## 3 Characterization of Anchor Cable in FDEM
### Results
#### 4.2.2 Analysis of Dynamic Evolution of the Anchor Cable Axial Force  
Figure 10 shows the distribution of anchor cable axial force at \(t=7\) s under different seismic intensities. As the seismic intensity increases, the anchor cable axial force increases gradually. The strong dynamic load will intensify the magnitude of the slope movement, and the anchor cable can improve the integrity of the rock mass and connect the slope tightly, so it needs a larger axial force to resist the stripping effect of the seismic wave. A high value  
Figure 9: The acceleration time history of monitoring point P9 of the unreinforced and cable-reinforced slopes at seismic intensity VIII. (437.12 kN, 437.05 kN, 436.07 kN and 409.764 kN) is observed in the anchor cable N0 near the slope surface at all seismic intensities, which is caused by the uncoordinated movement of the slope, and it can be inferred that fracture has occurred here by combining with the elevation amplification effect described above. Based on the distribution characteristics of the anchor cable axial force, the fracture of the slope body can be preliminarily judged. The structural plane is the weakest part of the slope, and the anchor cable axial force here increases the fastest with the variation of seismic intensity, which is higher than the other parts of the anchor cable at seismic intensity IX. This is more obvious at seismic intensity X because the structural plane fails, and the penetration plane and the sliding body are formed, so the anchor cable needs to increase its axial force to resist the dual effects of dynamic load and gravity. When the structural plane does not fail, taking seismic intensity VIII as an example, the axial forces of anchor cables N0-N5 at the structural plane are 5.249 kN, 4.618 kN, 4.57 kN, 3.384 kN, 2.857 kN, and 2.099 kN and show a decreasing trend because the distribution of PGA amplification factor within the slope follows the elevation amplification and horizontal surface effects, and the PGA amplification factor is correlated with the anchor cable axial force. When the structural surface fails, taking the seismic intensity IX as an example, the axial forces of the anchor cables N0-N5 at the structural plane are 75.008 kN, 66.945 kN, 73.612 kN, 78.632 kN, 93.878 kN, and 127.694 kN. The anchor cables N0-N2 of the second step have no apparent law, and the effect of seismic waves plays a dominant role here. The anchor cables N3-N5 of the first step show an increasing trend and are larger than the anchor cables of the second step because here they are greatly affected by gravity, and the larger the volume of the sliding body, the greater the effect of gravity. Figure 11 is the time history of the anchor cable axial force at the structural plane under different seismic intensities. It can be seen from the figure that with the increase in seismic intensity, the axial force of each anchor cable grows larger to a different degree  
Figure 10: The diagrams of anchor cable axial force at \(t\) = 7 s for all seismic intensities. (**a**) Seismic intensity VII. (**b**) Seismic intensity VIII. (**c**) Seismic intensity IX. (**d**) Seismic intensity X. (the average maximum axial force of anchor cables under each seismic intensity: VII is 161.165 kN, VIII is 364.878 kN, IX is 563.883 kN, and X \(\geq\) 648 kN). The growth rate is related to the cable location and the seismic waveform (take VII for example, the mutation of the axial force in Figure 11a corresponds to the local peak of the seismic wave), the lowest anchor cable N5 grows the fastest, while cables N4-N0 slow down roughly in order. At the end of the earthquake, the maximum anchor cable axial force does not seem to conform to the law of decreasing from bottom to top, which is related to the seismic waveform and the physical and mechanical properties of the slope; the generation order of crack and the distribution of the stress wave will affect the stress state of the anchor cable, and eventually present an irregular maximum axial force.