## 5 Conclusions  
This paper utilizes a combination of on-site monitoring and numerical simulation to investigate the construction of a subway viaduct beneath a road foundation pit that is 20.2 m deep and 495 m long. The main findings of this research are as follows:  
1. Based on the analysis of on-site monitoring data, the deformation characteristics of the bridge structure are as follows: The maximum vertical deformation value of the bridge substructure is 0.8 mm, indicating uplift deformation; the maximum transverse deformation value is \(-0.5\) mm, indicating inward deformation towards the excavation area. These deformations are observed specifically at the pile foundation supporting Pier 7#. 2. Based on the analysis of on-site monitoring data, the track structure exhibits a deformation pattern. The track structure experiences a maximum vertical uplift deformation of 0.8 mm. Additionally, there is a maximum transverse deformation of \(-0.5\) mm, which is directed towards the inner side of the excavation and corresponds to the maximum deformation of the bridge pier. 3. By comparing and analyzing the results of numerical simulations and on-site monitoring data, it has been observed that although there is some discrepancy between the two, the deformation trend is essentially identical. This suggests that the numerical simulation analysis method is a more cost-effective solution for accurately predicting the deformation of the bridge and track. 4. By utilizing numerical modeling and manipulating the values of enclosure structure parameters such as the insertion ratio of embedment depth, pile diameter, and pile distance, a comprehensive analysis is conducted on the sensitivity of the deformation of the piers at the adjacent road pit to these parameters. The results show that the effects of the embedment depth of the enclosing piles, the diameter of the enclosing piles and the spacing of the enclosing piles on the deformation of the piers decrease in that order. 5. As the insertion ratio of the embedment depth of the enclosing pile and the diameter of the enclosing pile increase, the deformation of the piers decreases in magnitude. Conversely, as the distance of the enclosing pile increases, the deformation of the piers increases in magnitude. The vertical and transverse deformations of the piers are logarithmically correlated with the ratio of the depth at which the enclosing pile is inserted, the diameter of the enclosing pile, and the spacing between the piles. 6. This thesis is limited to the study of the deformation effects of pile buttressing and foundation construction only under the soil conditions of alternating clay, silt, and fine-to-medium sands and lacks relevant studies on the stratigraphy of coastal areas or other special soil areas. Conceptualization, H.P. ; Methodology, H.P. ; Validation, H.P. ; Formal analysis, S.T. ; Investigation, S.T. and L.Z. ; Resources, S.T. and L.Z. ; Data curation, S.T. and G.W. ; Writing--original draft, H.P. ; Writing--review & editing, B.M. ; Visualization, G.W. ; Supervision, G.W. ; Project administration, S.T. ; Funding acquisition, S.T. All authors have read and agreed to the published version of the manuscript. This research was funded by Science and Technology Research and Development Project of China State Railway Group Co., Ltd. grant number L2023G007, L2022G007, Science and Technology Research and Development Program Project of China Railway Group Limited grant number 2020-Special-02, 2021-Special-08 and Hunan National Natural Science Foundation grant number 2021 JJ30053. Not applicable. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author. **Conflicts of Interest**: Author [PERSON] was employed by the company China Railway Group Limited.