# Influence of Deep Foundation Pit Excavation on Adjacent Pipelines: A Case Study in Nanjing, China
## 1 Introduction  
In urban environments, the intricate network of underground pipelines, including utilities and communication lines, is significantly affected by any nearby deep foundation pit construction [1, 2]. The excavation process can lead to pipeline stress, deformation, or damage, posing risks such as engineering infrastructure failures and road collapses. The extent of these impacts escalates with the increase in the size and depth of the excavation, highlighting the critical need for careful management and monitoring in such construction endeavors [3]. Internationalally, scholars have addressed these challenges through various methodologies, including laboratory experiment, field monitoring, analytical, and numerical simulation approaches [4]. [PERSON] et al. [5] analyzed the interaction between soil and pipelines in sandy soil using centrifuge models and finite element methods. [PERSON] et al. [6] investigated pipe-soil interactions using experimental and numerical methods. However, due to the limitations of experimental conditions and costs, laboratory research findings are limited. Finite element models can be used to simulate complex geological and engineering conditions, enabling detailed analysis of factors like excavation steps, pipeline depth, distance from the pit, and pit stiffness on pipeline deformation. [PERSON] et al. [7] developed a three-dimensional model of pipelines and pits to study deformation patterns under varying excavation parameters. [PERSON] et al. [8] combined practical engineering cases with finite element simulations to optimize pit structures by analyzing the effects of pitexavation on adjacent subway tunnel deformation and internal tunnel forces. [PERSON] et al. [9] used Plaxis finite element software to simulate the large-diameter pipeline displacement caused by pit excavation, examining the differences in horizontal and vertical displacements. [PERSON] et al. [10] conducted parametric analyses on the impact of pit construction on nearby pipelines using finite element methods that considered the small strain stiffness characteristics of soil, and they segmented zones of pit excavation impact on nearby pipelines. [PERSON] et al. [11] performed numerical analyses considering saturated and unsaturated soil excavation using an improved effective stress analysis method to study the force on and deformation of rigid and flexible pipelines. Their findings indicated reduced deformation and internal forces in pipelines during unsaturated soil excavation. [PERSON] et al. [12] used Plaxis3D software to predict the impact of tunnel construction on historic buildings in Rome. A hardened soil model with small strain stiffness was used to model the behavior of the soil, and the results of the study provided useful insights into the behavior of soil tunnel construction systems. [PERSON] et al. [13] explored the effects of deep foundation excavation on neighboring oil pipelines through numerical simulations and field tests. The rule of the changes in the pipeline-soil gap was investigated. Finally, the effect of changes in the pipeline foundation and overlying soil layer on pipeline settlement was discussed. Additionally, scholars have monitored real-world excavation projects. [PERSON] and [PERSON] [14] analyzed the impact of circular pit and subway station pit excavations in soft-soil areas on adjacent shallow-buried underground pipelines, considering pipeline stiffness, relative position to the pit, and soil properties; they proposed deformation prediction formulas based on empirical data, highlighting the decisive role of the pipeline's position relative to the pit. [PERSON] et al. [15; 16] have developed a stress prediction model for pipelines under different operating pressures, influenced by nearby pit and tunnel explosion vibrations, which is useful for assessing pipeline safety during pit blasting operations. In theoretical analyses, pipeline deformation is often modeled using the elastic foundation beam model, with the Winkler foundation model being widely used.