Dr. Steve Dapp…in Taiwan!

By Robert Thompson, on October 11th, 2011

During a recent trip to Taiwan, Steve had the opportunity to participate in a lecture on base grouted drilled shaft foundations. He was invited to speak at a meeting of the Chinese Taipei Geotechnical Society (CTGS), also known as the Taiwan Geotechnical Society (TGS), by Dr. Prof. San-Shyan, Lin, National Taiwan Ocean University (current president of TGS). The meeting was held at the National Taiwan University of Science and Technology.

His visit on 21 June 2011 was noted in the August 2011 issue (Volume 5, No. 4, p82) of the ISSMGE Bulletin. During his lecture, Steve talked about the experiences of DBA with base grouting drilled shafts at the Audubon Bridge and the Huey P. Long Bridge on the Mississippi River in Louisiana. Steve said that base grouting has become a very common technology in Taiwan for high rise structures supported on drilled shafts.

The meeting is noted here on the TGS site.

(Source: ISSMGE Bulletin Volume 5, No. 4, p82)

ADSC Lawrenceville Test Site–We Have Winners!

By Robert Thompson, on October 6th, 2011

That’s right load test fans, The results are in! The ADSC Southeast Chapter is proud to announce the “winners” from the prediction contest for the Lawrenceville, GA test site. In the table below, we have listed the winner and their prediction. The winners are the closest to the average measured values as reported by Loadtest, Inc and may not represent the reported maximum values recommended in the final report by DBA. We won’t release the final report until the ASCE Georgia Section Geotechnical Group meeting November 15, 2011 at 6:30pm at the Georgia Power Company’s Headquarters in Atlanta. Dr. Brown will be presenting the findings then – so come to the meeting and get it first, or look to the DBA or ADSC web sites after November 15th to get the report.

Shaft	Name	Prediction
1 – Unit Base Resistance	Gloria Rodgers (Building and Earth Sciences, Inc.)	750 ksf
1 – Unit Side Resistance	Todd Barber (Geo-Hydro Engineers, Inc.)	50 ksf
2 – Unit Base Resistance	Todd Barber (Geo-Hydro Engineers, Inc.)	690 ksf
2 – Unit Side Resistance	TIE: Jim Pegues (Southern Company Svcs.) Tom Scruggs (Georgia DOT)	3 ksf

Audubon Bridge–Cofferdam Construction Article

By Robert Thompson, on July 31st, 2011

As noted earlier on this blog, the Audubon Bridge opened a little bit earlier than planned. Although over a year old, an article recently came to my attention that puts a spotlight on the unique engineering and construction that went into the cofferdams for the two main bridge piers in the Mississippi River. The article is “John James Audubon Bridge Project – Cofferdam Construction for the Main Span Pier Foundations”, published in the February 2010 issue of Louisiana Civil Engineer, the Journal of the Louisiana Section of the American Society of Civil Engineers.

The article’s lead author, Sereno Brown, P.E., was the construction team’s Project Engineer for the design-build project. In the article, Mr. Brown outlines the issues that led to the team selecting a pre-cast concrete cofferdam over other methods, the design methodology, and then the construction of the cofferdam. The effort posed several significant design and construction challenges, including the sequence of lowering the cofferdam into place through a set of hydraulic jacks. The entire process was truly an amazing engineering and construction feat.

Download the article here.

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.

Drilled Shaft Article by Dan in Geo-Strata

By David Graham, on July 22nd, 2011

Constructability Considerations When Designing Drilled Shaft Foundations for Bridges

The May/June 2011 issue of ASCE’s Geo-Strata focuses on bridge geotechnics. Dan contributed an article to this issue summarizing key constructability considerations for bridge drilled shaft designers. Specifically, the article focuses on fresh concrete properties and reinforcement design. Discussion of self consolidating concrete (SCC) and column-shaft connections is also included. The article has been added to our publications page and is available through the link above. Additional details related to bridge drilled shaft constructability can be found in the 2010 FHWA Drilled Shaft Manual here.

Audubon Bridge Opened To Traffic (earlier than planned!)

By Robert Thompson, on July 20th, 2011

The John James Audubon Bridge was opened to traffic on May 10, 2011 a little earlier than planned. While the project is not 100% complete, the bridge was sufficiently complete to allow an emergency opening due to closure of the nearby ferry the bridge is replacing. From the project website:

Due to the high level of the Mississippi River causing the closure of the New Roads/St. Francisville ferry, the Louisiana Department of Transportation and Development (DOTD) opened the John James Audubon Bridge at 10 a.m. on Thursday, May 5, 2011. This emergency opening allowed continuous river-crossing access for traffic affected by the ferry closure. The ferry, which carried approximately 720 vehicles per day according to 2009-2010 DOTD statistics, is permanently closed with the opening of the Audubon Bridge.

