Three-Dimensional Responses of Tunnel to Adjacent Construction

Adjacent construction activities, such as deep excavations for basement construction, will result in stress changes that will eventually result in subsurface movement, potentially disrupting existing tunnels. The effects of clear depth below the bottom of the excavation on the adjacent tunnel due to deep excavation in a homogeneous sandy stratum have been addressed in this paper. A number of three-dimensional FE analyses were carried out to examine the impacts of deep excavation on the existing adjacent tunnel. Numerical analysis was performed using an advanced soil constitutive hardening soil model with small strain stiffness (HSS) to capture the complex interaction behaviour between deep excavation and tunnel. Investigations have been made into the induced tunnel deformation and strain in both transverse and longitudinal directions. The same study was extended to investigate the tunnel’s response to the adjacent deep excavation in stratified soil. Deformations and strains obtained from homogeneous strata are underestimated in relation to those obtained from stratified soils.