## 4 Results and Discussion
### Lateral Wall Deflection
As the excavation and unloading takes place in Pit B, the soil outside moves toward the pit, driving the soil at A-2 to move toward Pit A. The position of A-2 is close to the existing building, making the soil at A-2 more susceptible to disturbance. Thus, the earth pressure on the diaphragm wall at A-2 increases, making the lateral displacement  
Figure 5: Lateral deflection curve of diaphragm wall. increase rate of A-2 larger. A-1 is located between foundation Pit B and Pit C, and the excavation of Pit C makes the soil outside tend to move toward Pit C, causing the soil at A-1 to unload to some extent. Therefore, the increase rate of lateral displacement at A-1 is smaller. From Stage 2-2 to Stage 3-2, the maximum lateral displacement at A-1 decreases from 52.77 mm to 51.01 mm, decreasing by about 3.3%. The maximum lateral displacement at A-2 increases from 84.22 mm to 85.11 mm, increasing by about 1%. Since Pit D is far from Pit A, the excavation in Pit D has little impact on lateral displacement at A-1 and A-2. By comparing Figures 5c,d, it can be found that the maximum lateral displacement at C-3 is much greater than that at C-4. C-3 is close to the pit-in-pit in Pit C. The depth of the pit-in-pit is 29 m, while the excavation depth of Pit C is 22 m. In addition, the constraint of the concrete cushion at C-4 further reduces the lateral displacement at C-4. It can be concluded that the excavation depth and the constraint of the concrete cushion have a great influence on the lateral displacement of the diaphragm wall. According to the Chinese technical standard for monitoring of building excavation engineering (GB50497-2019), the control value of the lateral deformation of the foundation pit classified into grade I is 0.4-0.5% of the excavation depth. Therefore, the control value of the lateral deformation is within the range of 116-145 mm, and the deformation at C-3 is acceptable. It can be seen from Figure 5c-f that, from Stage 2-2 to Stage 3-2, the maximum lateral displacement at C-3 increases from 98.9 mm to 102.9 mm, with an increase of about 4%, and the maximum lateral displacement above the excavation surface at C-4 decreases from 20.2 mm to 16 mm, with a decrease of about 20.8%. The excavation of Pit D drives the soil mass at C-3 to move toward the pit, resulting in the increase in earth pressure at C-3 and the increase in the lateral displacement of the wall. However, C-4 is close to the shared diaphragm wall of Pit C and D, and both sides of the shared diaphragm wall are braced with diagonal supports. Thus, the lateral displacement at C-4 is affected by the great stiffness of the diagonal supports, showing the trend of moving away from Pit C. The process of Stage 3 has little effect on the lateral displacement at B-5 and B-6. Although B-5 is close to Pit E, the shared diaphragm wall of Pit E and Pit B limits the displacement of the wall near B-5. Moreover, the excavation area of Pit E is small, so the impact of excavation can be ignored. In summary, the coupling effect on the lateral deformation of the diaphragm wall at A-2 and C-4 is obvious and cannot be ignored; the adjacent pit excavation will have a greater impact on the deformation of the wall at A-2 and C-4. Thus, during Stage 2 and Stage 3, the influence of the coupling effect on the deformation of the diaphragm wall at A-2 and C-4 can be controlled by adjusting the axial force of the servo steel supports. The duration of excavation must be reduced as far as possible. The additional deformation from the coupling effect must be of concern. The coupling effect on the deformation of the wall at A-1 and C-3 is small, and B-5 and B-6 are hardly affected by the excavation of the adjacent pit. The lateral deformation of the wall at C-3 is the largest. The lateral deformation of the wall at A-2 is significantly increased due to the more prominent coupling effect, as its location is close to the existing building. Therefore, the deformation development at C-3 and A-2 should be focused on during the excavation process.