In the forward of the report, Andrew Lemer of TRB writes:
NCHRP Report 697: Design Guidelines for Increasing the Lateral Resistance of Highway- Bridge Pile Foundations by Improving Weak Soils presents design guidance for strengthening of soils to resist lateral forces on bridge pile foundations. Lateral loads may be produced by wave action, wind, seismic events, ship impact, or traffic. Strengthening of soil surrounding the upper portions of piles and pile groups—for example by compaction, replacement of native soil with granular material, or mixing of cement with soil—may be more cost-effective than driving additional piles and extending pile caps as ways to increase the bridge foundation’s capacity to resist lateral forces associated with these loads. This report presents computational methods for assessing soil-strengthening options using finite-element analysis of single piles and pile groups and a simplified approach employing commercially available software. The analysis methodology and design guidelines will be helpful to designers responsible for bridge foundations likely to be exposed to significant lateral loads.
(Note from Robert: I used material from the team proposal and the article referenced below for this post, with the authors’ permission. Also, DBA is a significant participant in the project and we hope to provide updates as things move along.)
The Federal Highway Administration (FHWA) has partnered with the ADSC: The International Association of Foundation Drilling (ADSC-IAFD) on a comprehensive research project on post-grouted (also called base grouted or tip grouted) drilled shafts. The FHWA and the deep foundations industry are very interested in the proper application and implementation of post-grouting for drilled shafts. The potential benefits of post-grouting have been demonstrated, and the industry has attempted to capitalize on these benefits in numerous ways. Some of these attempts have been successful while others have not, which has led to confusion and even misapplication of post-grouting technology within the industry.
The project will include an extensive synthesis of existing practice and literature, evaluation of theoretical concepts, full-scale field testing, and comprehensive analysis of the field testing to develop design methods. Each phase of work will have a set of deliverables that will go through a rigorous review process. The project is anticipated to be completed sometime in 2014.
The four main objectives of the research program are:
Bound the application of the post-grouting technology for the current state-of-knowledge;
Quantify the improvement mechanism(s) for the post-grouting of drilled shafts;
Develop design methodology(ies) for appropriate applications of post-grouting; and,
Provide method(s) for verification.
To accomplish these objectives, a highly qualified and experienced team of practitioners and researchers has been assembled to execute this project. This team includes industry representatives from construction, design, and academia that can bring a variety of perspectives to the project as well as respond to input from the many stakeholders within the geotechnical and transportation design and construction communities that routinely implement this technology.
Dr. Antonio Marinucci, MBA, P.E., of ADSC-IAFD will serve as Project Manager for the project and will be responsible for coordination and oversight of all project activities. Dr. J. Erik Loehr, PE, of the University of Missouri will serve as Principal Investigator (PI) with overall technical responsibility for the project including technical planning, data collection, synthesis, interpretation, and document production. Three Co-Principal Investigators (Co-PIs) will collaborate with Dr. Loehr to address the technical aspects of the project: Dr. Marinucci of ADSC-IAFD; Dr. Dan Brown, P.E., D.GE of Dan Brown and Associates, PC; and Dr. Jesús Gómez, P.E., D.GE of Schnabel Engineering Consultants, Inc.
An Advisory Panel will be utilized to provide additional objective technical insight regarding planning and execution of the project and development of the project deliverables, as well as unique expertise regarding specific aspects of the proposed work. The Advisory Panel will include:
Mr. Tom Armour, P.E., D.GE of DBM Contractors, Inc.
Dr. Donald Bruce, CEng, D.GE of Geosystems, LP
Mr. Allen Cadden, P.E., D.GE of Schnabel Engineering Consultants, Inc.
Dr. Steven Dapp, P.E. of Dan Brown and Associates, PC
Mr. Michael Muchard of Applied Foundation Testing
Dr. Miguel Pando, PEng of the University of North Carolina at Charlotte.
To provide objective review and evaluation of project plans and deliverables at key stages of the project, a formal Peer Review Panel will be formed composed of representatives from throughout the drilled shaft industry. The peer review process will be coordinated through the drilled shaft technical committees of each of the major stakeholder organizations in the U.S.: the ADSC-IAFD Drilled Shaft Committee; the ASCE/Geo-Institute (ASCE/GI) Deep Foundations Committee; the Deep Foundations Institute (DFI) Drilled Shaft Committee; and the Transportation Research Board (TRB) Committee on Foundations of Bridges and Other Structures.
The final component of the project team will be the ADSC-IAFD Contractor Members, Associate Members, and Technical Affiliates that will provide substantial in-kind contributions to meet the needs of the proposed experimental programs. Likely in-kind contributions from ADSC members will include provision of testing sites and facilities, construction equipment, materials, testing apparatus, as well as services necessary to complete the proposed project.
The configuration of this team consisting of the PIs, the Advisory Panel and the Peer Review Panel will provide a thorough review process as well as “checks-and-balances” against any perceived or realized personal biases regarding the use of post-grouting with drilled shafts. It is believed that the recommendations resulting from this effort will reflect a consensus on the application, design and construction of base-grouted drilled shafts that will be accepted by the industry at-large. This should result in consistent application of this technique by the industry.
For a detailed description of the project, see the article linked below from May 2012 issue of Foundation Drilling magazine, available from the ADSC-IAFD. In the article, Dr. Marinucci provides the first in a series of updates that will be published reporting the progress of the research through the various phases of the project. We’ll provide posts here as new reports are released, as well as posts of all the action when field work gets started!
While at the 2012 Geo-Congress I purchased a couple of books at the ASCE bookstore. One was GSP 88: Analysis, Design, Construction and Testing of Deep Foundations, Proceedings of the OTRC ‘99 Conference. There are several interesting papers in the GSP, including an early paper by Dan on lateral Statnamic testing. A full scale lateral load test was performed on a 36 inch tests shaft using a Statnamic device. The test was performed at the Auburn University National Geotechnical Experiment Station Site (NGES). I guess you could say this paper is literally a “blast” from the past!
The paper describes a program of lateral load tests on six drilled shafts installed in a loess deposit at a site in Wyandotte County, Kansas. The lateral load test data, along with site characterization data that included CPT data, were used to develop a hyperbolic model to generate p-y curves for use in lateral load analyses in cemented soils. The model should be applicable to many “c-phi” soils (soils with both a cohesion intercept and a friction angle, such as cemented soils). Degradation of the static soil model to account for cyclic loading effects is included in the new model.
This paper was originally published in the DFI Journal,Vol. 5 No. 2, December 2011, the bi-annual Journal of the Deep Foundations Institute. DFI is an international technical association of firms and individuals involved in the deep foundations and related industry. The DFI Journal is provided to DFI members at no cost electronically or can be purchased in print at www.dfi.org.
This paper is one of several papers and articles published form a series of research projects by KU and the Kansas DOT. Some of the previous work can be found at these links:
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)
The Deep Foundations Institute is pleased to announce Dan Brown, P.E., Ph.D., as the recipient of the DFI 2011 Distinguished Service Award. The award, in its 31st year, honors individuals chosen by their peers for exceptional contributions to DFI and to the industry.
Brown began his career with a B.S. from Georgia Tech, and later received his Ph.D. at the University of Texas, Austin, in only 28 months, while working. He then taught at Auburn University for 22 years before setting up his own consulting firm in Tennessee. The Winter 2011 issue of the DFI magazine included a profile of Brown that chronicled the universal admiration and regard for him within the industry. He was cited by others for his expertise, his intelligence and ability to teach others. Brown and his firm are sought out for advice everywhere.
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.
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.