Three-Dimensional Centrifuge Modeling of Ground and Pipeline Response to Tunnel Excavation: Fid-Bau Portal

Three-Dimensional Centrifuge Modeling of Ground and Pipeline Response to Tunnel Excavation

Shi, Jiangwei / Wang, Yu / Ng, Charles W. W.

Tunnel excavation inevitably induces stress changes in the surrounding soil leading to significant ground movements and additional stress in nearby pipelines. Most previous studies simplified tunnel–pipe interaction as a plane strain problem and focused on the case in which the pipeline intersects the tunnel perpendicularly. In this study, centrifuge tests were conducted to investigate the three-dimensional response of the ground and pipeline to tunneling, considering different pipeline orientations with respect to the tunneling direction. When the tunnel face was located within $\pm 1.25 D$ (tunnel diameter) away from the monitoring section, the ground settlement and pipe strain induced were more than 95% of the maximum recorded. When the pipeline intersected the tunnel perpendicularly, the maximum pipe strain always occurred above the tunnel centerline. However, when the pipeline intersected the tunnel at an angle of 60°, the location of maximum pipe strain shifted as the tunnel advanced. The maximum tunneling-induced pipe settlement and strain were up to 20% greater in this case than when the pipeline intersected the tunnel perpendicularly. The pipe settlement and strain may be underestimated if an oblique intersection is simply taken as a perpendicular one.