The objective of the study is to investigate the influence of seismic analysis of tunnel systems (single
and twin tunnels). The seismic analysis is significant for tunnel projects in urban cities to avoid the
collapse of tunnels in this crowded city due to displacements generated as a result of earthquake
waves. A case study is The Greater Cairo metro line No.4, Phase No.1. To evaluate the influence of
seismic waves on single and twin tunnels, four cases were simulated, the first case of a single tunnel
and three cases of twin tunnels. For more serious understanding of the issue of seismic waves on
twin tunnels, the horizontal, vertical and diagonal alignment are analyzed.. Total displacement was
presented for tunnel systems. Moreover, induced internal forces in tunnel lining have been
computed. The paper presents a two-dimensional model using numerical simulations by PLAXIS
program. Based on the calculated result, a higher displacement occurs in tunnel lining during the
earthquake. The maximum change of internal forces during an earthquake occurs in shear force, then
bending moment. Moreover, the normal force of tunnel lining is less affected by seismic actions.
|
