SETTLEMENT CONSIDERATIONS FOR DESIGNING THE ALASKAN WAY TUNNEL

摘要

Washington State Department of Transportation (WSDOT) is proceeding to constructrna large-diameter soft-ground bored tunnel as the preferred replacement of thernaging and seismically deficient Alaskan Way Viaduct in Seattle, Washington. Thisrn9,000-foot-long (2.7 km) highway tunnel will have 2-lane upper and lower roadways inrna stacked configuration and will be constructed with an Earth Pressure Balance tunnelrnboring machine (EPB TBM). The tunnel contractor is providing a tunnel with an internalrndiameter of 52 feet (15.8 m) to be constructed with a 57? foot diameter (17.5 m) TBM.rnTunneling is in soil with maximum depth of cover of about 200 feet (61 m). This paperrnpresents tunneling settlement considerations for the reference design in the Design-rnBuild Request for Proposals (RFP), which was issued by WSDOT on May 26, 2010.rnDesign-Build bids were received October 28, 2010. WSDOT awarded the contractrnDecember 17, 2010 to Seattle Tunnel Partners, a joint venture of Dragados-USA andrnTutor Perini Corp., The contract’s first Notice to Proceed is expected in February 2011.