Numerical modeling for Selection of appropriate tunneling method in S station of Isfahan subway

Abstract

Nowadays, due to the increasing urban environments, increasing the density of surface structures and the lack of space for intra-urban transportation, the need to implement underground structures such as tunnels and subway stations in urban environments has been felt more than ever. One of the important factors in the implementation of deep underground stations in urban environments is the choice of suitable excavation methods that have a significant impact on the stability of the tunnel space during excavation, surface sinking caused by drilling, and also the long-term stability of the excavated space. In this research, considering the geotechnical characteristics of the land and the geometry of the station under study, three common methods for excavation of subway station, including NATM, STM, and cut & cover methods with support systems such as shotcrete, piles and ribs, fore polling and nailing numerically modeled and have been evaluated and reviewed for the stability of the space and tunnel wall displacement. Numerical modeling of various methods for implementing this space has been done using the finite difference method with FLAC3D software. Sensitivity analysis for changing geometric parameters of support systems was done. According to the results, the maximum displacement in the environment around the station is related to the cut & cover method and the minimum is related to the STM method with the nailing support system.

Keywords

• subway station
• natm
• stm
• cut & cover
• support systems
• numerical modeling