Launch Pit Retaining Walls Completed for SR 99 Tunnel in Seattle

August 6, 2012 rockman Project Related Comments Off on Launch Pit Retaining Walls Completed for SR 99 Tunnel in Seattle
Malcolm Drilling prepares to drill secant pile drilled shafts for SR 99 TBM launch pit.

Malcolm Drilling prepares to drill secant pile drilled shafts for SR 99 TBM launch pit.

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]

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Failures

Drilled shaft rig falls into hole – Iowa

June 3, 2008 rockman Failures Comments Off on Drilled shaft rig falls into hole – Iowa

On May 15 a drilled shaft rig operated by Mid America Drilling Corp was nearly swallowed by the 9-ft diameter hole it was drilling for a cell tower foundation near Harlan, Iowa. Fortunately nobody was injured and the truck did not suffer any significant damage.

In Arizona, the standard of practice is to use a temporary surface casing to prevent dangerous failures like that. I once saw pictures of a drilling contractor superindendent almost get sucked into a collapsing shaft, even with the temporary casing. Pretty scary stuff. Source: Harlan Tribune. (Photo by Samantha Bruck) 

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