Influence of a tunnel on the seismic response of an adjacent tall building considering dynamic interaction of Building-Soil-Tunnel system

Excavating tunnels in urban areas could have a profound effect on the site characteristics and could change the free-field motion due to many different reasons. Although the previous earthquake events have ascertained that the response of the above-ground buildings close to the tunnel will also change, this effect is not well-addressed in the national and international design building codes. In this paper, considering a fully coupled system of tunnel-soil building interaction, the presence of a tunnel on the seismic response of a two dimensional 15-story scaled benchmark building under two far- and two near-field benchmark earthquake records has been investigated. Additionally, non-linear dynamic analyses considering the material and geometric nonlinearity have been applied, and to obtain nonlinear behavior of the soil, Mohr-Coulomb failure criterion and the equivalent linear method are implemented. The interface between structural foundation and soil is simulated by normal and shear springs and, the interaction between tunnel and soil is modeled using Coulomb Friction. As a parametric study, the effect of tunnel shape, cross-sectional area, the burial depth of the tunnel, and the effect of site soil material on the seismic response of the building is evaluated by evaluating the ratio of the structural responses with the presence of the tunnel to the structural responses without the presence of the tunnel. The results showed that the maximum relative displacements of the building for soils with 320 and 150 m/s in the presence of the tunnel decrease at most 10 percent under both far- and near-field earthquake records.