## 1 Introduction
Many researchers have undertaken a lot of research on the deformation and settlement of double-line tunnel construction. [PERSON] [22] first studied the ground settlement characteristics of a double-line tunnel based on field monitoring data, which laid the foundation for the subsequent research on double-line tunnels. [PERSON] et al. [23; 24] discussed the influence of the distance between the two tunnels on the ground settlement during the construction of the second tunnel. [PERSON] et al. [15; 25] pointed out the relationship between the relative distance of the tunnel and the strength of the interaction between them. [PERSON] et al. [26] studied the ground settlement curves at different depths above the tunnel during the excavation of the second tunnel when the first tunnel was completed. [PERSON] et al. [27] used model testing and numerical simulation to investigate the influence of tunnel excavation on existing tunnels. Based on field data and numerical calculation, [PERSON] and [PERSON] [28] summarized the normalized curve of surface subsidence during the excavation of double-line tunnels and compared the influence of distance and buried depth between the two tunnels on surface subsidence. [PERSON] and [PERSON] [29] analyzed the field data and pointed out the influence of the second tunnel excavation on the ground settlement when the double-line shield tunnel is excavated in front and back parallel shield tunneling. [PERSON] et al. [30] studied the earth pressure mode, the derivation of safe clearance, and the influence of parameters in the excavation of shallowly buried double-line shield tunnels with small spacing. [PERSON] et al. [31] established a tunnel settlement propagation model based on the analysis of surface and subsurface settlement. [PERSON] and [PERSON] [32] investigated the influence of excavation, construction sequence, and various geometric parameters on the soil settlement of shallow offset double tunnels in clay. In summary, previous studies have primarily focused on factors such as tunnel size, buried depth, tunnel distance, and soil pressure mode that affect double-line tunnel ground settlement. Moreover, the majority of researchers have focused on relatively simple geological conditions and have given less consideration to complex construction and geology. While the extant research results on tunnel excavation offer a useful reference point for the safe construction of tunnels, the large differences in geological conditions between regions must be taken into account. In the context of complex geological conditions, the extent of land subsidence of a near-buried double-line tunnel under diverse excavation conditions remains to be fully elucidated. Therefore, based on the working condition of an underground near-buried double-line tunnel, this paper utilizes the numerical method to establish a model to analyze the variation law and influence order of ground lateral settlement of deep-buried double-line tunnels under different tunnel lateral spacing and longitudinal excavation spacing. The variation curve of ground settlement with the excavation step is delineated, and the variation law of ground settlement with the excavation step is analyzed. The horizontal deformation law of the ground of the double-line tunnel is summarized. Finally, the calculation formula of ground transverse settlement of double-line tunnels with different tunnel spacing is analyzed by linear fitting.