Tag Archives: Drilled Shaft Construction

Instrumentation at US 231 bridge and Slide

(Written by Andy Boeckmann – DBA)

After successful design and construction of the US 231 emergency slide repair in Lacey’s Spring, Alabama, DBA shifted gears to install a state-of-the-art monitoring system for the project. The monitoring system allows DBA and ALDOT to remotely detect any movement of the drilled shafts, changes in groundwater levels, and movement of the slope, itself.

The monitoring system includes ShapeAccelArray (SAAV) devices to measure displacement profiles with depth. SAAVs, which are manufactured by Measurand, consist of a chain of rigid segments, each 1.5-ft long and about 1-inch diameter. DBA installed 27 SAAV devices at US 231. Each of the 24 drilled shafts has one SAAV, which DBA installed in a 1-inch conduit welded to the drilled shaft reinforcement and emerging from the top of the grade beams connecting the shafts. The other three SAAVs are “free-field” SAAVs, installed in the soil between bridge bents. DBA worked with ALDOT’s drill crews to install the free-field SAAVs.

ALODT drill crew installing a free-field SAAV under the Northbound bridge.

 

Completed free-field and foundation instruments at Bent NB4.

 

DBA also worked with the ALDOT drill crews to install vibrating wire piezometer devices at six locations across the site. Each location includes two piezometers, one in the soil and one just below the top of rock. The piezometers were installed using the fully-grouted method. The piezometers measure pore pressure, which DBA uses to interpret groundwater conditions at the site.

 

Datalogger atop a vibrating wire piezometer.

 

All of the instruments are connected wirelessly to two central hubs that collect the data. The hubs are solar powered.  One of the hubs is equipped with a cellular modem that facilitates remote collection of the data.  RST Instruments manufactures the monitoring equipment as well as the vibrating wire piezometers.

Housing for SAAV devices installed in drilled shafts.

 

R-star hub and solar panel mounted to SB Bent 6.

 

Inside of data collection hub.

 

Results of the monitoring program indicate the foundation system is performing as designed. The US 231 structure has passed its first wet season with flying colors. Despite several periods of heavy rain that resulted in localized slope movement, the drilled shafts have shown only very small movement, typically less than 0.05 inch. The movement shown in the shafts indicates they are resisting loading from the slope movement, but with plenty of reserve capacity. The monitoring system has successfully captured realistic results from all instruments, including the drilled shaft and free-field SAAVs and piezometers.

Piezometer data shows strong correlation between rainfall and increases in groundwater levels.
Example of SAAV drilled shaft displacement. Shaft displacements are very small, typically less than the stated accuracy of the SAAV devices.

The monitoring system is more than just bells and whistles: it is an integral part of DBA’s design philosophy for the US 231 project. DBA engineers were able to implement the innovative strategy of drilled shafts through an active landslide because we knew performance of the foundation system would be actively monitored. This strategy represents a modern take on the observational method, which has represented best geotechnical engineering practice since the profession originated. DBA will also use results of the monitoring program to inform future designs, consistent with our commitment to using state of the art to improve the state of practice.

To read more in detail about the design and construction of the bridge foundations, we published an article i nthe April 2021 issue of Foundation Drilling Magazine:

Thompson, W.R. and Dapp, S.D. (2021). “Innovative Landslide Solution”, Foundation Drilling, Vol XLII, No. 3April 2021, pp51-62.

US 231 Emergency Slide Repair – Laceys Spring, Alabama

DBA had the great fortune to be working with the Alabama Department of Transportation (ALDOT) on a very interesting bridge project in Lacey’s Spring, Alabama just south of Huntsville, Alabama.  On February 12 and 13, 2020 a large landslide occurred on SR-53 (US-231) at milepost 301.7 in Morgan County approximately 1.7 miles south of the Laceys Spring Community.  The slide completely severed the 4-lane divided highway which is a major commuting route between Huntsville and several communities south of the city.  Many of the workers at the U.S. Army Redstone Arsenal, NASA Marshall Space Flight Center, and the contractors and vendors that support these two major installations live in the communities impacted by the closure of the highway.  Detours were established on existing state and county roads, but these added 30 to 60 minutes to commute times, depending on time of day.  ALDOT was under significant pressure from the impacted communities to quickly solve the problem and reopen the road.

