Shannon Wilson

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Voids Open as a Result of Tunneling Under Seattle’s Beacon Hill

May 7, 2009 rockman Comments Off on Voids Open as a Result of Tunneling Under Seattle’s Beacon Hill

image The Seattle Times (hat tip to ASCE SmartBrief) has reported that seven voids have been discovered above the Beacon Hill Tunnel with one opening up at the ground surface. The tunnel is being constructed by Sound Transit, the area’s transportation agency as part of a roughly $2.6 billion (yep, billion) light-rail project connecting downtown Seattle with the University of Washington and SEA-TAC airport. The voids were a result of running sand pockets in the otherwise stable clay units that were encountered by the tunnel boring machine or TBM. These voids migrated up like a chimney with one reaching the surface, almost 160-ft above the tunnel. This void was apparently 21-ft deep and opened up in a resident’s front yard and could have easily swallowed her up as she noticed it while gardening. The other voids were discovered at a depth of 20- to 65-ft below the ground surface. More after the break. (Illustration from Seattle Times)

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Geotechnical Engineering of the new Tacoma Narrows Bridge

October 8, 2007 rockman Comments Off on Geotechnical Engineering of the new Tacoma Narrows Bridge

When you hear about the Tacoma Narrows Bridge, most people may think of the old Galloping Gertie footage (just for fun, I’ll add some video after the break). Of course the original bridge collapsed in 1940 shortly after opening. A new bridge was completed in 1950, and a second bridge was just opened to traffic on July 15, 2007. Gerard Buechel, the president of Shannon Wilson, examines the geotechnical challenges of constructing this massive bridge in an article post on DJC.com. Imagine constructing a 20-story reinforced concrete building, now imagine constructing it entirely under water! Read on for the link to the article and Galloping Gertie video. (Photo  by frarytd)

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