## 4 Simulation Results and Discussion  
### Lateral Displacements of the Surrounding Rocks  
(1) At an excavation depth of 8 m  
The lateral displacements of the surrounding rocks when the excavation of the foundation pit reached 8 m beneath the ground are illustrated in Figure 6. According to Figure 6, when the excavation depth was 8 m, the maximum lateral displacements of the surrounding rocks were basically similar under different in-time transverse supporting conditions. Before the excavation of the foundation pit, vertical supports of the drilled grouting piles were set. And when excavation of the foundation pit began, transverse supports of concrete bracings were set at a depth of 0.5 m. Then, with continuous excavation of the foundation pit, steel bracings or prestressed anchorages were set when the excavation depth was 0.5 m deeper than the preset depths of the supporting elements, meaning that when the excavation depth was 8 m, the support conditions of the foundation pit were the same for supporting schemes B, C, and D but not scheme A. Therefore, the deformations of the surrounding rocks of the foundation pit under supporting Schemes B, C, and D were the same, while they were relatively smaller when Scheme A was adopted. The similarity of these lateral deformations indicated that lateral deformations of the surrounding rocks could be fully restrained by setting the drilled grouting piles and concrete bracings to a depth of 0.5 m and that it might be unnecessary to set steel bracings at a depth of 4 m (Scheme A). Meanwhile, when the excavation depth was 8 m, the maximum lateral displacement of the surrounding rocks was 0.17 mm, which is far lower than the allowed value of 24 mm required in GB50007-2011 [10]. Figure 6: Lateral displacements of the surrounding rocks at an excavation depth of 8 m.  
At an excavation depth of 16 m  
The lateral displacements of the surrounding rocks when the excavation of the foundation pit reached 16 m beneath the ground are illustrated in Figure 7. When the excavation depth was 16 m, the displacement changes in the surrounding rocks under supporting schemes A, B, and C were basically identical, presenting a P-shape in the excavation direction, while displacements of the surrounding rocks under supporting scheme D were restrained. Meanwhile, the places where maximum lateral displacements occurred were basically located at 7 m underground under the supporting conditions of scheme A, B, and C. Furthermore, the maximum lateral displacement of the surrounding rocks was 2.3 mm when the excavation depth was 16 m, which is far less than the allowed value of 48 mm required in GB50007-2011 [10]. As shown in Table 2, at an excavation depth of 2 m to 8 m, mainly strongly weathered limestone and medium-weathered limestone were found, indicating that surrounding rocks at an excavation depth of 2 m to 8 m might be fissured. Therefore, the deformation controlling the performance of these steel bracings located at 4 m, 8 m, and 9 m was not as intense as that of the prestressed anchorages. However, steel bracings located at 4 m, 8 m, and 9 m somehow served to control the lateral deformations of the fissured surrounding rocks. The lateral deformations of the foundation pit with prestressed anchorages set to 8 m were significantly restrained, and they were lower when steel bracings were set at 4 m, 8 m, and 12 m (Scheme A).