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.
The Transportation Research Board (TRB) has released a synthesis report prepared by Dan and Robert on large diameter piles: NCHRP Synthesis 478, Design and Load Testing of Large Diameter Open-Ended Driven Piles. The report is a summary of the state of practice with regard to Large Diameter Open-Ended Piles (LDOEPs) in the transportation industry. We conducted a survey of state DOTs as well as interviews with private practitioners to summarize current practices as well as recommend best practices with regard to the selection, design, installation, and testing of LDOEPs. Several state DOTs are using LDOEPs more regularly where large foundation loads may exist and/or the piles are subject to significant unsupported length due to scour, liquefaction, or very weak surficial soils. Marine construction conditions also favor the use of these piles, particularly where pile bents might be employed to eliminate footings.
You can download a PDF of the report or purchase a hard copy at the link below.
The design-build team Tappan Zee Constructors that is building the Tappan Zee Bridge is installing the over 200-ft long steel pipe piles using a relatively simple concept to mitigate vibration impacts on fish – a bubble curtain. Such curtains have become more common as an approach to mitigate potential impacts (pardon the pun) on aquatic life when large piles are driven over water. The vibrations from the hammer impact on the pile during driving are reduced or dampened by a curtain of bubbles generated around the pile by compressed air. An item in the December 26th ASCE Smart Brief linked an article in The Journal News (White Plains, NY) highlighting the use of the curtain on the Tappan Zee project.
A rubber-looking sleeve covered the hammer where it met the pile, dampening some of the noise in the air. Underwater, however, it was a curtain of bubbles serving as the aquatic equivalent of earplugs for fish and other creatures in the Hudson River.
Aluminum rings are slid over the pilings like the rings on a shower curtain rod before any banging starts. Air pumped into the rings produces a sheath of bubbles in the water around the pile. The froth generated in the water is called a bubble curtain.
“Bubble curtains are designed to protect the fish in the area from the noise generated by the hammer impact below the water level,” said Walter Reichert, project manager for Tappan Zee Constructors. “This divides the water into basically two sections. It greatly reduces the sound waves.”
As involved as we are in the deep foundations industry (and just returning from the DFI annual conference), it seemed appropriate to take time to highlight several upcoming events in the industry. All of these are great opportunities to get PDH credits, do some networking, and build relationships in the deep foundations industry. Most are cooperative efforts of one or more of the G-I, DFI, PDCA, and ADSC. All of them have a line-up of great speakers that are leaders in the industry. Click on the links below to learn more about each one.
The DICEP conference will present modern approaches to maximize Efficiency, Effectiveness and Economy (E3) of driven piles through a series of presentations including driven pile design, testing, evaluation and case studies. Steel sheet pile design and corrosion protection are also addressed.
The program will feature presentations by leading industry design engineers and civil engineering contractors on some problems encountered with drilled shaft foundations and how those problems were solved.
Cover Image of the Hastings Mississippi River Arch Bridge
The featured article in the July/August 2013 issue of Deep Foundations, the magazine of the Deep Foundations Institute, is coauthored by Dan, Paul, and Rich Lamb, P.E., of the Minnesota Department of Transportation (MnDOT). The article summarizes how load testing has been used successfully as part of the foundation design process by DBA and MnDOT on five major bridge projects along the Mississippi and St. Croix Rivers during the last 10 years and the lessons learned from these successive projects. The featured bridge projects include two major design-build projects, the emergency replacement of the I-35W St. Anthony Falls Bridge (2007) and the Hastings Mississippi River Arch Bridge (2011). The other traditional design-bid-build projects include the I-494 Wakota Mississippi River Bridge, the U.S. Hwy 52 Lafayette Mississippi River Bridge, and the St Croix River Bridge. As is often the case, each of these projects presented unique geological and hydrogeological challenges to foundation design – despite the projects all being within 30 miles of each other – including thick layers of highly organic compressible soils overlying bedrock, layers of cobbles and boulders, artesian groundwater conditions, and bedrock ranging from weak weathered sandstone to very hard dolostone. These varying conditions resulted in the use and testing of a variety of foundations. Load testing “with a purpose” has proven to be an integral part of the design and construction process on these projects, as the load tests were not simply for verification of a design but provided valuable information used to optimize the designs and provide quality assurance of the construction practices.
Please read the full article here or in a copy of Deep Foundations, a bi-monthly magazine published by the Deep Foundations Institute. DFI is an international technical association of firms and individuals involved in the deep foundations and related industry. More information about DFI and how to become a member can be found at www.dfi.org.
Also see our Projects Page for more about some of these projects and our other major projects.
