<p>Terrorist attacks are significantly increasing worldwide, targeting government agencies and urban structures to cause massive economic disruption, property damage and loss of lives. In the present study, three-dimensional finite element analysis is performed to study soil-structure interaction in twin box cut and cover tunnel under blast loading using MIDAS GTS/NX and PLAXIS 3D. The cut and cover tunnel is divided into eight zones and blast loading on each zone is calculated using an in-house developed Mathcad sheet. The peak reflected overpressure is then applied with a time function to represent the blast loading scenario. The behavior of concrete is modeled using a linear elastic material model in MIDAS GTS/NX while the linear elastic and nonlinear concrete model in PLAXIS 3D. The Mohr-Coulomb model is used for all soil layers to model linear elastic perfectly-plastic material behavior with the Mohr-Coulomb failure criterion. The finite element model is discretized to 3D tetrahedral elements with finer mesh at interface boundaries. To capture the effect of soil structure interaction, parametric studies were carried out by varying model parameters and loading conditions i.e. concrete strength, native soil type, and backfill properties. It is observed that the most vulnerable structural element for the cut and cover tunnel section is the middle wall of the structure. The displacement of the side walls is reduced due to the passive resistance of the soil in contact outside. The top slab is also observed to be affected by the presence of soil surcharge above. However, the effect is largely governed by the blast charge weight and standoff distance. The soil above the top slab experiences considerable displacement which results in differential settlement of the surrounding structures. The present paper highlights the blast load estimation process and demonstrates its application in any structural analysis software.</p>