Optimization of Complex Cross-Section Metro Tunnel Excavation and Its Influence on Building

A 3D numerical model for complex cross-section tunnel and building was set up based on the FLAC3D,and five construction methods were optimized by numerical simulations to determine the optimal construction method by taking subsidences of ground surface and the building and stress in the structure as the optimal object.The optimal construction method was adopted to excavate the tunnel,plastic areas induced by excavation using the optimal construction method were predicted,and corresponding pre-reinforcement measures were given.The subsidence characteristics and maximum subsidences of ground surface and building foundation in different excavation periods under the condition of pre-reinforcement plastic areas were forecasted.The differences between the subsidence curved surfaces of ground surface and building foundation were comparatively analyzed.The safety of the building and key structures of the tunnel in the whole excavation process was evaluated.The simulations results and in-site measured data have the same regularities to provide an important technical support for environment control of metro tunnel excavation with complex cross-sections.