## 1 Introduction  
Where a city undergoes development and its population increases, a single-line tunnel no longer satisfies the travel needs of the populace. In response, the construction of additional double-line tunnels has been implemented in the development of subway lines. In recent years, the shield method has become a prevalent construction technique in the development of urban underground rail transit. This method is characterized by its focus on safety, reliability, high construction efficiency, and minimal environmental impact. The practicality and adaptability of these methods in the field of structural engineering have yielded novel insights for underground structures and related applications, as evidenced by a series of research results [1, 2]. Due to the spatial limitations inherent to subterranean environments, the clear distance between double-line tunnels is frequently minimal. Subsequent excavation of the shield tunnel will disturb the stratum once more,thereby prompting the progression of stratum deformation and consequently jeopardizing the integrity of adjacent structures. To mitigate these risks, it is imperative to elucidate the deformation laws of the ground due to shield construction and to develop precise and expeditious methods for predicting the extent and magnitude of ground settlement resulting from shield construction. The research methods are mainly divided into three categories: empirical formulas, model tests, and numerical simulation methods. For the empirical formula method, [PERSON] [3] analyzed a large amount of tunnel construction settlement data and proposed the Peck formula. [PERSON] and [PERSON] [4] proposed an empirical formula between the width of the clay and sand settling tanks and the depth of the tunnel. [PERSON] and [PERSON] [5] obtained the calculation formula of ground settlement in a double-line tunnel based on the Peck formula and superposition principle of double-line tunnels. Other settlement factors in different regions, such as tunnel depth and soil characteristics, have also received extensive attention [6; 7; 8; 9]. In relation to the model test, [PERSON] et al. [10] and [PERSON] et al. [11] studied the settlement and strain caused by the excavation of a new tunnel on the existing tunnel through the centrifugal model test. [PERSON] et al. [12] and [PERSON] et al. [13] established a model box to simulate tunnel excavation and studied the surface movement law of shield tunnel construction. In terms of numerical simulation, [PERSON] and [PERSON] [14] developed a three-dimensional numerical model of shield tunnel construction and studied the influence of various parameters. [PERSON] et al. [15] conducted a numerical study on the interaction behavior of three-parallel-tube tunnel and four-parallel-tube tunnel excavation based on the Xueshan tunnel. Taking Milan Metro Line 5 as an example, [PERSON] et al. [16] discussed the influence of double-tunnel construction on surface and structural settlement by using field measurement and three-dimensional finite element inversion analysis. [PERSON] et al. [17] simulated the construction process of the Isfahan subway tunnel using discrete element calculation software and analyzed the dynamic response of displacement and stress during tunnel construction. [PERSON] et al. [18] used the finite element ABAQUS to model an urban shield tunnel and summarized the changes in surface deformation and lining internal force. Researchers have also performed some research on other tunnels in different regions and different geology [19; 20; 21]. Compared with the other two methods, the use of numerical simulation to analyze complex tunnel construction situations can reduce the research and development cost, consider the coupling effect of multiple factors, quickly carry out many calculations and analyses, and obtain the results in a shorter period of time. Consequently, this paper adopts the numerical simulation method to study the complex working conditions.