Drilled shafts have been installed by Malcolm Drilling to form the secant pile retaining walls to support the 400 ft x 80 ft x 80 ft launch pit for the SR 99 tunnel boring machine on the Alaskan Way Viaduct Tunnel Replacement Project in Seattle. Excavation has commenced on the pit in preparation for the launch of a world record 57.5-ft diameter TBM (until Russia launches a planned 63-ft TBM). The Seattle Times article indicates there are a total of 1400 drilled shafts in the pit walls and nearby, but a press release by WSDOT indicates the walls are comprised of approximately 200 drilled shafts. [Source: Seattle Times via ASCE SmartBrief. Image: WSDOT Flickr]
Related Articles
Brightwater tunnel inches through toughest stretch toward finish
February 8, 2011
rockman
Project Related
Comments Off on Brightwater tunnel inches through toughest stretch toward finish
Viaduct Inspections Show Settlement Problems Long Before Tunneling
February 19, 2015
rockman
Project Related
Comments Off on Viaduct Inspections Show Settlement Problems Long Before Tunneling
Bertha – The World’s Largest Tunnel Boring Machine
Perhaps you’ve heard of Bertha, the World’s Largest Tunnel Boring Machine or TBM? She’s currently working her way underneath Downtown Seattle, excavating the Alaska Way Bored Tunnel to replace the aging Alaska Way Viaduct. This $2 Billion megaproject is an incredible feat of engineering on so many levels. I was in Seattle in September for the Association of Engineering Geologists annual meeting, and was fortunate enough to attend a field trip to see the launch pit and Bertha before she began her tunnel drive. It was an unforgettable experience for this engineer! In this article I give an overview of the project and Bertha herself, discuss some of the geotechnical features, and share my photos and video. Check it out!