Construction is still ongoing and could affect traffic until the project is 100% complete later this year.

ADSC Load Test Research – Lawrenceville, GA Site – SCHEDULE UPDATE

By Robert Thompson, on June 27th, 2011

The planned second load test in the ADSC research project for rock sockets in the Southeastern U.S. is moving closer to execution. Bruce Long of Long Foundation Drilling Company provides this update:

To Fellow Load Testers,

We want to thank everyone who submitted questions or comments regarding the preliminary load test program submitted to us by Dr. Dan Brown. Those comments, and more, will be considered while fine-tuning the program.

Because we have several companies donating their time and money, we have to be flexible with respect to the installation and testing dates. We have tentatively selected some dates, but these are subject to change depending upon the workloads of those volunteering their efforts. We hope to begin shaft installation during the last two weeks of July (weeks beginning the 18^th or 25^th). The actual load testing would probably take place the week of August 8^th, with the actual test date being decided upon by sometime in early July (I hope to give everyone at least a 3-4 week notice).

The actual test date would include a field day visit by all interested parties to the test site at Foundation Technologies office in Lawrenceville, GA. Activities will include a load testing discussion led by Dr. Dan Brown, along with lunch. We would then move to the test site where Loadtest, Inc. will be conducting the Osterberg Load Test on our first shaft. A discussion of the testing process and procedures by Loadtest will precede the actual testing (We will be submitting information later regarding a load test contest where each of you will get to predict the outcome of the test with a special prize going to the winner). We also hope to be drilling on the second shaft that day and will be discussing the drill rigs, tools, and other equipment being used, as well as having the other Osterberg cell available for viewing. This site visit proved to be very well received when we did it in Nashville at the last load test. We hope for a big turnout that day.

I wanted to give everybody a brief update and will be in touch when additional information becomes available in the near future. Thank you for your interest, and if anyone has any questions regarding this plan, please feel free to call me at your convenience.

Bruce Long

President

Long Foundation Drilling Co.

Previous post is here.

The test site page is here.

The main page for the research project is here.

ADSC Rock-Socketed Drilled Shafts in the SE Research Project Site No.2 – Comments Welcomed

By Robert Thompson, on May 9th, 2011

After some lengthy delays, the rock-socketed drilled shaft research sponsored by the Southeast Chapter of the ADSC is back on track. A second site has been selected at the site of Foundation Technologies, Inc. in Lawrenceville, Georgia. This site will investigate the resistance of some of the rocks of the Piedmont for drilled shaft design. The first test site was in Nashville, Tennessee. The report of the first test site and other information can be found at the test site page. General information about the complete project, including a list of participating/contributing companies and organizations, can be found at the project page.

Bruce Long (Long Foundation Drilling Company) is the lead for the ADSC on this project and has requested interested parties to provide comment on the test plan for the second site (see links below). The hope is to have load testing occur this July if every thing comes together properly. Bruce sent the following email with some refresher material on the Nashville test site and an update on the startup for the Lawrenceville site:

First, I would like for everyone to know that the load test program jointly planned between the Atlanta area ASCE Geotechnical community and the Southeast Chapter of the ADSC is alive and well despite some longer than planned delays. The final boring data has been in hand for some time and Dan Brown and his group have reviewed this information and submitted a preliminary load test program for review and comment. This program is very similar to the test program that was performed in Nashville a couple of years back. For informational purposes, the results of that test program has resulted in an increased awareness of the available load carrying capacity in the limestone formations in the area. Historically, shafts were designed almost exclusively utilizing end bearing with the normal range of values allowed ranging from 60-100 KSF. In recent months, we have seen projects now being designed with recommended values ranging from 100 up to 250 KSF with an increasing number of designs also relying on skin friction values up to 25 KSF in sound limestone sockets. The information gained from these load tests has given area engineers increased confidence in raising the bar for future drilled shaft designs. This will result in lower foundation costs for owners of public and private projects alike. For those involved in the design process, better information will result in improved design values and an improved competitive position for those willing to utilize this data.

Now we are prepared to move forward with the planned testing in the Atlanta area. I have attached the final geotechnical report for your review. There are several people and companies that have generously volunteered their time and expertise to make this happen, Todd Barber with Geo-Hydro Engineers, Inc. being the most notable of these. His persistence and assistance was invaluable. Others that contributed in a variety of ways include Mactec, Golder Associates, Georgia Tech and GeoTesting Express. Thanks to everyone for their efforts.

