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2019 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 915 Relationship Between Erodibility and Properties of Soils J.-L. Briaud I. Shafii H.-C. Chen Z. Medina-Cetina Texas a&M TransporTaTion insTiTuTe College Station, TX Subscriber Categories Bridges and Other Structures â¢ Geotechnology Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniquesâthe National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRBâs recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRBâs relationship to the National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs identified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the Federal Highway Administration. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&Iâs recommendations are proposed to the AASHTO Board of Direc- tors and the National Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Academies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement, rather than to substitute for or duplicate, other highway research programs. Published research reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet by going to http://www.national-academies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 915 Project 24-43 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-48075-8 Library of Congress Control Number 2019950229 Â© 2019 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The research report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied committees, task forces, and panels annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.
C O O P E R A T I V E R E S E A R C H P R O G R A M S AUTHOR ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 24-43 by the Texas A&M Trans- portation Institute, Texas A&M University System (TAMU). Jean-Louis Briaud, P.E., Distinguished Professor of Civil Engineering at TAMU, was the project director and principal investigator. The other authors of this report are Iman Shafii, research assistant and doctoral candidate, TAMU (currently geotechnical engineer, Fugro USA Land); Hamn-Ching Chen, Joint Professor of Civil Engineering and Ocean Engineering, TAMU; and Zenon Medina-Cetina, Associate Professor of Civil Engineering, TAMU. The investigators wish to thank many people for their input and cooperation. These include Stephane Bonelli of the University of Grenoble, France; Anna Shidlovskaya of the University of Mines, Russia; and Tony Wahl of the U.S. Bureau of Reclamation. Thanks also go to Garey Fox, Professor and Department Head, Biosystems and Agricultural Engineering Department, Oklahoma State University, for providing the core part of the mini-JET device. The authors also acknowledge Mostafa Bahmani and Yichuan Zhu, both doctoral students at TAMU, for their contributions to this project; the Houston, Texas, office of Fugro USA Land, and the College Station and Conroe, Texas, offices of Terracon Consultants for providing help at many key moments during this project. Finally, the authors thank the staff and lab coordinators in the TAMU Geotechnical Engineering Program, who helped during this project and thereby made this study possible. CRP STAFF FOR NCHRP RESEARCH REPORT 915 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Camille Crichton-Sumners, Senior Program Officer Megan A. Chamberlain, Senior Program Assistant Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications Janet M. McNaughton, Senior Editor NCHRP PROJECT 24-43 PANEL Field of Soils and GeologyâArea of Mechanics and Foundations John G. Delphia, Texas DOT, Austin, TX (Chair) Nathalia R. Chandler, South Carolina DOT, Columbia, SC Leo L. Fontaine, Connecticut DOT, Newington, CT Martin W. McIlroy, MGE Engineering, Sacramento, CA Vernon R. Schaefer, Iowa State University, Ames, IA Heather Z. Shoup, Illinois DOT, Springfield, IL Ming Xiao, Pennsylvania State University, University Park, PA Jennifer E. Nicks, FHWA Liaison
