Authors: C. Tattersall, T. Gregor and M. Lehnen
North American Tunnelling 2004 Conference, May 2004
Abstract
To help reduce construction risks for the up-coming Beacon Hill Tunnels & Station contract, the project owner, Seattle’s Sound Transit, made a decision to construct a test shaft into main soil strata at the location of the future Beacon Hill station. In addition to evaluating the performance of the ground from the point of the station constructability using the Sequential Excavation Method (SEM), the construction of this shaft provided an opportunity to evaluate the numerical modeling approach used in the design of the station excavation, prior to the start of the station construction. Observations made during the test program resulted in a fundamental change in the selected construction methodology of the station shafts. The results also indicate that is feasible to use 3-dimensional structural analysis to predict behaviour of SEM-constructed shafts in soft ground.
