Numerical modelings of continuous shallow tunnels subject to reverse faulting and its verification through a centrifuge

Abstract

Although tunnels are vulnerable to Permanent Ground Displacement (PGD) due to a fault crossing, studies in assessing this intersection are limited, and most of the existing studies have focused on fault movement parallel to the tunnel. A series of numerical models with the Finite Element Method is applied here to evaluate the behavior of tunnels and reverse faults intersections. The numerical modeling results of 60° reverse faulting in free-field and tunnel mode are validated through centrifuge tests. These models are applied as reference models for the parametric study. The effects of geometrical properties, including fault angle, faulting displacement, tunnel diameter, tunnel lining thickness, and overburden soil height on the reverse fault-tunnel crossing is studied. Increasing the tunnel diameter increase the tunnel's vulnerability. The 60° fault angle causes the most damage to the tunnel. Any fluctuation in fault angle from this specific value reduces the tunnel lining bending moments.