Investigation on Ground and Lining Response Due to Construction of a Horseshoe-Shaped Tunnel Considering Staged Excavation

This study investigates the surface and lining responses that result from constructing a horseshoe-shaped tunnel in mixed ground conditions, considering both uniform and topographic variations in ground profiles through three-dimensional (3D) finite element analysis. The Hardening Soil (HS) model and Mohr-Coulomb (MC) model have been considered for evaluation of the ground and lining responses. Different parameters, including surface settlement, ground volume loss, lining deformations, tunnel convergence, and the zone of influence, are evaluated through numerical investigation and compared with field measurements. The results show that the MC model underestimates the surface settlement, surface volume loss, and tunnel convergence, while the HS model reasonably agrees with the field observations. The results also indicate that the variation of ground topography significantly impacts the ground settlement and tunnel lining responses compared to a uniform ground profile. The zone of influence, width of inflection points, and trough width are estimated from numerical analysis and compared with the available literature. The study shows that the use of an appropriate soil model, material properties, and numerical modeling procedure reasonably estimates the post-construction parameters of the tunnel and ground. Different details of tunnel construction, support systems, numerical modeling procedures, field, and numerical results are reported in the current study.