## 4 Analysis of Vertical Bearing Capacity of Large-Diameter Multi-Disc Soil Anchor
### Axial Force Analysis of Large-Diameter Multi-Disc Soil Anchors  
Firstly, the transverse sections of the large-diameter multi-disc soil anchor and the equal-diameter soil anchor models were carried out on the operation interface of FLAC3D. Thus, six sections were obtained, and the ID number of each section unit was obtained. Then, the corresponding command flow was input in the command window to obtain the stress value of each unit. Finally, the axial force value of each section was calculated according to Equation (1). \[F_{i}=\sigma_{i}s_{i} \tag{1}\]  
where \(\sigma_{i}\) is the average stress of the section; \(s_{i}\) is the area of the section. Figures 9 and 10 show the variation in axial forces of soil anchors with large-diameter and multi-disc soil anchors and the same-diameter soil anchors under different loads. By comparing the axial force diagram of large-diameter multi-disc soil anchors and that of equal-diameter soil anchors, it can be seen that the axial force changes of large-diameter multi-disc soil anchors and equal-diameter soil anchors under different loads have similarities and differences. The similarities are as follows: Under the same load, the axial force of large-diameter multi-disc soil anchors and equal-diameter soil anchors gradually decreases with the increase in buried depth. At the same buried depth, the axial force of large-diameter multi-disc soil anchors and equal-diameter soil anchors gradually increases with the increase in the applied load. The differences are as follows: By observing the axial force change diagrams of the two soil anchor models, it was found that under the same load, the axial force of the soil anchor with the same diameter decreases linearly with the increase in the buried depth of the soil anchor. However, under the same load, the axial force of large-diameter multi-disc soil anchors decreases in a stepped manner with the increase in the buried depth of the soil anchors. This is because the anchor disc shares part of the applied load, and makes the contact area between the soil anchor and the surrounding soil larger. Thus, the applied load can be better transferred to the surrounding soil of the soil anchor and the axial force drops sharply at the position of the anchor disc. The combined action of the soil anchor and surrounding soil is strengthened, the ultimate pulling capacity of soil anchor is increased, and the vertical displacement of the soil anchor is reduced. The anchors of the large-diameter multi-disc soil anchor model are denoted as anchors 1, 2, and 3, successively, from the anchor head downwards. According to the calculated axial force value of the section, and then according to Equation (2), the load borne by each disc of the new large-diameter multi-disc soil anchor can be calculated. \[\delta_{i}=F_{j}-F_{j-1} \tag{2}\]  
where \(F_{j}\) is the axial force of the top section of the \(J\) anchor disc. \(F_{j-1}\) is the axial force of the bottom section of the \(j-1\) anchor disc. The loads borne by each anchor disc of the large-diameter multi-disc soil anchor model under different loads are shown in Figure 11. The loads borne by the three anchors of the large-diameter multi-disc soil anchor model all increase with the increase in the applied loads. When the applied load is less than 112.5 kN, the load borne by anchor disk 1 is greater than that borne by anchor disk 2, and is less than that borne by anchor disk 3, and the load borne by the three anchor disks is almost proportional to the applied load. When the load is greater than 127.5 kN, the load borne by anchor disk 1 is less than that borne by anchor disk 2, and is less than that borne by anchor disk 3, and the load growth rate of anchor disk 1 gradually increases, while the load growth rate of anchor disk 2 and anchor disk 3 gradually decreases.