## 3 Characterization of Anchor Cable in FDEM
### Results
#### 4.2.3 Analysis of Entire Dynamic Evolution Process of the Landslide-Anchorage Structure System  
Figure 12 is the schematic diagram of the entire process of landslide dynamic evolution under unreinforced conditions at different seismic intensities. From the figure, it can be seen that the evolution process under different seismic intensities has commonalities and can be roughly divided into the following stages:  
Figure 11: Time histories of anchor cable axial force at the structural plane under different seismic intensities. (**a**) Seismic intensity VII. (**b**) Seismic intensity VIII. (**c**) Seismic intensity IX. (**d**) Seismic intensity X. 1. Initial ground stress equilibrium stage (Figure 12a). This stage takes 1.5 s. The kinetic energy of the model is calculated to be within 50 J, and then the dynamic calculation stage begins. The static boundary conditions are converted into dynamic boundary conditions, and the seismic loads are loaded at the bottom of the main model and the free field at the same time. 2. Sliding surface penetration stage. When the seismic intensity is VII, tensile cracks caused by reciprocating dynamic loads first appear at the toe of the lower part of the inclined sliding surface at \(t=10\) s (7.27 s for VIII, 6.33 s for IX, and 5.45 s for X), followed by shear failures on the horizontal sliding surface, and tensile failures on the lower part of the trailing edge structural plane (Figure 12b); and finally, \(t=10.02\) s (7.5 s for VIII, 6.45 s for IX, and 5.48 s for X), the inclined sliding surface and the trailing edge structural surface keep extending to penetration for shear failures under the dual effects of gravity and seismic load (Figure 12g). At this stage, the crack number of the model at all seismic intensities grows to 98 (Figure 13), and the time required for the sliding surface to penetrate continues to decrease with increasing seismic intensity. As shown in Figure 14, the model kinetic energy changes little in this stage and is caused only by seismic loads. 3. Dynamic failure stage. When the seismic intensity is VII, \(t=11.5\) s, under the dual effects of dynamic load and sliding extrusion, the rock mass at the lower part of the sliding body is gradually fragmented (Figure 12c), and the crack number grows to 246 (Figure 13), and the kinetic energy of the model starts to increase dramatically at this point (Figure 14). After the sliding body slides down for a certain distance as a whole, the block at the upper free face is gradually ruptured, and the block starts to spall and fall (Figure 12d, \(t=15.5\) s), the crack number surges to 830 (Figure 13), the falling blocks collide with the slope surface resulting in the intensification of the degree of fragmentation (Figure 12e, \(t=17.5\) s), and the crack number becomes 1638. The kinetic energy also reaches the maximum value during this stage (Figure 14, 1,537,878 J, \(t=15.97\) s). Other seismic intensities show some different characteristics at this stage: at seismic intensity VIII, the rock mass at the upper of the sliding body is fractured before the sliding body slides down (Figure 12h, \(t=9.5\) s), and the landslide occurs at \(t=11.5\) s (Figure 12i). The maximum crack number and kinetic energy at this stage also become larger with the increase in seismic intensity, which is 1313 (Figure 13, \(t=12.48\) s) and 2,086,209 J (Figure 14, \(t=12.48\) s), respectively; the evolution process at seismic intensities IX and X is the same as that at intensity VIII, in which the maximum crack number and kinetic energy increase with the seismic intensity (IX: 1456, 2,679,335 J, \(t=10.24\) s; X: 1547, 5,725,569 J, \(t=10.23\) s). However, due to the increase in seismic intensity, the bedrock also fractures at intensity IX (Figure 12j), and even partially collapses at intensity X (Figure 12k). 4. Energy dissipation stage.