ALDOT drill rigs performing exploratory drilling (DBA)

 

ALDOT drilling crews were immediately mobilized to the site to begin drilling exploratory borings and install slope inclinometer casings for monitoring slide movements.  The Department of Civil Engineering at Auburn University was engaged to perform geophysical testing in conjunction with an existing research project for ALDOT.  Geotechnical engineering firm TTL also assisted with field investigation efforts. 

DBA and ALDOT immediately began evaluating several alternate concepts for stabilizing the slide and reopening the road during the soil and rock exploratory drilling.  The design team looked at several retaining wall options, a complete rebuild of the roadway, and bridges.  ALDOT selected a solution that removed most of the existing roadway embankments (built in 1947 and 1970) to reduce loading on the slope and then spanning the slide area with bridges built on the existing road alignments, with the bridges designed to withstand future movements of the slope.  Excavation was begun by Reed Contracting before bridge design was complete in order for the rough grading to be done before the bridge contractor mobilized.

The bridges are two-lane structures, one Northbound and one Southbound, each about 947 ft in length.  The superstructure is AASHTO BT-72 concrete girders and a concrete deck.  There are seven spans in each bridge each about 135ft long.  The grading work was begun while the bridge was still being designed to accelerate the schedule and shorten the time the road would be closed.

The foundations for each pier are a pair of 9.5ft diameter, permanently cased drilled shafts with 9ft diameter rock sockets.  The sockets are 14ft long into the limestone and shale bedrock.  The limestone uniaxial compressive strengths range from 10,820 psi to 28,100 psi. 

After much design and analysis in a highly compressed schedule, a bridge contract was let for bid in early May 2020, less than 3 months after the slide occurred.  Brasfield & Gorrie was the successful bidder and awarded a $15 million contract that has incentives for finishing early, and disincentives for finishing late. 

 

ALDOT UAV flight June 16, 2020

ALDOT UAV flight July 07, 2020

ALDOT UAV flight July 23, 2020

ALDOT UAV flight July 28, 2020

ALDOT UAV Flight Aug 08, 2020

ALDOT UAV Flight Sep 2, 2020

ALDOT UAV Flight Sep 15, 2020

 

Excavating first shaft on the site (DBA)

 

A.H. Beck (Beck) was the drilled shaft contractor, drilling each shaft, placing reinforcement, and placing concrete.   The 9.5ft diameter permanent casing is 5/8 inch wall thickness spiral weld 60ksi steel fabricated by Nucor in Birmingham, Alabama.  The shafts are reinforced with a 1.5inch wall thickness, 8ft diameter, 60ksi steel pipe. These pipes were rolled and welded by Favor Steel in Birmingham, Alabama before being trucked to the site.  The steel plate was manufactured by SSAB in Axis, Alabama near Mobile.  So, the structural steel pipes were completely Alabama-made and the steel travel almost the length of the state!

8ft diameter x 1.5in wall steel pipe for shaft reinforcement (DBA)

 

Inner structural pipe (1.5in) and outer casing (5/8in) (DBA)

 

The pair of shafts for each pier is connected by a reinforced concrete grade beam 10ft wide by 7ft high by 46ft long. To connect the shafts to the grade beam, a 14ft long reinforcement cage is placed in each shaft, embedded 8ft into the shaft with 6ft embedded in the grade beam. The cage consists of 28 No.18 Grade 75 bars.

Grade beam at NB Bent 7 with column steel (DBA)

 

Completed shaft with reinforcing cage to embed in grade beam (DBA)

 

The project includes a robust instrumentation plan with ShapeArray inclinometers installed in each shaft and in the slope, supplemented by traditional inclinometers in the slope and vibrating piezometers to monitor groundwater levels.  DBA and ALDOT will monitor the bridge and slope, intending to be able to measure displacement and calculate strain and loads in the shafts should the slope move again in the future.

