## 5 Conclusions  
In this paper, a 3D finite element model with complex shapes was developed using HSS and HB constitutive models to study the effect of large deep foundation excavation on the underlying complex intersecting tunnels. The model uses multiple methods to determine the geotechnical parameters and it was rationalized based on the field data. The simulated and measured results are in good agreement for all three stages. The deformation and internal force response of the tunnel are analyzed in depth. Based on the above, the following results were obtained.  
1. The effect of excavation on the tunnel is mainly distributed near the excavation area and has a normal distribution trend. The displacement of the tunnel below the center of the excavation is the largest, and the tunnel outside the 2 times excavation scope is almost unaffected. Therefore, the tunnel monitoring points should be arranged within the 2 times the excavation scope and encrypted at the center. In addition, the maximum vertical displacement of the tunnel is 3.1 mm and the maximum horizontal displacement is 0.87 mm, so the monitoring should focus on the vertical displacement of the tunnel.  
Figure 14: Tunnel deformation diagram.  
Figure 13: Nephogram of tunnel lining moment.  
Figure 15: Non-intersection tunnel stress reduction.  
In the tunnel section, the displacement distribution is not uniform, and the uplift of the top of the tunnel is much larger than the bottom, so the monitoring points of vertical displacement should be mostly distributed at the top. The stress analysis of the tunnel section shows that the stress change in the tunnel side lining is the largest, followed by the top of the tunnel. Therefore, the tunnel cracks and stress monitoring points should be located at the side and top of the tunnel.
3. There are stress concentrations and larger deformations in the tunnel intersection area. This is because the flat profile of the intersection zone is more prone to deformation under unloading than the nearly circular profile of the non-intersection zone. Therefore, the stress and displacement in the intersection zone should be closely monitored.
4. The tunnel is flattened by earth pressure at the beginning and then slightly pulled up during excavation. These two deformation patterns are diametrically opposed and cause significant changes in the top displacement and side lining stresses of the tunnel.
5. Future studies could consider in more detail the effects of pit dewatering, pit support forms, excavation sequence, and tunnel support methods on tunnel stresses and displacements.  
Conceptualization, G.D. and Z.L.; methodology, Z.L.; validation, G.D.; formal analysis, H.W. and Z.Y.; investigation, X.Z.; resources, X.Z.; data curation, S.C.; writing--original draft preparation, Z.L.; writing--review and editing, G.D.; project administration, X.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Science and Technology Research and Development Project of CSCEC (CSCEC-2020-Z-21), and the National Natural Science Foundation of China (NSFC Grant No.s 52078128, 51878160).  
Not applicable.  
Data Availability Statement: Data are contained within the article.  
The authors declare no conflict of interest.