Second Issue of International Journal of Geoengineering Case Histories [Official This Time]
News
Building the Tunnel Behind Bertha
This is a great little time lapse video from WSDOT that shows the construction of the tunnel behind the Bertha’s disassembly pit for the Alaska Way Viaduct Replacement Project.
Project Related
Video: Golder’s Tunneling Solution in Toronto for Difficult Ground Conditions
Golder Associates posted the video below describing some of their work on the York University Subway Tunneling Test Monitoring Project, part of the larger Toronto-York Spadina Subway Extension Project in Toronto, Ontario, Canada. The tunnels […]
Project Related
Voids Open as a Result of Tunneling Under Seattle’s Beacon Hill
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)