed that the MS monitoring system adopted an annular fault plane. The source fracture zone was equivalent to a disk with a radius of \(r\), which referred to the source fracture scale according to [PERSON]'s model calculation [31]. The formula is as follows:  
\[r_{0}=\frac{K_{c}V_{s}}{2\pi f_{0c}} \tag{6}\]  
where \(K_{c}\) refers to the angular frequency of the P-wave or S-wave; \(K_{s}\) = 2.34 for instantaneous stress relief; \(K_{p}\) = 2.01 and \(K_{s}\) = 1.32 for a quasi-dynamic rounded source [32].  
The MS data were read into the corresponding rock unit in the model, and the source radius was entered. The numerical calculation can obtain the fracture density and fracture damage variable of the corresponding rock unit and the strain increment in the rock unit under the fracture damage. The stress and strain values of this element in the damage status could be obtained from the FLAC3D calculation and circulation. After all the MS data during the selected period were input into the numerical model, the stress and strain field in the damage status of the rock slope could be obtained. Figures 9 and 10 show the spatial distribution of MS events and the relationship between MS information and the model excavation process.  
Figure 9: Import of microseismic (MS) data to the numerical model during the selected period between 1 December 2014 and 31 January 2015. (**a**) Front view, (**b**) top view, and (**c**) numerical model considering the MS effect.