Risk Damage Evaluation of Surrounding Buildings of O7 Station of Line7-Tehran Metro Using Relative Stiffness Method

Tunnel construction in soft ground causes ground displacements around it. Displacements influence surface and subsurface structures in urban areas and cause serious damages and injuries. So prediction of ground deformations and involved possible damages on surrounding structures are major parts of designing and planning in soft ground tunnelling. In this paper, O7 station of line7- Tehran metro was modeled using FLAC3D. This station is located in residential and commercial region with high density. Station excavated using underground method. At first, a gallery was excavated in middle of station in order to access and excavation of lateral piles and concrete arcs. To control the settlement, piles and concrete arcs created as temporary support with 1.2m spacing. In the next stage inside of station excavated and permanent support installed. It found that two buildings located in influence area of the station. Since the obtained value of settlement for both buildings was higher than 10mm, so in first stage assessment of risk damage these buildings were in unsafe region. Then second stage assessment of risk damage conducted using relative stiffness method. In this stage, building located in safe region. Therefore, It can be concluded that excavation of station has no risk damage on surrounding structures.