Analysis of tunnel and super structures for excavation

The nonlinear finite element method and serendipity eight nodes element are used for determining ground surface settlement due to excavation of a tunnel. A modified generalized plasticity model with a non-associated flow rule was applied for analysis of a tunnel in Sao Paulo, Brazil. A linear element with elastic behavior was used for modeling the lining. A two story building with hinged connections and XX braces, on Tehran and Houston sand, was also studied for the process, with each tunnel at different depths. Results showed an interaction between the tunnel and the building, which was evaluated in the tunnel at a 2D2D depth. However, there is no interaction between the tunnel and the super structure when it is at 3D3D depth. Also, the super structure increases the settlement due for excavation. The predicted results showed good agreement with field data from the Sao Paulo tunnel. The predicted plastic strain below the structure increases when the overburden is decreased. The settlement was almost zero at the distance of 5D5D from the center of the tunnel. When the super structure is on the ground surface, the settlement is induced between the center of the tunnel and 2.5D2.5D from the center of the tunnel; not beyond this distance.