## 6 Conclusions  
By establishing a three-dimensional finite element model, the whole process of staged excavation and support of a complex foundation pit group consisting of six foundation pits was simulated. This paper analyzed the deformation characteristics of the diaphragm wall and the variation characteristics of the axial force of internal support in each foundation pit during the staged construction of the foundation pit group. In particular, the coupling effects on the deformation of the diaphragm walls and the axial force of support were studied emphatically. Moreover, with the change in construction sequences, the variation characteristics of deformation of wall deflection and axial force of internal support were analyzed, and the differences in the coupling effects were compared. The following conclusions can be drawn:  
1. In the original construction scenario (Scenario 1), the lateral deformation of the diaphragm walls at A-2 and C-4 showed the obvious coupling effect from the surrounding excavation, and the maximum change rates were 28.2% and 20.8%, respectively. The coupling effect on the lateral deformation of the diaphragm wall at A-1 and C-3 was not apparent, and the maximum change rates were 3.3% and 4%, respectively. Figure 9: Maximum axial force variation of internal support with different construction sequences. However, the lateral deformation of the diaphragm wall at B-5 or B-6 was hardly affected by the excavation of other pits. 2. In Scenario 1, the maximum axial force in Pit A was far greater than that in other pits, and it increased by 89.6% after the construction of Stage 2, indicating a strong coupling effect. In contrast, the construction of Stage 3 had little impact on the maximum axial force in Pit A and a certain degree of coupling effect on the maximum axial force in Pit C.
3. After changing the construction sequence, the coupling effects on the lateral deformation of the diaphragm walls at A-1, A-2, C-4, and E-10 were obviously different. Among the six construction scenarios, the maximum change rates of maximum lateral deformation at the above positions were 15.9%, 7.5%, 15.4%, and 10.7%, respectively. However, the maximum change rates of maximum lateral deformation at other positions did not exceed 3%. The maximum change rates of the maximum axial force in Pit A and Pit F were 89.5% and 193.6%, respectively, and that in other pits was little affected by the construction sequence. 4. The coupling effect of foundation pit group excavation on the lateral displacement of the diaphragm wall near the existing building was more significant, and the deformation development should be focused on. The constraint of the concrete cushion can effectively reduce the lateral displacement of the diaphragm wall. In addition, the maximum axial force of the support in the pit adjacent to the existing building was obviously affected by the coupling effect of the adjacent excavations. 5. Due to the quantity and the irregular shape of the foundation pits in the foundation pit group, many different construction scenarios can be formulated. However, considering the impact of construction on traffic flow and the safety of the foundation pit group, the six scenarios studied in this paper are representative and reflect the coupling effects between each foundation pit during the construction of the foundation pit group, which can be used as a reference. The practical construction scheme must also be formulated by considering the on-site environment and various other factors. Conceptualization, Y.X. ; methodology, Y.X., Q.Z. and Q.Y. ; software, Q.Y. ; formal analysis, X.Y. and Q.Z. ; investigation, Q.Z. and Q.Y. ; resources, X.Y. and Q.Z. ; data curation, X.Y., Q.Z. and Q.Y. ; writing--original draft preparation, X.Y. and Q.Z. ; writing--review and editing, Y.X. and Q.Y. ; supervision, L.T. ; project administration, X.Y. and L.T. ; funding acquisition, L.T. All authors have read and agreed to the published version of the manuscript.