## 1 Introduction
Reference [26] provided a compilation of the measured data of highway tunnels, focusing on how to alleviate the deformation of highway tunnels via excavation segments. In the research and analysis of a new tunnel situated over an existing tunnel, reference [27] adopted a centrifugal model test, and reference [28] adopted a scale model test. However, while one refers to an existing shield tunnel over a highway tunnel, the other considers the parallel relationship between a new tunnel and an existing tunnel. References [30; 31] were the earliest reports of engineering cases involving tunnels that crossed existing lines. Based on the field measurement data, reference [32] studied the additional effects of shield tunneling on existing tunnels from the perspectives of additional stress and additional deformation. In contrast to this paper, the two tunnels were parallel. References [33; 34; 35; 36; 37] used theories to deduce the degree of the response of existing tunnels to new tunnels, while reference [38] focused on the interaction between the tunnel structure and soil under tunneling. Reference [39] used the FLAC\({}^{\text{3D}}\) software to predict the influence of a newly constructed tunnel on an existing one, but it was still based on the conclusions of a parallel shield tunnel. To summarize, although previous scholars have used various methods to conduct the response analysis of existing tunnels regarding nearby foundation pit excavation or shield tunneling, there are few cases of existing tunnels being excavated via side foundation pits and shield over-crossing successively, and few cases of this type of engineering have been analyzed via numerical simulations and field measurements. This is the most direct and accurate method used to observe the deformation of an existing tunnel in order to understand its deformation. The observation results can be used to alert tunnel operators to changes in the existing structure and allow them to take appropriate protection measures. This has become an indispensable monitoring tool for adjacent existing tunnel construction, and many scholars have proven the validity of this method [10; 15; 26]. At the same time, with advancements in computing power, 3D finite element software has been widely used in complex soil-structure interaction analysis [10; 41; 42]. If accurate parameters are selected, the numerical simulation results can provide tunnel operators with reasonable predictive data for the evaluation of the feasibility of construction adjacent to existing tunnels. In fact, most scholars use one or more methods to analyze the influence of foundation pit excavation on the existing operating tunnel or to assess the influence of shield tunneling on the adjacent existing tunnel, while there are few studies on the influence of the working conditions on a tunnel. Therefore, further verification is needed to determine whether numerical simulations can accurately predict the results of multiple disturbances in an existing tunnel. In this paper, numerical analysis is used to simulate the impact of a tunnel under excavation and shield over-crossingtwice, which has rarely been considered in previous studies. Combined with automated monitoring data, the accuracy of the numerical simulation results is verified in detail, and some novel conclusions are obtained. Currently, studies addressing the combined effects of excavation unloading and over-crossing disturbances on existing tunnels and similar cases are rare. The complexity of displacement, deformation, and internal forces in a tunnel undergoing multiple disturbances surpasses that of a tunnel affected by a single disturbance. Consequently, it is imperative to conduct further research on the displacement and deformation of existing tunnel structures under the influence of multiple disturbances.