U.S. Department of Transportation Publication No. FHWA-NHI-14-007 Federal Highway Administration FHWA GEC 007 February 2015 NHI Course No. 132085 Soil Nail Walls Reference Manual Developed following: AASHTO LRFD Bridge Design Specifications, 7th Edition. NOTICE The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect policy of the Department of Transportation. This report does not constitute a standard, specification, or regulation. The United States Government does not endorse products or manufacturers. Trade or manufacturers′ names appear herein only because they are considered essential to the objective of this document. Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA-NHI-14-007 4. Title and Subtitle 5. Report Date GEOTECHNICAL ENGINEERING CIRCULAR NO. 7 February 2015 SOIL NAIL WALLS - REFERENCE MANUAL 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Carlos A. Lazarte, PhD, PE, GE; Helen Robinson, PE; Jesús E. Gómez, PhD, PE; Andrew Baxter, PE, PG; Allen Cadden, PE*; Ryan Berg, PE† 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) †Ryan R. Berg & Associates, Inc., Woodbury, MN 55125 11. Contract or Grant No. DTFH61-13-T-70011 *Schnabel Engineering, Rockville, MD 20850 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered National Highway Institute U.S. Department of Transportation Federal Highway Administration, Washington, DC 20590 14. Sponsoring Agency Code 15. Supplementary Notes FHWA COTR: Heather Shelsta FHWA Technical Working Group Leader: Barry Siel, PE FHWA Technical Working Group: Silas Nichols, PE; Scott Anderson, PE; Khalid Mohamed, PE; Vernon Schaefer, PhD, PE; and Richard Barrows, PE 16. Abstract This document presents information on the analysis, design, and construction of permanent soil nail walls in highway applications. The main objective is to provide practitioners in this field with sound and simple methods and guidelines that will allow them to analyze, design, construct, and inspect safe and economical structures. This document updates the information contained in FHWA0-IF-03-017 (Lazarte et al. 2003). The focus is on soil nailing techniques that are commonly used in U.S. practice. The contents of this document include: an introduction; chapters on applications and feasibility, construction materials and methods, information required for design, analysis and design of soil nail walls, corrosion protection; and chapters on contracting approach, technical specifications and design examples. This manual introduces a framework for the design of soil nail walls that takes into account factors of safety used in the ASD method while integrating LRFD principles. 17. Key Word 18. Distribution Statement Soil nail, soil nail wall design, LRFD, ASD, earth- retaining structures, construction, soil nail load No restrictions. test, facing, shotcrete, specifications. 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 425 Form DOT F 1700.7 Reproduction of completed page authorized CONVERSION FACTORS Approximate Conversions to SI Units Approximate Conversions from SI Units When You Know Multiply By To Find When You Know Multiply By To Find (a) Length inch (in.) 25.4 millimeter (mm) millimeter (mm) 0.039 inch (in.) foot (ft) 0.305 meter (m) meter (m) 3.28 foot (ft) yard (yd) 0.914 meter (m) meter (m) 1.09 yard (yd) mile (mi) 1.61 kilometer (km) kilometer (km) 0.621 mile (mi) (b) Area square inches (in2) 645.2 square millimeters (mm2) square millimeters (mm2) 0.0016 square inches (in2) square feet (ft2) 0.093 square meters (m2) square meters (m2) 10.764 square feet (ft2) Acres (ac) 0.405 hectares (ha) hectares (ha) 2.47 Acres (ac) square miles (mi2) 2.59 square kilometers (km2) square kilometers (km2) 0.386 square miles (mi2) square inches (in2) 645.2 square millimeters (mm2) square millimeters (mm2) 0.0016 square inches (in2) (c) Volume fluid ounces (oz) 29.57 milliliters (mL) milliliters (mL) 0.034 fluid ounces (oz) Gallons (gal) 3.785 liters (L) liters (L) 0.264 Gallons (gal) cubic feet (ft3) 0.028 cubic meters (m3) cubic meters (m3) 35.32 cubic feet (ft3) cubic yards (yd3) 0.765 cubic meters (m3) cubic meters (m3) 1.308 cubic yards (yd3) (d) Mass ounces (oz) 28.35 grams (g) grams (g) 0.035 ounces pounds (lb) 0.454 kilograms (kg) kilograms (kg) 2.205 pounds short tons (2000 lb) (T) 0.907 megagrams (tonne) (Mg) megagrams (tonne) (Mg) 1.102 short tons (2000 lb) (e) Force pound (lb) 4.448 Newton (N) Newton (N) 0.2248 pound (lb) (f) Pressure, Stress, Modulus of Elasticity pounds per square foot (psf) 47.88 Pascals (Pa) Pascals (Pa) 0.021 pounds per square foot (psf) pounds per square inch (psi) 6.895 kiloPascals (kPa) kiloPascals (kPa) 0.145 pounds per square inch (psi) (g) Density kilograms per cubic meter kilograms per cubic meter pounds per cubic foot (pcf) 16.019 0.0624 pounds per cubic feet (pcf) (kgm3) (kgm3) (h) Temperature Fahrenheit temperature (oF) 5/9(oF- 32) Celsius temperature (oC) Celsius temperature (oC) 9/5(oC)+ 32 Fahrenheit temperature (oF) Notes: 1) The primary metric (SI) units used in civil engineering are meter (m), kilogram (kg), second (s), Newton (N), and Pascal (Pa=N/m2). 