Study on the Influence of Different Excavation Sequences of Complex Group Foundation Pits on Subway Stations

To investigate the deformation effects of different excavation sequences on subway stations adjacent to complex group foundation pit projects, this study, leveraging an actual project in Changzhou, conducted numerical simulations using the finite element software PLAXIS 3D. By comparing the deformation results of six different excavation sequences, a systematic analysis of their impacts on subway stations was conducted. Results reveal a noticeable “cumulative effect” in the deformation of subway stations and shield tunnels due to the excavation of group foundation pits, with deformation increasing gradually as subpits are excavated. Displacement variations are closely associated with the distance and volume of soil unloading. Notably, within a certain range, altering the excavation sequence of adjacent pits has negligible effects on deformation. Thus, adhering to the excavation principle of “far before near, shallow before deep, small before large,” rational excavation sequencing can effectively mitigate adverse impacts of group foundation pit projects on adjacent subway stations, thereby, bearing crucial significance for the safe operation of subway stations.