Foundations were completed a few days ahead of schedule at the end of July 2020.  The deadline to have the bridge open to traffic was early December, 2020, but Brasfield and Gorrie had an aggressive plan to complete the project early and earn the bonus for early completion.   The bridge was open to traffic September 28, 2021 to much rejoicing among the commuters and others that use this route.   Volkert was the CE&I Consultant on the project for ALDOT, providing construction management and inspection services for the project, ensuring all requirements were met to build the bridges.

To read more in detail about the design and construction of the bridge foundations, we published an article i nthe April 2021 issue of Foundation Drilling Magazine:

Thompson, W.R. and Dapp, S.D. (2021). “Innovative Landslide Solution”, Foundation Drilling, Vol XLII, No. 3April 2021, pp51-62.

Click HERE for some of the photos DBA team members have taken during construction.

To see aerial views from ALDOT’s UAV flight taken on July 10, 2020, click HERE.

 

 

FHWA GEC 10 Update for 2018 Released!

UPDATE!  Posting of the PDF to the FHWA Resource page has been delayed while the formatting issues noted below are worked out. 

CLICK HERE for a Final DRAFT for use until FINAL document is posted by FHWA.

The long anticipated update to FHWA GEC 10 Drilled Shafts: Construction Procedures and Design Methods has finally been released by FHWA, The same team that authored the major update in 2010 that shifted design from ASD to LRFD also completed this update: Dr. Dan Brown, P.E., D.GE, and Dr. John Turner, P.E., D.GE of DBA, Dr. Erik Loehr, P.E. of the University of Missouri and DBA, and Mr. Ray Castelli, P.E. of WSP.

This version is an update of the 2010 publication.  A complete list of changes made since 2010 is in the opening chapter.  Some of the revisions include:

  • streamlining materials covered in other GEC publications (for example, site investigation and lateral loading) to focus on aspects particular or unique to drilled shafts;
  • updates to reflect the evolution of construction procedures, tooling, materials, drilling fluids, and concrete placement;
  • updated design equations for axial loading, particularly for earthquake loading;
  • updated group design to reflect recent changes to AASHTO design guidelines;
  • updates on integrity testing (including use of Thermal Integrity Profiling, or TIP); and,
  • an outline for a process for assessment and acceptance of drilled shafts based on inspection records and integrity tests.

You can download the new PDF here.  The PDF posted is “preliminary” with some minor formatting and other items to be cleaned up by the fall.

Pre-Bid Load Testing for the Mobile River Bridge and Bayway Public Private Partnership (P3) Project

DBA has been fortunate to be involved as a consult to Alabama Department of Transportation (ALDOT) for the  Mobile River Bridge and Bayway Project.  This project represents Alabama’s largest ever investment for a single infrastructure project.  The project includes a cable stayed bridge over the Mobile River and seven miles of bridge over Mobile Bay.  Bridge foundations therefore represent a major component of the estimated $2 billion project cost.  DBA serves as a foundation consultant under subcontract to Thompson Engineering, Inc..  Thompson is one of the ALDOT Advisory Team partners, the other partners being HDR and Mott MacDonald.

With the tremendous volume of foundations required for the project, the DBA/Thompson team worked with ALDOT’s Geotechnical Division to develop a pre-bid load test program to help reduce some of the risks that would face both ALDOT and prospective concessionaires.  Performing a deep foundation load test program during the procurement phase of a Public Private Partnership (P3) project can help the prospective concessionaires better define foundation design parameters and reduce uncertainties and risks related to constructability of the foundations.  The reduced risk leads to reduced costs by allowing the concessionaire to develop a more efficient design while minimizing contingency costs and potential delays related to foundation constructability or performance.

