## 6 Conclusions  
Based on the current research, numerical simulations were conducted to analyze the tunnel displacement behaviors induced by adjacent deep excavation, considering different tunnel positions outside the pit. On this basis, the influenced zone of deep excavation on adjacent tunnel displacement was divided. Then, the commonly used control measure of ground improvement was chosen to study the effect of strength, depth, and width of improved soil outside the pit on the tunnel displacement. An index of displacement control effectiveness (\(\eta\)) was proposed to quantitively characterize the control effect on tunnel displacement. Considering the control effect and engineering economy, the suggested values of strength, depth, and width of the ground improvement were provided. Finally, the control effect of ground improvement outside the pit on the influenced zone of deep excavation was evaluated using the suggested construction parameters. The conclusions obtained are as follows:  
1. Based on the displacement behaviors of the tunnel induced by deep excavation, combined with the 3-level tunnel displacement control standards of 20 mm, 10 mm, and 5 mm, the range outside the pit can be divided into: I--primary influenced zone, II--secondary influenced zone, III--general influenced zone, and IV--weak influenced zone.
2. There are limits to increasing the control effect on tunnel displacement by only increasing the ground improvement strength. Considering the control effect and engineering economy together, it is suggested that the ground improvement strength should be kept within 1.5-2 MPa.
3. An optimal value exists for the ground improvement depth outside the pit. If it exceeds this value, the contribution of the ground improvement depth to the tunnel displacement control effect will be weakened. Considering the control effect and engineering economy, it is suggested that the ground improvement depth \(h=2H_{\text{e}}\).
4. The control effect on tunnel displacement can be increased by increasing the ground improvement width. In actual engineering, it is suggested to increase the ground improvement width as much as possible if there is enough site space to allow ground improvement and ensure the safety of the tunnel.
5. After ground improvement using the suggested parameters, the horizontal and vertical displacements of the tunnel are significantly reduced, and the influenced zone corresponding to the same tunnel displacement isoline is reduced. According to different tunnel displacement control standards, the range outside of the pit is divided into: II-secondary influenced zone, III--general influenced zone, IV--weak influenced zone, and the I--primary influenced zone no longer exists.  
Conceptualization, B.L.; methodology, B.L.; software, B.L.; validation, B.L., and W.X.; formal analysis, B.L.; investigation, B.L.; resources, C.S.; data curation, B.L.; writing--original draft preparation, B.L.; writing--review and editing, C.S.; visualization, W.X.; supervision, C.S.; project administration, C.S.; funding acquisition, B.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the Natural Science Foundation of Jiangsu Province (Grant No. BK20220856), the China Postdoctoral Science Foundation (Grant No. 2021M690624), and the Jiangsu Planned Projects for Postdoctoral Research Funds (Grant No. 2021K146B).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available from the corresponding author upon request.  
**Acknowledgments:** [PERSON] from JSTI Group Co., Ltd., Nanjing 210017, China.  
**Conflicts of Interest:** The authors declare no conflict of interest.