2) In a "soft" conversion, an English measurement is mathematically converted to its exact metric equivalent. 3) In a "hard" conversion, a new rounded metric number is created that is convenient to work with and remember. PREFACE The purpose of this manual is to provide updated, state-of-the-practice information for selecting, designing, and constructing soil nail walls for roadway projects. The information contained herein is aimed at producing safe and cost-effective designs, and to help owners identify and manage the risks associated with soil nail wall projects. This manual focuses solely on soil nail systems for long-term support of excavations and does not specifically address the use of soil nails as temporary structures. This GEC serves as the FHWA reference document for highway projects involving permanent soil nail walls. Recent advances in the state-of-the-practice for this system addressed in the document include: • The implementation of the Load and Resistance Factor Design (LRFD) platform. • Information on new or emerging soil nailing technologies. • The inclusion of design examples based upon the SNAP-2 computer program. The primary audience for this document is: agency and consulting engineers specialized in bridge, structural, geotechnical, and roadway design; and engineering geologists and consulting engineers providing technical reviews, or who are engaged in the design, procurement, and construction of permanent soil nail systems. This document is also intended for management, specification and contracting specialists, as well as for construction engineers interested in design and contracting aspects of soil nail systems. In this document, the term “soil nail” refers to inclusions in soils and soft and weathered rock. The term “soil nail” is used in this document regardless of the material supported by the soil nail wall. Although this manual is focused on solid bar soil nails, Chapter 10 presents necessary considerations for the design and construction of Hollow Bar Soil Nails (HBSNs). This document draws descriptions and basic information from earlier FHWA publications in this field; in particular, the predecessor manual entitled “Soil Nail Walls,” Report FHWA0-IF-03-017 (Lazarte et al. 2003). Valuable information was also obtained from the publication entitled “Hollow Bar Soil Nails Pullout Test Program,” Publication No. FHWA-CFL/TD-10-001 (Cadden et al. 2003). ACKNOWLEDGEMENTS The authors would like to acknowledge the support provided by the FHWA Technical Working Group for this project. The authors would also like to thank those practitioners who reviewed and contributed to this document including: • James G. Collin, PhD, PE, The Collin Group, Ltd. • Terence P. Holman, PhD, PE, Geosyntec Consultants • Paul J. Sabatini, PhD, PE, Geosyntec Consultants Thanks also go to: Thomas Bird, Williams Form Engineering Corp.; Denis Ambio and Dan MacLean, Con-Tech Systems, Ltd.; John Delphia, PE, Texas DOT; and Kenneth Fishman, PhD, PE, Earth Reinforcement Testing, Inc., for their data, commentary and/or photograph contributions. The authors thank the following organizations and their representatives for providing valuable information and review of the manual: • International Association of Foundation Drilling (ADSC-IAFD) – Anchored Earth Retention Committee, Thomas Richards, PE, Nicholson • Deep Foundations Institute (DFI) – Tiebacks and Soil Nailing Committee, Chair: Edward Laczynski, PE, G.A. & F.C. Wagman, Inc. • AASHTO – T-15 Committee • ASCE – Earth Retaining Structure Committee • TRB – Foundations Committee The authors would also like to extend their gratitude for the support provided by Schnabel Engineering personnel, including: Helen Foreman; Miranda Dibert; Sixto Fernandez, PE; Phil Shull, PE; Johanna Mikitka Simon, PE; Eric Rehwoldt, PE; Timothy Hastings, EIT; Naveen Thakur, PE; Carlos Englert, PE; and Carol Butler for their assistance with review, analysis, AutoCAD, proofreading, word processing, compiling and 508 compliance. Table of Contents Cover Notice Page Technical Report Documentation Page Conversion Factors Preface Acknowledgements Table of Contents