In the course of digging throughout the internet for data and information for a couple of projects using one of the best wifi routers, I came across some (relatively) recent research reports geared toward improving design of driven piles based on field testing. A report from The Illinois Center for Transportation at the University of Illinois at Urbana-Champaign is focused on improving pile design through increased resistance factors and nominal bearing values. A project by the Institute for Transportation at Iowa State University focuses on developing LRFD design procedures for steel piles in Iowa. It was published in two volumes, with Volume I covering the development of LRFD calibrations and a load test database, and Volume II covering field load tests performed for the project.
I have not had time to dig into them yet, so I just offer the links and abstracts to pique your curiosity. Perhaps you may find something interesting in them, or maybe something applicable to a project. There is a lot of research going on out there for TRB and NHI, so I figure sharing interesting tidbits helps get things circulated.
Click on the name of each of the research centers above to find out what other things they are doing, available reports, etc.
Dynamic pile testing and one static load test was performed in accordance with ICT project R27-69, “Improved Design for Driven Piles Based on a Pile Load Test Program in Illinois.” The objectives of this project are to (1) increase the maximum nominal required bearing that designers can specify to reduce the number and/or weight of piles, (2) decrease the difference between estimated and driven pile lengths to reduce cutoffs and splice lengths by development of local bias factors for predictive methods used in design, (3) increase reliance of pile setup to increase the factored resistance available to designers, (4) reduce the risk of pile driving damage during construction, and (5) increase the resistance factor (decrease in factor of safety) based on increased data and confidence from load tests in and near Illinois. Project deliverables can be categorized as (1) better prediction methods for stresses during driving, (2) better prediction methods for pile capacities using resistance factors for driven piling based on local calibrations that consider the effects of pile setups, and (3) collections of static and dynamic load test data focused on Illinois soils and geology.
For well over 100 years, the Working Stress Design (WSD) approach has been the traditional basis for geotechnical design with regard to settlements or failure conditions. However, considerable effort has been put forth over the past couple of decades in relation to the adoption of the Load and Resistance Factor Design (LRFD) approach into geotechnical design. With the goal of producing engineered designs with consistent levels of reliability, the Federal Highway Administration (FHWA) issued a policy memorandum on June 28, 2000, requiring all new bridges initiated after October 1, 2007, to be designed according to the LRFD approach. Likewise, regionally calibrated LRFD resistance factors were permitted by the American Association of State Highway and Transportation Officials (AASHTO) to improve the economy of bridge foundation elements. Thus, projects TR-573, TR-583 and TR-584 were undertaken by a research team at Iowa State University’s Bridge Engineering Center with the goal of developing resistance factors for pile design using available pile static load test data. To accomplish this goal, the available data were first analyzed for reliability and then placed in a newly designed relational database management system termed PIle LOad Tests (PILOT), to which this first volume of the final report for project TR-573 is dedicated. PILOT is an amalgamated, electronic source of information consisting of both static and dynamic data for pile load tests conducted in the State of Iowa. The database, which includes historical data on pile load tests dating back to 1966, is intended for use in the establishment of LRFD resistance factors for design and construction control of driven pile foundations in Iowa. Although a considerable amount of geotechnical and pile load test data is available in literature as well as in various State Department of Transportation files, PILOT is one of the first regional databases to be exclusively used in the development of LRFD resistance factors for the design and construction control of driven pile foundations. Currently providing an electronically organized assimilation of geotechnical and pile load test data for 274 piles of various types (e.g., steel H-shaped, timber, pipe, Monotube, and concrete), PILOT (http://srg.cce.iastate.edu/lrfd/) is on par with such familiar national databases used in the calibration of LRFD resistance factors for pile foundations as the FHWA’s Deep Foundation Load Test Database. By narrowing geographical boundaries while maintaining a high number of pile load tests, PILOT exemplifies a model for effective regional LRFD calibration procedures.
