## 5 Influence of Construction Sequence  
### Influence on Lateral Wall Deflection  
In the different excavation sequences of the foundation pit group, the surrounding soil mass will have different unloading processes, which will exhibit different coupling effects. For a single foundation pit, the excavation area, the excavation depth, and the setting of internal support will have a significant impact on the deformation of the foundation pit. The layered and blocked excavation must be followed, and the internal support must be installed in time without over-excavation. For a complex foundation pit group, these essential instructions are also applicable. The foundation pit group of this project includes six pits, and the construction sequence is an important factor affecting the deformation of the foundation pit. In order to better understand the coupling effect of different construction sequences on the deformation of the foundation pit group, the original construction sequence is changed for simulation to analyze the difference characteristics of the support structure. To facilitate the description of different construction stages, the above names of each foundation pit must remain unchanged and the construction content of each stage must be changed, as shown in Table 6. Figure 7 shows the deformation contour image of the diaphragm wall after excavation in each stage. Figure 8 shows the lateral deflection curves of the diaphragm wall after the excavation of the foundation pit group under different construction sequences. It can be seen from Figure 8a that the construction sequence has various influence on the displacement at A-1. In Scenario 5, the lateral displacement value at A-1 is the minimum, at 45.3 mm, while in Scenario 3, the lateral displacement value at A-1 is the maximum, at 52.5 mm, with a difference of 15.9%. The maximum lateral displacement under other scenarios is between the above two. At the same time, Figure 8a shows that the deflection curves of Scenario 1 and Scenario 2, Scenario 4 and Scenario 6 are similar. It can be seen that when Pit A is excavated in the second stage, the specific excavation plans of the first and third stages will have a decisive impact on the lateral deformation of the diaphragm wall at A-1. From Figure 8b, the maximum lateral displacement of the diaphragm wall at A-2 is about 86 mm in Scenario 1 and Scenario 2. In Scenario 4 and Scenario 6, the maximum lateral displacement of the diaphragm wall at A-2 is the smallest, at about 80 mm. The difference between the two reaches 7.5%; that is, when Pit A is first excavated, the deformation at A-2 is maximum, and when Pit A is last excavated, the deformation at A-2 is minimum. In addition, the construction sequence has a greater impact on deformation at A-1, compared with A-2. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Scenario No.**} & \multicolumn{3}{c}{**Construction Sequence**} \\ \cline{2-4}  & **Stage 1** & **Stage 2** & **Stage 3** \\ \hline Scenario 1 (original) & Pit A & Pit B, Pit C & Pit D, Pit E, Pit F \\ Scenario 2 & Pit A & Pit D, Pit E, Pit F & Pit B, Pit C \\ Scenario 3 & Pit B, Pit C & Pit A & Pit D, Pit E, Pit F \\ Scenario 4 & Pit B, Pit C & Pit D, Pit E, Pit F & Pit A \\ Scenario 5 & Pit D, Pit E, Pit F & Pit A & Pit B, Pit C \\ Scenario 6 & Pit D, Pit E, Pit F & Pit B, Pit C & Pit A \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Different construction sequence. It can be seen from Figure 8c,d that the maximum lateral displacement of the diaphragm wall at C-3 is about 103 mm in Scenarios 1, 3, and 4, and the maximum lateral displacement is about 100 mm in Scenarios 2, 5, and 6, with a difference of 3%. In Scenarios 1, 3, and 4, the maximum lateral displacement of the diaphragm wall at C-4 is about 26 mm, and the maximum lateral displacement is about 30 mm in Scenarios 2, 5, and 6, with a difference of 15.4%. Thus, the maximum lateral displacement at C-3 and C-4 cannot reach the minimum value at the same time in the six scenarios; that is, there is no optimal scenario.