Seattle Light-Rail Tunnel Likely to Break Ground This Year
Failures
Tunneling ground loss sinkhole opens in Beijing street, swallows truck
On April 26, a sinkhole opened up in a busy Beijing street in China’s capital city, swallowing up a truck. According to news reports, the driver and passenger jumped out of the vehicle before it […]
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)
Standards and Codes
US House Passes National Tunnel Inspection Program
The US House of Representatives passed legislation approving a national tunnel inspection program. This of course came about as a result of a fatal accident from 2006 in a tunnel on Boston’s Big Dig project where a concrete ceiling tile fell on a car killing one person. More after the break.