The load test program was designed to include the most likely foundation types that the prospective teams might use.  Several types of driven piles were installed and tested, including typical square and cylinder concrete piles used on the Alabama coast plus steel H-piles and an open-ended steel pipe pile.

All driven piles were subject to dynamic testing with a Pile Driving Analyzer during driving.  Restrikes with dynamic testing were conducted on all driven piles to evaluate potential strength gain with time.  Jetting techniques were specified for some piles to evaluate this installation technique which could potentially be used during construction.

Traditional axial static load tests were performed on steel HP14x89 and 18in Precast Prestressed Concrete (PPC) square piles.  Rapid (Statnamic) axial load tests were performed on 36 in PCC square piles, 54in PCC cylinder, and 60in steel open-end pipe piles.

A 72in diameter drilled shaft foundation was also installed and tested.  Axial load testing was done using a bi-directional load cell (AFT A-Cell).  Lateral load testing was done using the Statnamic device.

 

Here are some videos of the Statnamic testing, with slow motion action!

 

Foundation contractors that are part of a concessionaire team pursuing the project were allowed to bid the load test program.  Jordan Pile Driving was the successful bidder for the $3.7 million test project.  AFT provided the testing services for the project – dynamic, static, Statnamic, and A-Cell.

A summary of the results can be found in a presentation made to ALDOT at the 62nd Annual Alabama Transportation Conference on February 13, 2019.   (Click HERE to get the presentation). Publication of the results is anticipated to be made in the DFI Journal in the future.

Goethals Bridge – Up and out of the ground

(Post and photos provided by John Turner, Ph.D., P.E., D.GE of DBA.)

DBA has had the privilege to be the geotechnical/foundation engineer for the Goethals Bridge Replacement (GBR)Project, a design-build project for the Port Authority of New York & New Jersey (PANYNJ). The project will replace the existing Goethals Bridge that was built in the 1920s and carries I-278 over the Arthur Kill River between Elizabeth, New Jersey and Staten Island, New York.

Construction of drilled shafts continues as the superstructure begins to emerge over the skyline between Elizabeth, NJ and Staten Island, NY.  The new bridge will be a dual-span 1,983-ft long cable-stayed bridge with approach spans of over 2,500 ft on each side.  The bridge is supported on over 200 drilled shaft foundations ranging in diameter from 4.5 ft to 10 ft and socketed into Passaic Formation siltstone.

Goethals April 2016

The GBR is a Public-Private Partnership (P3) that represents a major milestone for the PANYNJ in its distinguished history of bridge building in the greater New York City metropolitan area.  The existing Goethals Bridge along with the Outerbridge Crossing and the Bayonne Bridge comprise the three Port Authority bridges connecting Staten Island with New Jersey.  The Goethals Bridge and the Outerbridge Crossing are cantilever truss structures and both opened on the same day in 1928. They were designed by J.A.L. Waddell under the supervision of the eminent engineer Othmar H. Ammann (1879-1965), who was the designer of many other iconic bridges in the NY City area including the Bayonne Bridge (1931), the George Washington Bridge (1931), and the Verrazano Narrows Bridge (1964).  The designer of record for the replacement Goethals Bridge is Parsons Corporation, which is the successor firm of Robinson & Steinman, whose principal David B. Steinman was also a notable NY area bridge designer and a contemporary and rival of O.H. Ammann.

Each main pylon tower of the GBR is supported on a group of six 9-ft diameter drilled shafts and each anchor pier is supported by two 10-ft diameter shafts.  Approach piers are two-column bents with each column supported on a rock-socketed drilled shaft.

