Dear Journal Readers, DFI’s 2018 Issue #2 is a great mix of research papers, award papers, case studies, and submissions with honorable mentions received during DFI annual conference’s paper competition. Our broad mix of local and international authors will keep you interested across a broad spectrum of research and project topics and provide practical knowledge in foundation engineering, quality assurance & testing, and in-situ investigations.
This issue starts with a fresh look at a regionally developed, but nationally integrated design method, the Texas Cone Penetration (TCP) foundation design method. Moghaddam, Jayawickrama, Lawson, Surles, and Seo conduct a qualitative and quantitative assessment of the predictive validity of the TCP method based on 60 full scale load test datasets. The authors suggest that the TCP foundation design method can yield a foundation element that, when evaluated based on soil strength may not seem highly reliable, but when evaluated based on serviceability considerations (i.e., tolerable displacement) will perform exceedingly well to the point of perhaps being considered over-designed. This paper provides insight into a long-standing discussion among foundation engineers who have voiced questions about the reliability of the TCP method based on their own experiences where the method may seem to over-predict soil shear strength.
The case study on the Wanapum Dam repair prepared by the author team Stein, Hughes, Dechamps and Barkauskas presents the challenges and success story of a unique underwater repair work using post-tension anchoring systems. The dam and surrounding areas were closed after severe cracking with up to 2inch width and 65 ft length was observed in one of the dam’s monoliths. The paper describes the design review, potential damage causes, repair strategies and a step-by-step description of the construction and remedy procedures. The paper was presented during DFI’s 43rd annual conference in Anaheim.
Dr. Alessandro F. Rotta Loria was the winner of DFI’s 2018 young professor paper competition. Dr. Rotta Loria is a post-doctoral researcher at the Swiss Federal Institute of Technology in Lausanne, EPFL, and will soon commence his role as assistant professor at Northwestern University in Chicago. His research focuses on the multi-physical behavior and performance of energy foundations. His paper presents a performance-based design framework for energy piles and suggests that thermal loads involve effects that can be neglected in the design of energy piles at ultimate limit states and can be considered relevant only at serviceability limit states. Based on his finding, the performance-based design of energy piles at ultimate limit states reduces to a conventional pile design process while the design at serviceability limit states must account for a number of proposed verifications. Dr. Rotta Loria’s presentation of this paper is available online at https://m.youtube.com/watch?v=Hmi9lYfK3do.
A critical review of non-destructive testing (NDT) methodologies is provided by Prof. Joseph Coe from Temple University. Coe’s paper introduces recent advances in stress-wave NDT systems for use in assessments of in-service foundation integrity and drilled shaft construction. The research team at Temple developed a borehole testing system in a laboratory setting as a proof-of-concept study to generate high-resolution images of defects in deep foundations. The paper presents an overview of the experimental setup, the development of the testing systems including hardware, survey methods, and data processing techniques, followed by a discussion on application of the results to QA/QC of deep foundations. Coe presented this work in Anaheim in October 2018.
This issue closes with the work of an ambitious young scholar, Emily Reed, a graduate student from Tennessee Technical University, who received an honorable mention for her studies on the stability of RAP supported MSE walls. Reed and her advisor, Prof. VandenBerge conducted finite element analyses (FEA) to compare the results of FEA models with a simpler analytical bearing capacity method that uses Meyerhof’s load inclination correction factors. In particular, cases where rammed aggregate piers (RAPs) support a mechanically stabilized earth (MSE) retaining wall were examined. The FEA models were two-dimensional, and executed in the program Rocscience RS2. The author team shows that an excellent relationship between the computed factors of safety for FEA models and the bearing capacity method, especially for factors of safety ranging from 1 to 1.5 can be obtained. At factors of safety above about 1.5, the critical failure mode becomes sliding rather than global stability, and the two methods diverge. The practical takeaway of this study offers retaining wall designers with the beneficial option of a quick and reliable check on the global stability of a retaining wall without having to spend the time and money on more expensive FEA modeling.
We hope you’ll enjoy the variety of studies presented in this issue and look forward to hearing your feedback.
2018 DFI Board of Trustees
Executive Director
Theresa Engler
Trustees 2019
President
Matthew Janes (2019)
Isherwood Associates
Vice President
Michael H. Wysockey (2019)
Thatcher Engineering Corporation
Treasurer
Gianfranco Di Cicco (2019)
GDConsulting LLC
Secretary
James O. Johnson (2019)
Condon-Johnson & Associates, Inc.
Past President
Dan Brown (2019)
Dan Brown and Associates, PC
Conrad W. Felice (2021)
C.W. Felice, LLC
Frank Haehnig (2019)
Bauer Spezialtiefbau GmbH
Gerry Houlahan (2019)
Moffatt & Nichol
Mike Kelley (2020)
DYWIDAG-Systems International
K.S. Rama Krishna (2020)
Deep Foundations Institute of India
Anne Lemnitzer (2021)
University of California Irvine
J. Erik Loehr (2021)
University of Missouri
Dan MacLean (2021)
Keller Foundations Ltd.
Matthew E. Meyer (2020)
Langan Engineering & Environmental Services
Morgan NeSmith (2021)
Berkel & Company Contractors, Inc.
David Paul (2019)
Paul GeoTek Engineering LLC
Howard Perko (2019)
Magnum Piering, Inc.
Thomas D. Richards (2020)
Nicholson Construction Company
Lori A. Simpson (2019)
Langan Engineering & Environmental Services
Martin G. Taube (2021)
Menard Group USA
Stefano Valagussa (2020)
TREVIICOS Corporation