In response to the mandate on Load and Resistance Factor Design (LRFD) implementations by the Federal Highway Administration (FHWA) on all new bridge projects initiated after October 1, 2007, the Iowa Highway Research Board (IHRB) sponsored these research projects to develop regional LRFD recommendations. The LRFD development was performed using the Iowa Department of Transportation (DOT) Pile Load Test database (PILOT). To increase the data points for LRFD development, develop LRFD recommendations for dynamic methods, and validate the results of LRFD calibration, 10 full-scale field tests on the most commonly used steel H-piles (e.g., HP 10 x 42) were conducted throughout Iowa. Detailed in situ soil investigations were carried out, push-in pressure cells were installed, and laboratory soil tests were performed. Pile responses during driving, at the end of driving (EOD), and at re-strikes were monitored using the Pile Driving Analyzer (PDA), following with the CAse Pile Wave Analysis Program (CAPWAP) analysis. The hammer blow counts were recorded for Wave Equation Analysis Program (WEAP) and dynamic formulas. Static load tests (SLTs) were performed and the pile capacities were determined based on the Davisson’s criteria. The extensive experimental research studies generated important data for analytical and computational investigations. The SLT measured loaddisplacements were compared with the simulated results obtained using a model of the TZPILE program and using the modified borehole shear test method. Two analytical pile setup quantification methods, in terms of soil properties, were developed and validated. A new calibration procedure was developed to incorporate pile setup into LRFD
Here is a blast from the past on pile groups: NCHRP Report 461 – Static and Dynamic Lateral Loading of Pile Groups. I had a request for this report recently, so I found it and figured we needed to post the links to it. Dan was the lead researcher on this report during his time at Auburn University, and had an all-star line up that included Dr. Mike O’Neill and Dr. Mike McVay, two of the heavy hitters in foundation engineering. The report introduction gives a good summary of the contents:
A key concern of bridge engineers is the design and performance of pile group foundations under lateral loading events,
such as ship or ice impacts and earthquakes. This report documents a research program in which the following were developed:
(1) a numerical model to simulate static and dynamic lateral loading of pile groups, including structural and soil hysteresis and energy dissipation through radiation; (2) an analytical soil model for nonlinear unit soil response against piles (i.e., p-y curves) for dynamic loading and simple factors (i.e., p-multipliers) to permit their use in modeling groups of piles; (3) experimental data obtained through static and dynamic testing of large-scale pile groups in various soil profiles; and (4) preliminary recommendations for expressions for p-y curves, damping factors, and p-multipliers for analysis of laterally loaded pile groups for design purposes. The report also describes experimental equipment for performing site-specific, static, and dynamic lateral load tests on pile groups.
Several full-scale field tests were conducted on pile groups of 6 to 12 piles, both bored and driven, in relatively soft cohesive and cohesionless soils. All of the groups were loaded laterally statically to relatively large deflections, and groups of instrumented pipe piles were also loaded dynamically to large deflections, equivalent to deflections that might be suffered in major ship impact and seismic events. Dynamic loading was provided by a series of impulses of increasing magnitude using a horizontally mounted Statnamic device.
For a relatively short (50 pages) report, there is a lot of information packed into it gleaned from a lot of full-scale field work.
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.
A major construction feat was recently completed at the Highway 61 bridge project in Hastings, Minnesota when the 545-foot, 6.5 million-pound main bridge span was hoisted into place, 50 feet above the Mississippi river. The main span, the longest free-standing tied-arch in North America, was constructed on the shore of the Mississippi River, about a mile upstream of the river crossing. Placed on massive dollies, the span was rolled onto a set of six barges and floated downstream. Once positioned under the piers, hydraulic jacks on top of the piers slowly lifted the span into place. Around midnight on Sunday, September 23rd, 2012, the lift was complete. By noon of the following day the span was secured in place and the existing bridge was reopened to traffic. A time lapse video of the entire process can be viewed below or on YouTube.
Links to news stories published about the main span lift:
Guideline for Interpretation of Nondestructive Integrity Testing of Augered Cast-in-Place and Drilled Displacement Piles
DFI Augered Cast-In-Place Pile Committee (2011-2012) Chaired by Michael Moran
Tracy Brettmann, Principal Author; Bernard Hertlein, Matthew Meyer, Bria Whitmire, Co-Authors
(Image from DFI)
This guideline provides practical guidance for the interpretation of nondestructive testing (NDT) of the integrity of augered cast-in-place (ACIP) and drilled displacement (DD) piles. … This guideline supplements DFI’s two primary publications on ACIP piles: Augered Cast-in-Place Pile Manual (2003) and the Inspector’s Guide for Augered Cast-in-Place Piles (2010). This guideline was developed to provide 1) more detailed explanations of the various test methods available, 2) guidance on interpretation of the results, and 3) some typical examples of the data and interpretation.
Seismic and Lateral Load Design and Testing Guidelines
DFI Seismic and Lateral Loads Committee (2011-2012)
Chaired by Mark Petersen and Zia Zafir (2003-2009)
Robert Kruger, Guideline Editor
This guidance document is intended to assist geotechnical engineers, pile designers, and contractors in analysis, design, and testing of piles and drilled shafts for lateral loads. … … This document discusses the background of different analytical and testing procedures and presents the recommended methods for analysis, design and testing of piles for lateral loads.
Specialists in Deep Foundation Design, Construction, and Testing and Slope Stability Problems