Cairo metro network is one of the major national projects in Egypt. It aimed at developing underground transportation system to solve the severe traffic problems in Greater Cairo which includes 3 crowded governorates; Cairo, Giza and Qalyubia. The project started in the last decades of the twentieth century where 2 lines were executed. In this century, the project is expanding and more lines are constructed. The tunnel constructed for Cairo Metro Line 3 has a circular cross section that consists of a precast segmental lining thickness of 0.40 m. This paper presents a parametric study on the effects of seismic waves on the tunnel structure through numerous simulations employing the finite – element analysis. Full dynamic analyses were performed employing three different earthquake motions as well as the effect of train-induced dynamic load. Also, the induced tunnel straining actions were studied. The analysis of soil-structure interaction was done using the commercial software PLAXIS®. The results proved that the 0.40 m thick circular cross section can safely sustain the expected static, dynamic and seismic stresses.