The drilled shaft foundations for the new I-70 Mississippi River Bridge in St. Louis, MO are the subject of two recent papers written by Paul and Dan and published by DFI. Dan presented the paper focusing on the Alternate Technical Concept (ATC) process at the DFI 36th Annual Conference in October. (previous post here). A case history paper by Paul and Dan was published last month in Volume 5, Number 2 of the DFI Journal. Links to the papers are below, as well as on our Publications page. Other posts on this bridge are here.
This paper was originally published in the Proceedings of the 36th Annual Conference on Deep Foundations, the 2011 annual meeting of DFI. Go to www.dfi.org to purchase the procedings or for further information.
This paper was originally published in DFI’s bi-annual journal, Volume 5, No. 2 in December 2011. 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.
DFI held its 36th Annual Meeting October 18-21 in Boston, including the annual awards banquet. Dan was honored with the 2011 Distinguished Service Award at the banquet. The Christopher S. Bond Bridge in Kansas City, MO was honored with a Special Recognition award (one of 5 runners-up for the Outstanding Project Award). Photos of DBA folks at the event are posted below. All of the photos from the meeting can be found at this link.
Dan gave a presentation on the Alternate Technical Concept (ATC) that DBA supported for the I-70 Bridge over the Mississippi River in St. Louis, MO. The link to the presentation is below. (Some previous posts here and here and here; posts with links to other presentations here).
As massive concrete piers rise from the Mississippi river in southeast Minnesota, people have begun to take notice of what will become the longest free-standing tied-arch bridge in North America. A unique project in several respects, the new Hasting bridge has recently been featured in articles on the websites of ENR and Roads & Bridges. The ENR article is a republication of an article that originally appeared in the Minneapolis Star Tribune highlighting the construction process of the last year, with particular focus on the process of constructing the river piers. The Roads & Bridges article is a more technically in-depth piece written by the lead bridge engineer Vincent T. Gastoni, P.E., of Parsons Transportation Group. Both articles discuss some of the many geotechnical changes faced on this project. This excerpt from Roads & Bridges is a concise description of the pier foundations and some of the reasoning behind their selection:
The main river piers are concrete delta-style frames with the tied-arch superstructure fully framed into the pier through the knuckle connection. The stiffness of the foundation system was then integral to the overall force effects in the structure. The north pier is located in 190 ft of soft soils overlaying rock and supported on unfilled 42-in. driven steel pipe piles. Drilled shafts were investigated early but were not cost-effective, impacted the schedule and presented a risk to the existing bridge due to potential caving effects. Statnamic pile load testing was used to validate the vertical capacity and lateral performance of the 42-in. piles. The south pier footing is close to the rock surface; however, the rock was deeper, more sloped than expected, and the originally planned spread footing was changed to short drilled shafts during the final design. Dan Brown & Associates provided the team with geotechnical analysis and recommendations.
Our Tim Siegel pointed out that the statement “It’s a marvel of engineering that requires ingenious construction techniques, most of which are invisible to the drivers whizzing by overhead,” from the Star Tribune, is an accurate description of how our work as foundation designers and constructors is often viewed. Although much of the ingenuity and innovation that goes into the geotechnical aspects of projects often goes unnoticed by the general public, it is certainly refreshing to see articles like these. For us at DBA, it is even more refreshing to see our efforts credited by name as they were in the article by Vince when he wrote, “Dan Brown & Associates provided the team with geotechnical analysis and recommendations.”
For a design-build project with so many different geotechnical components (driven piles, drilled shafts, spread footings, retaining walls, a column-supported embankment, and light weight fill), it is hard to believe that our role as the lead geotechnical engineer is nearing completion just a little over a year after construction began. At this point, the only foundations that have yet to be constructed are some of the rock bearing spread footings at the south approach. DBA will also monitor instrumentation installed in the column-supported embankment for the next two years.
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 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.