Digital Design and Safety Assessment of Foundation Pit Excavation by BIM-FEM

The increasing proximity of deep excavations to existing tunnels in urban underground development necessitates accurate safety assessment and early warning mechanisms during design and construction. Traditional approaches suffer from inefficiencies in multi-source data integration, low interoperability between modeling and analysis platforms, and limited capability in capturing complex soil-structure interactions. This paper presents an intelligent building information modeling (BIM)-finite element method (FEM) collaborative workflow that enables intelligent modeling, automated data conversion, and high-fidelity mechanical analysis for the digital design and safety assessment of foundation pit excavation adjacent to sensitive tunnels. A parametric modeling framework combining Kriging interpolation and Dynamo visual programming is developed to construct high-precision 3D geological, support, and tunnel models despite sparse borehole data. A seamless BIM-to-FEM interface based on the advanced computer-aided software integrated system (ACIS) kernel and HyperMesh is implemented to ensure lossless data transfer, automated mesh optimization, and boundary condition assignment. The proposed workflow is validated through a real-world case study, showing existing tunnel deformation errors of 1.59%–4.80% and horizontal displacement increments of over 58%–72% occur during the excavation phase in weak soil layers. The accuracy of diaphragm wall deformation capture in weak soil layers reaches 97.45%. A deformation-sensitive area is defined based on a 3 mm displacement threshold. Parametric analysis further reveals that tunnel deformation decays exponentially with horizontal distance and embedment depth, and identifies critical design thresholds for deformation-sensitive zones. This framework offers an efficient digital twin solution for risk control and safety assessment in complex urban underground projects.