Goethals shaft 1

DBA is the foundation design engineer of record and this project provides an example of how rock-socketed drilled shafts can provide a reliable and cost-effective means of supporting a major bridge by taking advantage of the high resistances that can be achieved.  Key factors involved in taking advantage of rock sockets for this project were:  (1) load testing to demonstrate high axial resistances (>30 ksf side resistance and  >300 ksf base resistance), (2) utilization of all relevant construction QC/QA tools to ensure that rock sockets are constructed in a manner that is consistent with construction of the load-tested shafts that provide the basis of the design, (3) close collaboration between all members of the design-build team, and (4) adequate subsurface characterization, especially a thorough characterization of rock characteristics and their effect on socket resistances. Load testing for this project demonstrates that side and base resistances can be used in combination to design rock socketed shafts for axial loading.  This approach avoids the use of unnecessarily deep sockets, thereby minimizing the associated construction risks and costs.

Goethals rendering

The GBR project developer is NYNJ Link Developer, LLC and construction is being performed by a joint venture of Kiewit-Weeks-Massman (KWM).  Parsons is the lead designer.  A construction web-cam and additional information on the GBR can be found at the Port Authority’s website: http://www.panynj.gov/bridges-tunnels/goethals-bridge-replacement.html

Drilled Shafts Complete at St Croix

Pier 9 FootingAs reported by the Minneapolis Star Tribune, Case Foundation recently finished constructing 40 drilled shafts at the St Croix River Crossing Project.  Since early June, Case has been working at a feverish pace to construct the drilled shaft foundations for the new extradosed bridge between Minnesota and Wisconsin.  As of November 8th, all of the drilled shafts are officially complete.  General contractor Kramer is working to finish the pier footings and support tower bases by early 2014.  Soon, the joint venture of Lunda and Ames will begin construction of the $380 million bridge superstructure.

As MnDOT’s foundation consultant for the project, DBA has been on site during much of the foundation construction over the past five months.  Some pictures taken during this time, along with several pictures from MnDOT are available for viewing on our Picasa Page.  More pictures and information can be found on the project website and Facebook Page, and the project can be viewed live via webcam.  Previous DBA blog posts about the main project and the predesign load test program can be found here.

DBA is pleased to wrap up its role on the St Croix Crossing Project with a very positive outlook.  The drilled shaft construction proceeded on schedule and as planned without unexpected challenges, and our strong client relationships with MnDOT continued to grow stronger.  It was also nice to see familar faces from Case, Braun Intertec, and Parsons Transportation Group, many of whom we worked with us at Hastings.  We very much look forward to working with these partners again in the future!

Missouri Bridge Project Updates–Hurricane Deck and MRB

Time for a quick update on two projects owned by MoDOT on which DBA was involved.

First, the official opening of the Missouri Route 5 – Hurricane Deck Bridge Replacement was held on September 7th.

Hurricane Deck

History was made on Sept. 7, 2013when state and local officials cut the ribbon on the new Hurricane Deck Bridge during a ceremony held in the center of the new structure.  The bridge officially opened to traffic in the late evening on Monday, Sept. 9. The original bridge is now closed and will be prepared for demolition during the remainder of 2013. Final demolition will take place in the spring of 2014.

Check out this time lapse video of the bridge being built.

 

Last, the new Mississippi River Bridge in St. Louis.

Clipboard01

They have closed the gap on the bridge – lots of neat photos here showing the final deck panels in place.  Here they are placing the final edge girders.  Finally, here is a link to the live construction cameras.

St. Croix Bridge Construction Starts with Official Groundbreaking

St Croix Aerial Rendering

Earlier this week, officials from the Minnesota and Wisconsin departments of transportation (MnDOT and WisDOT) met for an official groundbreaking ceremony on the projected $629 million bridge and highway project that will connect Oak Park Heights, Minnesota, to St. Joseph, Wisconsin, just south of Stillwater, Minnesota, as highlighted in yesterday’s edition of The Minneapolis St. Paul Business Journal.  The new bridge will replace the 80-year-old Stillwater Lift Bridge and relieve traffic congestion in nearby Stillwater.

