3D Effects of Surface Construction Over Existing Subway Tunnels

Abstract

A 3D elasto‐plastic finite element model is used to examine the effect of construction over two existing tunnels. Tunnel deformation and the change in lining shape are compared with the field measurements of the York‐Mills Centre project constructed in 1989 over an existing Toronto subway tunnel. The criterion for potential damage to the tunnel liner is established based on the extreme fiber stresses of the lining. Typical 2D plane strain analyses were also conducted to investigate the importance of the 3D analysis in this case. Reasonable agreement is found between the observed field measurements and the predicted results using the 3D numerical simulation.