Utah State Capital Seismic Base Isolation
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ASCE 2010 OCEA Award Finalist Projects Full of Geotechnical Engineering Challenges

Utah State Capital Seismic Base Isolation I was reading the ASCE News, January edition which announced the 5 finalists for the 2010 Outstanding Civil Engineering Achievement (OCEA) Award and I was struck by the significant geotechnical engineering and geoengineering components of these projects. Read on as I highlight some of things hidden beneath the ground of these remarkable projects. […]

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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)