Photo Credit: Missouri Department of Transportation
I and my fellow bloggers here at DBA (David Graham and Aaron Hudson) try to keep up with the various projects under construction that we had a part of. Sometimes it is hard to do once we have left the site after foundations are complete. Modern information technology makes it much easier, especially since most large infrastructure projects have a significant public outreach effort, either by the project design/build team, or the owning agency.
This is the second report from their research project on rock-socketed drilled shafts in the Southeast U.S. This report is from the Lawrenceville, Georgia test site where shafts constructed in metamorphic rock of the Piedmont geologic province were load tested using the O-Cell load test device. The report link is below. Additional information about the test site can be found at the Lawrenceville Site Page.
The first site of this project was in Nashville, Tennessee where shafts constructed in limestone were tested. Information on the Nashville Site and the test reports can be found at the Nashville Site Page.
Both reports will be the feature of a paper and presentation by Robert at the 2012 ADSC Expo, March 13-17, in San Antonio, TX. More information about the Expo can be found here.
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.
1 – Unit Base Resistance
(Building and Earth Sciences, Inc.)
1 – Unit Side Resistance
Todd Barber (Geo-Hydro Engineers, Inc.)
2 – Unit Base Resistance
Todd Barber (Geo-Hydro Engineers, Inc.)
2 – Unit Side Resistance
Jim Pegues (Southern Company Svcs.)
Tom Scruggs (Georgia DOT)
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.
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.
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 Share Registrars 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 18th or 25th). The actual load testing would probably take place the week of August 8th, 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.
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 email@example.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.
A technical note by Tim that appeared in the December 2010 issue of the DFI Journal has been added to our publications page. Tim’s note examines some issues related to axial load testing of augered cast-in-place (ACIP) piles, also know as augercast piles or CFA piles, that are not covered in ASTM D 1143/D 1143M-07 Standard Test Methods for Deep Foundations Under Static Axial Compression. Specifically, load hold time, unload-reload cycles, and fluctuations in incremental load are discussed as they relate to load testing for determining axial capacity or axial load distribution of ACIP piles. Details of instrumented ACIP pile load testing are also covered.
DFI requests that the following be included with all DFI papers we post:
“This paper was originally published in DFI’s bi-annual journal, Volume 4, No. 2 in December 2010. DFI is an international technical association of firms and individuals involved in the deep foundations and related industry. The DFI Journal is a member publication. To join DFI and receive the journal, go to www.dfi.org for further information. ”
Good morning DBA fans! I’m here to give you the latest news on the Hastings Bridge project.
The weather has been a bit chilly in Hastings, MN but that isn’t stopping progress. Paul provided the update below and this picture of one of the beautiful mornings on the site.
Installation of the 12.75” diameter open-ended pipe piles for the column-supported embankment (CSE) is well under way. Each pile is around 165’ in length and will support a geogrid-reinforced load transfer platform (LTP). Light weight fill, or geofoam, will be used to transition from the CSE into the existing embankment.
Installation of the North Embankment retaining wall piles has begun and is about 50% complete.
The Pier 10 test pile was installed and tested with AFT’s 30MN axial Statnamic device. The pile is a 42” open-ended pipe pile with 7/8” wall and is embedded about 190’. Check out the video below. The Pier 6 test pile has also been installed and tested axially and laterally with a Statnamic device.
That’s all for now, but come back later for additional updates on this exciting project. Thanks for reading!
Dan recently played the part of storyteller at the Southeastern Transportation Geotechnical Engineering Conference (STGEC) 2010 conference in Charleston, West Virginia when he gave the lunch presentation on the conference’s first day. He took the audience on a trip down the Mississippi River from a foundation engineer’s perspective, talking about several bridges that DBA has had the pleasure to work on, or is still working on, along the river the last few years. Dan began with the I-35W Bridge replacement in Minneapolis, Minnesota and ended at the Huey P. Long Bridge in New Orleans, Louisiana. Stops along the way included the Hastings Bridge (Hastings Minnesota), the new I-70 Bridge (St. Louis, Missouri), and the Audubon Bridge (New Roads/St. Francisville, Louisiana). Dan covered some of the technical issues/problems associated with each project and the solutions applied to complete the foundations (or complete the design). It was a very informative talk presented in a unique way that everyone at the luncheon seemed to enjoy. Dan’s presentation is now available on our Presentations Page.
Immediately after lunch, Robert made a presentation that described some of the pile load tests performed on two of the storm protection projects in New Orleans that DBA was privileged to be involved with through Kiewit. By following Dan, it provided a little continuity to the story as Robert took the group below the Huey P. Long Bridge to the levees and canals downstream of New Orleans. Robert’s presentation can also be found on our Presentations Page.