Construcation Period
February to June 2009
January to April 2010
Client
Owner: Utah Department of Transportation
General Contractor: Kiewit/Clyde, JV
Services
Drilled Shafts
31 EA 9 ft Dia up to 130 ft in depth
3 EA 6.5 ft Dia up to 97 ft in depth

PROJECT OVERVIEW
EXPRESSLink will increase capacity to I-5 by adding express lanes in each direction from 500 North to the north interchange in Davis County. Construction began in November 2088 and is expected to complete in Fall, 2010. Bridges at U.S. 89, Beck Street, 1000 North and 800 North will be replaced. The bridges at 800 North and 1000 North will be replaced by one bridge at 1000 North. UDOT is using a Design-Build Construction method that overlaps the two processes typically done in sequence. Design-Build saves money and cuts overall construction time nearly in half.

BENEFITS OF ROTATOR OSCILLATOR SYSTEM

• Very loose and unstable soil can be stabilized to great depth.
• Vibration-free installation of temporary or permanent casing vital due to close nature of railroad tracks and proximity of underground utilities.
• Proven track record for better quality product (less shaft integrity problems).

CONSTRUCTION DETAILS

The Beck Street Bridge consisted of 24 each 9 ft diameter shafts with depths up to 135 feet. The project was unique in that the shafts were tip grouted upon completion. The designers were able to account for less settlement in their design and were able to shorten the lengths of the shafts which gave the Joint Venture a competitive advantage at bid time. Drilled shafts were constructed using the Oscillator/Rotator method by placing casing in advance of the excavation to shaft tip, then extracting during concrete placement.

One of the bent lines of shafts had several utilities that were of concern. A Chevron line was within 4 foot 10 inches, a water line 3 foot 10 inches, and a high pressured hydrogen line within 2 foot 10 inches. Our crews exercised extreme caution to ensure that the utilities were not compromised and the low vibration of the oscillator method added another level of precaution thus eliminating damage to the utilities.

GROUND CONDITIONS

Shallow soils are very soft clays and silts, and were underlain at a depth of about 40ft by an old willow mat that had been placed as an erosion protection measure durig the original bridge construction. Beneath the surficial soils to below the tip of the drilled shafts at elevation - 195ft are loose to dense alluvial sand with occasional layers of soft clay.

QUALITY CONTROL

The shaft integrity was tested using SCL testing. Visual inspection by the Mini SID camera ensured the clean and level shaft base. Base grouting using the steel CSL access tubes was performed to enhance shaft performance. The concrete mix had the characteristics of self-consolidating concrete with 35% of the Portland cement replaced by granulated blast furnace slag.

This job was managed by our Northwest Division located in Kent, Washington.

Click HERE for a printable copy of this project (PDF format).