Geotechnical Conditions and TBM Selection for the Bay Tunnel
Abstract
San Francisco Public Utilities Commission is planning to replace 5 miles of pipeline under San Francisco Bay. The tunnel will be constructed using an Earth Pressure Balance (EPB) TBM and will be the first TBM-driven tunnel under the Bay. The alignment passes under environmentally sensitive habitats, through interbedded layers of sands and clays, and through a buried bedrock ridge. This paper discusses the geotechnical characterization and anticipated tunneling conditions and presents the analysis of various construction methods that resulted in the selection of an EPB TBM. Considerations related to tunneling with an EPB TBM are described in detail, including ground conditioners, TBM cutterhead wear, muck control, and squeezing ground.
2008
North American Tunneling Conference (NAT) Conference Proceedings
Luke Erickson
Jacobs Associates
Peter Raleigh
Jacobs Associates
Victor Romero
Jacobs Associates