## 4 Simulation Results and Discussion
### Settlement of the Surrounding Ground  
(1) At an excavation depth of 8 m  
The settlement values of the surrounding ground at different excavation depths are shown in Figure 8. It can be obtained from Figure 9 that soil heave of the surrounding ground appeared when the excavation depth was 8 m, and the maximum heave value was 0.12 mm. Excavation unloading will lead to heave or settlement of the surrounding ground. If the settlement is lower than the heave, then the surrounding ground will present heave characteristics. According to the lateral deformations of the surrounding rocks illustrated in Figure 5, when the exaction depth was 8 m, the maximum lateral deformation was less than 0.2 mm, indicating that the influences of excavation unload on the settlement of the surrounding ground might be less severe than those on heave. Therefore, when the excavation depth was 8 m, heave took place in the surrounding ground.  
Figure 8: Lateral displacements of the surrounding rocks at excavation depths of 24 m and 31 m.  
At an excavation depth greater than 8 m  
When the excavation depth was greater than 8 m, the settlement changes of the surrounding ground were basically identical when different transverse supporting schemes were adopted. The settlement of the surrounding ground at different distances from the foundation pit presented a funnel shape, and the influential areas of the foundation pit excavation were within 1 to 1.25 times the excavation depth.  
Meanwhile, the influential areas of the surrounding ground during the foundation pit excavation process increased with an increasing excavation depth. When the excavation depth was 16 mm, the settlement of the surrounding ground under transverse supporting schemes A, B, C, and D occurred within 20 m, 22 m, 22 m, and 10 m away, respectively, from the foundation pit. Meanwhile, soil heave also took place when the excavation depth was 16 m when supporting scheme D was adopted, and this might have been caused by prestresses of the prestressed anchorages. Upon further increasing the excavation depth to 24 m and 31 m, the influences of excavation unloading on the settlement of the surrounding ground were more severe than those of heave, and no heave took place around the foundation pit. Meanwhile, influential areas of the surrounding ground were basically identical and within 25 m from the foundation pit under the four transverse supporting schemes, which was because when the excavation depth was 24 m, all the transverse  
Figure 9: Settlement of the surrounding ground.  
support elements had been set, and the settlement of the surrounding ground was therefore restrained due to the deformation-restraining effects of the transverse support elements.  
Furthermore, it can be obtained from Figure 8(b)-d that in terms of controlling the settlement of the surrounding ground during the foundation pit excavation process, transverse supporting scheme D was the most effective, followed by scheme A and scheme B, and scheme C was the least effective. Meanwhile, when the excavation depths of the foundation pit were 16 m, 24 m, and 31 m, the settlement of the surrounding ground under transverse supporting scheme C was the highest among all the other transverse supporting schemes, which were 2 mm, 6.6 mm, and 8 mm, and all these maximum settlement values were significantly lower than those reported in [26], with the maximum numerically calculated settlement being 20 mm with an excavation depth of 18 m, and in [27], with the maximum numerically calculated settlement being about 24 mm.