A lot has changed from a year ago at the TH 53 Bridge sight near Virginia, Minnesota. This time last year, the design-phase test pile program was wrapping up with three Statnamic load tests and we had just completed our initial geologic field investigation. Since then, significant excavation, rockfall protection, and foundation work has been completed. During summer and fall of 2015, DBA worked closely with contractors Hoover Construction and Pacific Blasting to maintain rockfall protection throughout the East Abutment and Pier 1 (East Pier) excavation process. Official ground breaking occurred last November and foundation work started shortly after. A total of 32, 30-in micropile foundations have been installed by Veit Specialty Contracting and Kiewet Infrastructure has completed a temporary causeway across the massive Rouchleau Pit by placing over 300,000 cubic yards of fill.
With the foundations of both piers complete, and the pier towers are starting to rise up, where they will carry the bridge deck 200 ft above. The abutments are also taking shape with rock bearing concrete footings now poured on both sides of the pit. The only foundation work left is to install tieback anchors at the East Abutment, which will reduce the lateral loading of the tall piers.
In a little over a year, the bridge is scheduled to open to traffic. You can keep track of the progress through the project web cam.
TH 53 Bridge, artistic rendering courtesy of MnDOT
The official groundbreaking for the Trunk Highway (TH) 53 Bridge and Relocation Project occurred last week at the project site in Virginia, Minnesota. The bridge, which is the main element of the project, will span the Rouchleau Iron Ore Mine Pit. The project is scheduled to be completed in a brisk two years in order to allow for mining where a section of TH 53 is currently located. Upon completion the 1,100-foot long bridge will be Minnesota’s highest, with the roadway sitting approximately 330 feet above the bottom of the floor of the Rouchleau Pit. Kiewit was selected as the general contractor for the project with Veit Specialty Contracting as the foundation contractor.
Foundation construction will start in late November or early December with the installation of 30-inch diameter micropile foundations for the western pier of the three span, steel plate girder bridge. Although the foundation work is just about to get started, DBA has been hard at work on the project for over a year. DBA first got involved as a consultant to MnDOT for the design-phase load test program conducted last fall. Since then, DBA was contracted as the geotechnical engineer of record for the project. Working with bridge designer Parsons, DBA designed the bridge foundations, an anchored abutment, and rockfall hazard mitigation systems for this geologically challenging site. DBA has also analyzed several soil and rock slopes to verify stability of the bridge and roadway.
Most recently, some of us were on site to inspect some of the rockfall protection elements on the east side of the mine pit. Last week we spent two days climbing and repelling a on a portion of the eastern highwall, which is currently covered in rockfall protection drapery. The drapery was installed for the protection of workers excavating rock for the eastern bridge pier. The drapery was installed by Pacific Blasting in association with Hoover Construction. Some pictures from our drapery inspection visit are below.
For more information about the project, click here, and for our previous blog posts on this project, click here.
John and Paul provide some scale to this picture as they work their way down the drapery.
John concentrating as he inspects the drapery seam as he decends.
Just before Christmas, David, Tim, and Nathan joined Dr. Ronaldo Luna and his graduate student, Devin Dixon, of Missouri University of Science and Technology (formerly the University of Missouri–Rolla) to conduct a live load test on the all but officially complete Foothills Parkway Bridge No. 2., near Pigeon Forge, Tennessee. During installation of the micropile foundations, DBA and Dr. Luna’s research team installed strain gages in four micropiles and at the base of the pier pedestals at both Piers 1 and 2 of the bridge. Strain data have been collected during construction of the superstructure. Following completion of the bridge, the live load test involved loading the bridge with four loaded dump trucks at prescribed locations with respect to the instrumented piers. Data were collected for several load configurations. The aim of the research is to better understand the performance of micropiles and micropile groups, particularly with respect to bending.
Visiting the site for the load test provided an opportunity to take some great pictures of this particularly scenic bridge nestled in the foothills of the Smoky Mountains. A new web album of pictures taken by David has been added to our Picasa page here, and some aerial photos of the nearly completed bridge taken in December by Aerial Innovations have been added to our Picasa web album Foothills Parkway Bridge No. 2 – From a Bird’s Eye View.
In addition to the ADSC EXPO 2012 earlier in March (see post here), the annual Geo-Institute meeting for 2012, GeoCongress 2012 , was held later in the month in Oakland, California. The conference featured a very large technical program with a variety of tracks covering geotechnical engineering topics. There were also the annual named lectures (Terzaghi, Peck, etc.) and other special events. Randy Post wrote about his time at the GeoCongress at his blog, GeoPrac.net. Check out all of his posts on the conference, including photos and video.
A key feature of this congress was the State of the Art (SOA) and State of the Practice (SOP) Lectures given throughout the four days. Thirty prominent engineers were invited to give the SOA/SOP lectures. Dan gave one of the SOP lectures with his highlighting advances in drilled foundation use and selection. His paper, along with all of the other SOA/SOP lectures, is included in GSP No. 226, Geotechnical Engineering State of the Art and Practice, Keynote Lectures from GeoCongress 2012. His presentation is linked on the image below.
During the regular technical sessions, John Turner presented a paper on a recent project case history on rock-socketed drilled shaft foundations used for a bridge . His paper is in the conference proceedings volume (GSP No. 225):
Dr. Erik Loehr, P.E. was honored by the ADSC with the ADSC Outstanding Service Award, presented at the President’s Luncheon at their 2011 annual meeting in New Orleans, Louisiana (Feb 1 –5, 2011). The award recognized Erik’s research in the use of micropiles for slope stabilization and as foundations. From the March/April 2011 edition of Foundation Drilling:
ADSC’s Outstanding Service Award was garnered by Dr. J. Erik Loehr, University of Missouri, in acknowledgment of his research and educational efforts that advance the technical aspects of the drilled foundation and anchored earth retention industries.
Dr. Loehr is currently on the faculty of the University of Missouri and is a consultant with DBA.