Also attached is the preliminary memo from Rob Thompson of Dan Brown and Associates. What he has outlined are suggestions based upon the boring information for two separate Osterberg Load cell tests. One would be on a shaft that was hand-cleaned, while the second shaft would be machine-cleaned only. This would allow a comparison to determine the effects (if any) that traditional hand-cleaning has on shaft behavior. This memo is being sent out with the intention that review and comments from the geotechnical community be considered and incorporated in the final program. Depending upon the extent of comments, a final meeting could be necessary to discuss any proposed revisions. If suggestions are minimal, such a meeting might not be required. In this case, we would proceed with shaft installation and testing as soon as possible.

Thanks for your patience–I think that the final results will be worth the time. It has been very rare that full scale load testing be done in hard rock areas (Piedmont or Limestone), but if the results of our Nashville area testing are any indication, I think the results will definitely show that the effort was worthwhile.

Please take time to review this information and e-mail or call me with any comments that you might have. As soon as all comments have been reviewed, we will let everyone know our plan to proceed. I would like to have comments submitted to me by May 27, 2011. If there are any questions regarding our plans, schedule, etc., please feel free to contact me at your convenience.

I have linked the proposed load test plan memo and the boring information below. Bruce would like comments from interested parties to be submitted by May 27, 2011. Please submit comments to him at blong@lfdc.com.

A blog page for this test site has been created and will be updated as the project progresses. We intend to have a prediction contest similar to the one we had for the Nashville site, so keep checking for information. Better yet, subscribe to our blog using one of the social media links at the top of the right sidebar of the blog.

Load Test Plan Memo from Dan Brown (20 May 2010)

Summary of Test Borings from GeoHydro Engineers (26 Jan 2010)

Hastings Update and Photo Album

By David Graham, on April 1st, 2011

Well, I, David, have survived my first (and hopefully last) winter in Minnesota. I spent most of January and February observing the installation of the Pier 5 drilled shafts at the new Hastings bridge project in Hastings, Minnesota. In addition to the drilled shafts, there has been a lot activity at Hastings since Aaron last blogged about this project in January. A link to his post is here. All of the ground improvement piles for the column-supported embankment have been installed and approximately 75% of the caps have been poured. The 42-inch piles and pile caps for Piers 8, 9, and 10 are also complete. Piles for the north embankment retaining wall have been installed and construction of the wall has begun. Excavation for the rock bearing spread footings that will support the south land piers is in progress. Work at Piers 6 and 7 and on the north shore are currently on hold as the Mississippi River is experiencing its annual spring flood. The water level is about 14 feet above normal elevation.

I have taken the pictures Paul and I have collected over the last few months and uploaded some of the more interesting ones to a Picasa web album. The pictures are generally in chronological order and cover most of the construction process from November of 2010 right up to the end of March 2011. A link to our our video of a Statnamic load test at Hastings that Aaron blogged about is here.

Audubon Bridge Closure–The Span is Complete!

By Robert Thompson, on February 1st, 2011

On December 29, 2010, Audubon Bridge Constructors recently “closed” the main span of the John James Audubon Bridge between New Roads and St. Francisville, Louisiana. Watch the video featured at the top of the page at the bridge link to hear about the bridge, including the drilled shaft foundations! For something really fascinating, go to the webcams here and scroll back through the various dates. They have archived images all the way back to start of construction.

Photo: Chris Usery, Figg Bridge Inspectors

The last cables were installed on January 3, 2011 as noted on the project website:

The last two cable stays of the longest cable-stayed bridge in the Western Hemisphere were installed on January 3, 2011, five days after the spans were connected. The John James Audubon Bridge, Louisiana’s newest crossing over the Mississippi River, now has all of its 136 cable stays in place.

This bridge will be the longest cable-stayed bridge in North America when it opens later in 2011. Again, from the project web site:

The spans of the longest cable-stayed bridge in the Western Hemisphere were connected on December 29, 2010, stretching 1/3 of a mile over the Mississippi River. The John James Audubon Bridge, connecting Pointe Coupee and West Feliciana parishes in Louisiana, is approximately 92% complete. Construction of the spans began from both sides of the 500-foot tall towers earlier this year. Both sides continue to progress at a rapid pace, and now the meeting of the spans has occurred.

Steve Dapp and I had the pleasure of working with many great people during our time on site (much more time for Steve than for me!) during foundation construction. One of them, Chris Ursery of Figg Bridge Inspectors, has been great about providing us with photos now and then to keep us updated of some of the details of the bridge construction. Chris has granted us permission to share a few of his recent photos, which are shown below or can be seen in our web albums here.

Previous post on Audubon Bridge.