NCHRP Research Report 915: Relationship Between Erodibility and Properties of Soils pro- vides state transportation geotechnical engineers, hydraulic engineers, structural engineers, and other practitioners with a detailed analysis and a searchable MicrosoftÂ® Excel spread- sheet, NCHRP-Erosion, that uses statistical techniques to relate geotechnical properties to soil erodibility. Downloadable from the TRB summary web page for this report (search trb.org for âNCHRP Research Report 915â), NCHRP-Erosion is a searchable database that includes compiled erosion data from the literature review and a plethora of erosion tests. It contains equations that may be used to estimate the erosion resistance of soil and determine whether erosion tests are needed. Analysis of the erodibility of geomaterials is important for the study of problems related to soil erosion such as bridge scour, embankment overtopping erosion, and stream stability. Erodibility is a relationship between the soil erosion rate and fluid velocity or hydraulic shear stress. Since different soils have different geotechnical properties, their erosion rates vary. Additionally, existing laboratory and field erosion soil tests yield varied results that make it difficult to achieve consistent and reliable estimates. Under NCHRP Project 24-43, Texas A&M University (TAMU) was asked to develop equations that quantify soil erodibility on the basis of soil properties. Two approaches were used: (1) development of correlations between the elements of the erosion function (critical velocity, critical shear stress, and slope of the erosion function) with basic soil properties (e.g., plasticity index, mean grain size, unit weight, and shear strength) and (2) use of erosion categories to develop best fit models where the erosion function fits in a zone between boundaries to be directly associated with a single category of the erosion function so that correlations with soil properties can be developed. TAMU completed an extensive literature search compiling erosion data from multiple sources worldwide and conducted hundreds of erosion and geotechnical property tests. Following detailed statistical analysis, a searchable Microsoft Excel spreadsheet that relates geotechnical properties to soil erodibility was developed. This spreadsheet, NCHRP- Erosion, can be downloaded from the TRB summary web page for NCHRP Research Report 915. Through the use of numerical simulations, the researchers also compared soil erosion test methods to inform test method selection. NCHRP Research Report 915 should be helpful for those responsible for geotechnical analysis within state transportation agencies and other practitioners. F O R E W O R D By Camille Crichton-Sumners Staff Officer Transportation Research Board
Five appendices to NCHRP Research Report 915 are gathered in an Appendices Report that is available on the NCHRP Project 24-43 web page on the TRB website (trb.org): Appendix 1: Erosion Test Results Spreadsheets, Appendix 2: Geotechnical Properties Spreadsheets, Appendix 3: First and Second Order Statistical Analyses Results, Appendix 4: Deterministic Frequentist Regression Analysis, and Appendix 5: Probabilistic Calibration Results.
1 Summary 11 Chapter 1 Introduction 11 1.1 Definition of Erosion 13 1.2 Soil Erodibility and Constitutive Models 15 1.3 Erodibility Parameters 17 1.4 Research Approach and Project Tasks 20 Chapter 2 Existing Erosion Tests 20 2.1 Laboratory Erosion Testing 47 2.2 Field Erosion Testing 55 2.3 Summary 56 Chapter 3 Existing Correlations Between Soil Erodibility and Soil Properties 56 3.1 Existing Correlations 69 3.2 Influence Factors on Erosion 76 Chapter 4 Erosion Experiments 76 4.1 TAMU Soil Erosion Lab and Testing Devices 84 4.2 Test Plan Matrix 85 4.3 Results of Erosion Tests 115 4.4 Soil Geotechnical Properties 117 Chapter 5 Organization and Interpretation of the Data 117 5.1 Development and Organization of NCHRP-Erosion 121 5.2 Column Contents in NCHRP-Erosion 125 5.3 NCHRP-Erosion Manual 138 Chapter 6 Comparison of Selected Soil Erosion Tests by Numerical Simulation 138 6.1 Results of Numerical Simulation for Nonerodible Soils 153 6.2 Results of Numerical Simulation Including Erosion 168 Chapter 7 Development of Correlation Equations 168 7.1 Determining Erosion Resistance Using the USCS 178 7.2 Plots of Critical Velocity and Shear Stress Versus Mean Particle Size 178 7.3 Deterministic (Frequentist) Regression Analysis 258 7.4 Probabilistic (Bayesian) Analysis 280 Chapter 8 Most Robust Correlation Equations 280 8.1 Differences Between the EFA, JET, and HET 280 8.2 Deterministic Analysis (Frequentist Regression) C O N T E N T S
301 Chapter 9 Conclusions and Recommendations 301 9.1 Summary of Chapters 1 Through 8 306 9.2 Recommendations on How to Approach Erosion-Related Design Problems 307 9.3 Example Applications 316 9.4 General Observations on the Effect of Geotechnical Properties on Soil Erodibility 318 Symbols and Abbreviations 320 References 325 Bibliography 327 Appendices Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.