Investigation on Effect of Full Face Excavation of Subway Tunnel on Adjacent Buildings (Case study: 1st Line of Tabriz Subway)

In most cities, the infrastructures need to be increased due to the population growth. Given that the large cities are overcrowded and there is less space for surface transportation, the creation of subsurface structures like tunnels is essential. The excavation of tunnels may cause diverse problems, such as settlements of surface buildings. So determining the amount of settlements caused by underground excavation and comparison with the amount of allowable buildings settlement is important. Methods of settlement prediction are divided into experimental, analytical and numerical methods. In this study, initially the ground surface settlement is evaluated by using the experimental and analytical methods in green field condition (without building existence) and then the effect of buildings existence on the changes in ground surface and tunneling impact on the deformation of the building caused by this movement are considered by numerical method. In this research, the part of shallow tunnel of the first line of Tabriz subway is studied. The numerical modeling has carried out by PLAXIS 3D TUNNEL. The results of numerical modeling show that the amount of the settlement caused by tunnel excavation reduces with the increase of the stiffness of foundation buildings. If building cross sectional area is extensive, the foundation settlement would be low and more uniform. Surface settlement curves show that settlement value reduces and settlement zone increases with the increase depth from first section to second section in the analytical method. However, this trend is reversed for the numerical method. It was also showed that passing the tunnel have negligible impacts on the buildings studied.