DBA has been retained by MnDOT as the lead geotechnical consultant and foundation designer for the extradosed river bridge.  Last summer, DBA aided MnDOT in the design and oversight of a load test program described in my blog post, “DBA Wraps Up Load Test Program and Proceeds with Design on St. Croix Bridge.”  Following final design, which took place over the fall and winter, construction of the foundations will begin next week with the installation of a technique shaft.  DBA will participate in construction as well, providing construction observation and review of the technique shaft and at least one shaft at each of the five production piers.  Edward Kraemer & Sons, Inc. of Plain, Wisconsin, has been selected as the general contractor for the foundation contract with sub-contractor Case Foundation Company of Chicago, Illinois, performing the drilling.  The extradosed bridge will feature five main river towers, each resting on two footings supported by a 4-shaft group of 8.5-foot drilled shafts, socketed 25-feet or more into sandstone bedrock.

I hope to have some more updates soon with some pictures following my upcoming site visits to observe the construction operations.  In the mean time, you can stay updated by visiting the MnDOT project page and watching the “action” live via the construction webcam.

Huey P. Long Bridge Expansion–Completion in June 2013

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The Huey P. Long Bridge in New Orleans, Louisiana will be officially completed in June this year, according to the LADOTD. A recent article in the Times-Picayune on-line announced another ramp opening last weekend, bringing the $1.2 billion project one step closer to completion.  DBA was brought onto the project by the contractor team to consult on the design, load testing, and construction of the 9-foot diameter, 184-foot long base grouted drilled shafts.

Check out our previous DBA posts on the HPL.

This article from the Times-Picayune in 2009 gives a great graphical description of how the bridge was widened.

You can learn all about the history of the bridge and the project at the project page of the Louisiana TIMED Program.  The project page has a lot of good links, including photos from the project.

Photo Credit: Louisiana TIMED project photo album

DBA Wraps Up Load Test Program and Proceeds with Design on St. Croix Bridge

Project rendering courtesy of HDR 

Lateral Statnamic test, picture by David Graham of DBA, click here for a YouTube video

DBA has been selected by MnDOT as a geotechnical and load testing consultant for the design phase load test program and foundation design of a new bridge crossing the the St. Croix River near Oak Park Heights and Stillwater, Minnesota. The new bridge will carry State Highway 36 across the St. Croix River between Minnesota and Wisconsin. Currently, Highway 36 is carried on an 80-year old two-lane vertical lift bridge in downtown Stillwater.  The new bridge will divert the heavy through traffic away from the historic downtown center and reduce travel time for commuters.  The iconic lift bridge will be converted to a pedestrian and bicycle only structure.

Work began this summer on the load test program which consisted of one 8-foot test shaft, two 24-inch driven steel pipe piles, and two 42-inch driven steel pipe piles, all installed in the St. Croix River along the alignment of the new bridge.  Local contractor Carl Bolander & Sons Co. was selected as the general contractor for the load testing program.  Bolander self-performed the installation of the test piles and sub-contracted the construction of the test shaft to Case Foundation Company, of Chicago, Illinois.  Axial load testing of the test shaft was performed by Loadtest, Inc., of Gainesville, Florida, using Osterberg Cells (O-cells).  Dynamic testing of the driven piles using the pile driving analyzer (PDA) was performed by local geotechnical consultant Braun Intertec.  Axial testing of the driven piles and lateral testing of the shaft and one of each size pile was performed using the Statnamic Device by Applied Foundation Testing, Inc. (AFT), of Jacksonville, Florida.  DBA provided pre-test recommendations, assisted MnDOT in construction oversight, provided analysis and review of the test results, and made design recommendations based on the test results.

Following the successful load test program, DBA is working with MnDOT’s structural design consultants for the project, HDR, Inc. and Buckland & Taylor Ltd.  to optimize the bridge design.  Already, the design team has been able to lengthen the bridge spans and eliminate a river pier as a result of the load test results, as was recently reported by Minnesota Public Radio (MPR).  Also, because the total number of drilled shafts required to support the main pier towers has been reduced, construction on the foundations will been moved up to 2013 rather than the original estimated start date in 2014, also reported by MPR.

For more information, please see:

The MnDOT Project Page

The DBA Project Summary Sheet