Deformation analysis of existing tunnel using finite element method during construction of a full-length excavation pit

Abstract

The development of underground space has been and will lead to severe intersections between works, especially intersections with existing subway tunnels. When constructing a foundation pit, in addition to controlling the risks of construction, ensuring the safety of the existing tunnel is also an important technical issue. This article is based on the actual project at urban railway project in Ho Chi Minh City. Here, the underground culvert is constructed above the existing shield tunnel, intersecting the center line with the tunnel is orthogonal. On the basis of using the finite element method with a 3D analysis model, the authors evaluate the behavior of a TBM (Tunnel Boring Machine) tunnel when constructing a full-length culvert. According to the model analysis results, the foundation pit construction process causes a vertical displacement significantly larger than the horizontal displacement of the tunnel. Simulation results are also the basis for evaluating construction methods and service facilities in the process of monitoring the displacement of the existing tunnel.