Research Progress on the Influence of Foundation Pit Excavation on the Deformation of Underpass Tunnels

When there is an underpass tunnel beneath a foundation pit, the difficulty and risk of the foundation pit engineering design and construction are significantly increased. The unloading effect caused by the excavation process of the foundation pit will alter the stress state of the surrounding soil, which can easily induce large deformation of the underlying tunnel, thereby negatively affecting the normal operation of the tunnel. The deformation of the underpass tunnel caused by foundation pit excavation is influenced by many factors. Current studies focus on single aspects and lack systematic analysis and discussion. In particular, the applicability analysis of different theoretical models and numerical methods for calculating the deformation of underpass tunnels caused by foundation pit excavation is still rarely reported. This paper systematically reviews this topic and explores the applicability and effectiveness of various analysis methods. Among them, the Kerr model is a relatively suitable foundation model for studying the deformation of underpass tunnels caused by foundation pit excavation. For numerical simulations involving large deformations and high precision, ABAQUS is more appropriate, while for large-scale numerical simulations, Midas/GTS is more suitable. Meanwhile, the research progress of artificial intelligence in analyzing the impact of foundation pit excavation on underpass tunnel deformation is discussed. Current related research mainly focuses on constructing artificial intelligence-based soil constitutive models, combining traditional finite element models with big data and machine learning methods to predict the impact of foundation pit excavation on underpass tunnel deformation.