With the increasing utilization of urban underground space in densely populated cities, it is crucial to understand the interactive impact of the excavation sequence on the excavation group of foundation pits. The foundation pit of Tianta Station of Tianjin Metro Line 7 was adjacent to a deep foundation pit of an apartment, which provided a good case for the study of simultaneous excavation of foundation pits. In this paper, based on two deep foundation pit excavation projects, a finite element model was established to better understand the mutual influence of simultaneous foundation pit excavation. The responses of the two deep foundation pits under five different excavation sequences were investigated, including the horizontal displacement of the ground‐connected wall and the displacement of the top of the wall, the settlement of the ground surface, and the supporting axial force of the basement floor slab. The position of the maximum horizontal displacement in different modes is the same, and the shape of the deformation curve was fish‐bellied. When both pits B and C were excavated simultaneously, the surface settlement between adjacent pits was smaller than in other working conditions. Mode 5 is optimal among these five modes, in which not only the construction progress is the fastest but also the underground wall deformation and the ground settlement are relatively small. The findings and lessons learned from these two adjacent pits, both of which were constructed using the cap‐and‐reverse method, can help professionals optimize excavation design and construction, as well as performance prediction and control.

The double‐row capsule grouting (DRCG) is an innovative technique which can restrain the horizontal and vertical tunnel deformations induced by excavation simultaneously. The real‐time and active control capacity of DRCG can overcome the shortcomings in invariance and inefficiency of the traditional protective approaches. However, the performance of DRCG and the prediction method of control effectiveness have not been investigated. A numerical analysis using the hardening soil model with small‐strain stiffness (HSS model) is conducted to investigate the influences of the relative buried depth and the grouting volume of capsule on the control effect of DRCG in relation to the restoration ratio of horizontal deformation (R_h), and restoration ratio of vertical deformation (R_v). A polynomial relationship between parameters and restoration ratio is observed. Furthermore, a dimensionless formula, developed from hypothetical cases, shows a high conformity between predicted and numerical results. It can accurately predict the control effectiveness of DRCG.

Small‐radius curved tunnels are increasingly adopted in urban areas to navigate around existing infrastructure. However, their excavation induces more complex and asymmetric soil displacements compared to straight tunnels, especially in S‐shaped alignments where two consecutive reverse curves interact. This study uses 3D numerical modelling (Plaxis 3D) to compare soil settlement patterns from straight, single‐curve and S‐shaped tunnels in soft clay. Results show that the S‐shaped tunnel causes the greatest settlement and the broadest influence zone, with a clear coupling effect between two consecutive reverse‐curvature curves leading to a wavy settlement profile. The settlement field is notably asymmetric, influenced by the intersection angle between the tunnel axis and adjacent infrastructures. The risk assessments of nearby infrastructures are highly dependent on their spatial relationship with the S‐shaped tunnel. These findings highlight the heightened geotechnical risks associated with S‐shaped curved tunnels and underscore the need for tailored design and monitoring strategies in urban tunnelling projects.