Stability analysis of koohin rail way tunnel considering time dependent deformation

In this paper, by choosing Koohin tunnel and extracting physical, mechanical and the creep parameters of rock mass surrounding the tunnel, stability analysis is performed in the usual way,then by using two analytical solutions(Panet’s model and the modified model),and also numerical method, tunnel creep analysis is carried out and the results are compared. The effective parameters on creep behavior of tunnels are also investigated. Then after, to clear out the effect of parameters such as: k0(horizontal to vertical stress ratio), k(bulk modulus)on time dependent behavior oftunnel, time sensitivity analysis,isperformed. For this purpose, FLAC program that has the ability to model the creep behavior of tunnels is used. Furthermore, Panet analytical model for considering time dependent behavior of tunnel is used in this study, and a modification to this model using Hook-Brown nonlinear criterion is applied, and the result are compared. The analyses performed on time dependent behavior of koohin railway tunnel(Iran)reveal that:Bulk modulus has no effect on the time dependent displacement of tunnel. With increasing horizontal to vertical stress ratio, time dependent displacement of tunnel is decreased. Analytical relationships presented (Panet’s model and the modified model) predict the time dependent behavior of circular tunnels very well