Comparative Analysis of Tunnel Deformational Behavior under Moving Surcharge Using FLAC3D

Abstract

The effect of a moving surcharge on tunnel deformation behavior is a significant area of study. Circular and horseshoe-shaped tunnels are commonly constructed based on various geological conditions and other factors. This paper investigates the effect of a moving surcharge on the deformational behavior of both tunnel shapes using FLAC3D. The Mohr-Coulomb model is adopted for this study, considering homogenous rock material and a height-to-diameter (H/D) ratio of 1 to 5 for both tunnel shapes. All dimensions of both tunnel shapes, except for height, are kept the same. The height is varied according to the H/D ratios for both shaped models. This numerical study reveals the effect of a moving surcharge on the deformational behavior at the midpoint of the crest along the tunnel. A moving surcharge strip load is considered from both directions: along the tunnel and across the tunnel. The study observes that the effect of the surcharge at the crest of the tunnel along the tunnel is more significant than the surcharge applied across the tunnel, and the horseshoe-shaped tunnel reduces displacement due to its shape.