Authors: T. Gregor, M. Geary, B. Garrod
Proceedings of the 4th International Flac Symposium 29-31 May 2006 Madrid, Spain
Abstract
Hatch MottMacDonald and Jacobs Civil with Dr. G. Sauer Corporation were responsible for the civil and structural engineering design of the Beacon Hill station in Seattle. The station is a part of the Sound Transit Link Light Rail project and consists of a complex system of shafts and tunnels. The station patron access and ventilation tunnels were designed for the sequential excavation method of construction. FLAC 3D (Itasca 2002) was extensively used in the design of the shafts and tunnels located in variable soil conditions.
Modeling included a representation of the excavation process in which the tunnel cross-section is incrementally excavated and supported in small steps, with non-linear soil properties considered. Numerical analysis was used for the design of both, the initial temporary and the final linings. Modeling of various tunnel and shaft junctions was perhaps the most analytically challenging part of the project.
