Document Type : Geotechnical Earthquake Engineering
International Institute of Earthquake Engineering and Seismology (IIEES), Tehran
The permanent ground deformation during the earthquake faulting induces moderate to severe damages to the underground tunnels. The majority of the investigations on the behavior of the tunnels against fault offset were in the rock medium. There is very little available in the literature about the fault-tunnel interaction in alluvial soil. This paper has studied the interaction between a continuous tunnel and reverse faulting within a dense sandy alluvial deposit. An experimental centrifuge test, alongside the numerical modelling, has been utilized for this purpose. It has been shown that the longitudinal strains of an infinite tunnel were much higher than that of a finite length tunnel. The results have also displayed that there are critical cross-sections along the tunnel's length that maximum curvatures, moments, shears, and axial forces occur in them. The numerical parametric study on the variation of the Fault Zone Width (FZW) and reinforcement content (rs) have shown that higher rs values would be more useful in tunnel resistance against faulting. Besides, smaller FZW will make higher deformations, moments, and forces in the concrete lining. The optimum rs value has been obtained as 4%.