## 3 Comparative Analysis of Monitoring Data and Numerical Simulation
### Space-Time Deformation Analysis of Foundation Pit Structure
#### 3.3.3 Spatio-Temporal Deformation Analysis of Land Surface Subsidence  
In Figures 11 and 12, the deformation monitoring values and numerical simulation values of the surface settlement and displacement monitoring points at different profile  
Figure 10: The relationship between the settlement of the roof of the ground wall and the depth of excavation [7; 24; 27; 28]. Figure 9: The monitoring deformation value and numerical simulation value of the south ground connecting wall. positions of the foundation pit during the whole construction process are given, in which the positive is the settlement and the negative is the uplift. As can be seen from the figure, the deformation monitoring values and numerical simulation values of the north and south surfaces both show several shape deformation characteristics, indicating that the established finite element simulation model can better reflect the deformation characteristics of the structure in the super-deep foundation pit. With the excavation and the construction of the foundation pit, the settlement deformation value increases first, then decreases and then increases, and the settlement rate increases when the settlement deformation decreases. On the one hand, due to the reduction of earthwork excavation rate, sand has the \"lag\" of stress transfer [29,30], and the surrounding soil has sufficient time to release the stress. In addition, due to the application of each floor, the flexural deformation of foundation pit envelope can reduce the settlement deformation of surface soil. To better show the deformation law of surrounding surface settlement with excavation construction, Figure 13 shows the maximum 8 vmax of surface settlement at each excavation  
Figure 11: Surface deformation monitoring and numerical simulation values on the north side. Figure 12: Surface deformation monitoring and numerical simulation values on the south side. depth and its relationship. Compared with relevant research results, it can be seen that the surface settlement caused by the excavation of this super-large deep foundation pit ranges from 0.2% to 2.3% He. The upper limit is much larger than Clough [31] and Tan [32] Tan Statistical range of surface subsidence in hard clay strata and Xu Zhonghua [27]. The statistical surface settlement range is similar to the deep underground foundation pit engineering in the soft soil area of Shanghai, but the lower limit meets the distribution of foundation pit specifications [33] The recommended surface settlement control value when the environment level is 1, where the upper limit of surface settlement is located on the north side of the foundation pit, and the lower limit is located on the south side of the foundation pit [29]. Figure 14 shows the distribution of the post-pit surface settlement perpendicular to the envelope structure, where \(\delta\
u/\delta\)vmax is the ratio between the surface measuring points outside the pit at each construction stage and the maximum settlement deformation during the total construction process, and S/He is the ratio between the surface measuring points outside the pit and the final construction depth. Through comparison with other existing engineering experience curves [27; 31; 32; 33], it can be found that the main influence range of surface settlement and deformation in this project is within four times the excavation depth (He), and the reasons for this are analyzed as follows: (1) The maximum excavation depth of the foundation pit is 35 m. Compared with the conventional deep foundation pit, the dewatering depth of the foundation pit before excavation is nearly doubled, and the dewatering results in the early deformation of the foundation pit envelope and the significant influence of the ground settlement around the foundation pit; (2) The foundation pit is 350 m long and 120-190 m wide.