ADSC Lawrenceville Test Site–Prediction Contest!

By Robert Thompson, on July 26th, 2011

Update (7/31/11) – Field Day set for Thursday, August 18th – More info here!

Back by popular demand, we will hold a prediction contest for the second test site in the ADSC drilled shaft research project for rock sockets in the Southeastern U.S. Contestants are encouraged to download the information linked below and then submit their predictions of unit side resistance and base resistance that will be measured by the O-cell tests. The winner will be announced at the field test and demonstration day on site, as well as published in this blog along with all submitted predictions.

Two test shafts will be installed July 26 – 29th at the yard of Foundation Technologies, Inc. One will include a rock socket to attempt to test side and base resistance in the rock socket. The other shaft will be drilled to “rock auger refusal” to attempt to test side resistance in the partially weathered rock (locally termed PWR) and base resistance at “rock auger refusal”. In the Piedmont area, the highly weathered upper rock zone is commonly called PWR. Another common usage is “rock auger refusal” to define where “hard rock” begins. It is thought that designers may be overly conservative with base resistance values at “rock auger refusal”. Hopefully this test will provide useful data in that regard.

Testing will occur during a field demonstration day in mid-August. We’ll post the date once it is finalized.

Information to include the test shaft configurations and exploratory boring data can be downloaded here.

The contest entry form along with instructions for submission can be downloaded here.

We will have Aaron on site to observe and take lots of pictures. We’ll post his photos of the excavations as soon as we can (check the project web page soon after August 1st) to assist in making predictions.

All predictions must be submitted by the close of business, August 12, 2011.

For more information, visit the test site page.

Previous posts.

New I-70 Bridge Featured in Foundation Drilling Magazine

By David Graham, on December 10th, 2010

The new I-70 bridge over the Mississippi River near St. Louis, Missouri is quite the project. When completed, it will be the third longest cable-stayed bridge in the United States, with a 1,500-ft main span. Most significantly for the geotechnical community, the bridge made history when one of its 11-ft diameter drilled shafts resisted a world record breaking 36,000 tons (bi-directional) during an O-cell load test. The bridge has already seen press in Civil Engineering Magazine (July 2010, page 30-32), at ENR.com, and in a post by Robert on this blog. Now, an article by DBA’s Paul Axtell is featured in the September/October issue of Foundation Drilling Magazine. The editor summarized the article saying:

The information in the following article is a composite of material that came to Foundation Drilling Magazine from three separate sources. Part I is based on information gleaned from an article that was published on the Associated Press news wire. Part II is excerpted from ENR’s August 18th, E-Newsletter. Part III was provided by Paul Axtell and Dan Brown of ADSC Technical Affiliate company, Dan Brown and Associates. The bridge project is of interest in general. The Osterberg Load Cell test will be of particular interest to professionals in the deep foundation industry, and specifically for those who work in the drilled shaft segment.

Axtell, P.J. (2010). “Mississippi River Bridge Project Includes Record Load Test: A Three Part Story”, Foundation Drilling, Vol. 31, No. 7 September/October 2010.

Three Updates: World Record O-Cell Load Test in St. Louis, MO

By Robert Thompson, on August 18th, 2010

Check out the bottom of my post on June 30th World Record O-Cell Load Test for some updates and new links to recent news articles.

World Record O-Cell Load Test in St. Louis, MO!

By Robert Thompson, on June 30th, 2010

DBA was part of foundation engineering and construction history while participating in a drilled shaft load test for the New I-70 Mississippi River Bridge in St. Louis, Missouri. A new O-cell world record of 36,000 tons (bi-directional) was achieved on the test, besting the former record of just under 32,000 tons set in 2005 in Korea (see here).

The test shaft was built by MTA (a joint venture of Massman/Traylor Brothers/Alberici Constructors) as part of an Alternative Technical Concept (ATC) that MTA submitted in their winning bid. During the bid phase, the owner allowed ATC’s to be submitted by pre-qualified teams. These ATC’s were unique to the team that submitted them (e.g., each team was allowed to submit their own ATC’s if they desired, but the ATC’s were not shared amongst all the teams). DBA worked with MTA to develop an ATC that optimized the drilled shaft foundations shown in the “baseline” drawings provided by the owner. That ATC provided a more economical foundation solution that was accepted, bid, and awarded (note MTA also had the option of bidding the “baseline” drawings as-is). A full-scale load test on a dedicated test shaft using the Osterberg Cell (O-cell) test method was included in the ATC to: 1) prove the design values used for the resistance in the rock socket; and (2) take advantage of higher resistance factors for using a load tests as opposed to only calculations. The baseline drawings did not include a load test.

Loadtest, Inc. performed the load test. The bottom-up static load test applied slightly greater than 36,000 tons (bi-directional) to the shaft resulting in about 1/8in of upward movement of the shaft and about the same magnitude of downward displacement at the base. The rock socket was about 23ft deep and 11ft in diameter in very hard limestone. Four 34in O-cells placed at the base of the shaft were loaded to 150% of their rated capacity to achieve the record load.

UPDATE (8/4/10): The bridge was featured in the July 2010 issue of Civil Engineering magazine from ASCE in the “News” section. Follow the link below and then go to Page 30.

Civil Engineering July 2010

UPDATE (8/17/10): Press Release from MTA (contractor joint venture).

UPDATE (8/18/10): ENR.com Article