Seismic Site Response Analysis of a Cairo Metro Tunnel

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.