STATE OF CALIFORNIA • DEPARTMENT OF TRANSPORTATION ADA Notice TECHNICAL REPORT DOCUMENTATION PAGE For individuals with sensory disabilities, this document is available in alternate TR0003 (REV 10/98) formats. For information call (916) 654-6410 or TDD (916) 654-3880 or write Records and Forms Management, 1120 N Street, MS-89, Sacramento, CA 95814. 1. REPORT NUMBER 2. GOVERNMENT ASSOCIATION NUMBER 3. RECIPIENT'S CATALOG NUMBER CA16-2532 4. TITLE AND SUBTITLE 5. REPORT DATE Assessment of Soil Arching Factor for Retaining Wall Pile Foundations 03/31/2017 6. PERFORMING ORGANIZATION CODE 7. AUTHOR 8. PERFORMING ORGANIZATION REPORT NO. Andre R. Barbosa, Scott A. Ashford, Henry B. Mason, Andre F. V. Belejo 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NUMBER School of Civil and Construction Engineering 101 Kearney Hall Oregon State University Corvallis, OR 97331-3212 11. CONTRACT OR GRANT NUMBER 65A0497 12. SPONSORING AGENCY AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED Department to California Department of Transportation, Final Report Division of Engineering Services, 1801 30th Street, MS #9-2/5I, 14. SPONSORING AGENCY CODE Sacramento, CA 95816 15. SUPPLEMENTARY NOTES 16. ABSTRACT Despite the prevalence of the soldier piles retaining wall systems as temporary and even permanent shoring systems along state highways, relatively little is known on the effect of the foreslope bench width and the slope inclination on the arching capability factor used in design codes and standards. A review of literature indicated that no full-scale tests were conducted for soldier pile systems and only a few components have been modeled analytically, often using 2-D analyses that cannot capture the complex 3-D behavior of the arching behavior in active and passive regions of soldier pile retaining wall systems. To help address this gap in knowledge, an analytical research program is developed herein to assess the current design procedures on soldier pile walls and make recommendations for improvement, specifically with respect to 3-D effects of soil arching, foreslope sloping ground, and bench width, based on a parametric study supported on advanced nonlinear finite element models of the soldier pile systems. Discussions on how to account for 3-D effects based on 2-D analyses and on how to account for bench width effects when classical soil theories are used in design are provided. Finally, a proposed experimental program is simulated using the modeling approaches developed in this study. 17. KEY WORDS 18. DISTRIBUTION STATEMENT Soil arching, soldier pile walls, lagging, retaining systems, soil slope, No restrictions. This document is available to the modeling public through the National Technical Information Service, Springfield, Virginia 22161 19. SECURITY CLASSIFICATION (of this report) 20. NUMBER OF PAGES 21. COST OF REPORT CHARGED None 179 Reproduction of completed page authorized. ASSESSMENT OF SOIL ARCHING FACTOR FOR RETAINING WALL PILE FOUNDATIONS FINAL PROJECT REPORT by Andre R. Barbosa, Ph.D. Scott A. Ashford, Ph.D. Henry B. Mason, Ph.D. and Andre F.V. Belejo Oregon State University May 2017 CALIFORNIA DEPARTMENT OF TRANSPORTATION DISCLAIMER This document is disseminated in the interest of information exchange. 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 the official views or policies of the State of California or the Federal Highway Administration. This publication does not constitute a standard, specification or regulation. This report does not constitute an endorsement by the Department of any product described herein. For individuals with sensory disabilities, this document is available in Braille, large print, audiocassette, or compact disk. To obtain a copy of this document in one of these alternate formats, please contact: the Division of Research and Innovation MS-83, California Department of Transportation, P.O. Box 942873, Sacramento, CA 94273-0001. ACKNOWLEDGMENTS Input and comments from the technical advisory team are sincerely appreciated. The team would like to thank Frank McKenna and Pedro Arduino for working on improving the OpenSees models and tools needed for the research developed herein. In addition, the team would like to thank Dr. Minjie Zhu for discussions and developments of Paraview used extensively in the visualization of the results of the numerical models. This work was funded by California Department of Transportation under Agreement #65A0497. EXECUTIVE SUMMARY Despite the prevalence of the soldier piles retaining wall systems as temporary and even permanent shoring systems along state highways, relatively little is known on the effect of the foreslope bench width and the slope inclination on the arching capability factor used in design codes and standards. A review of literature indicated that no full-scale tests were conducted for soldier pile systems and only a few components have been modeled analytically, often using 2-D analyses that cannot capture the complex 3-D behavior of the arching behavior in active and passive regions of soldier pile retaining wall systems. To help address this gap in knowledge, an analytical research program is developed herein to assess the current design procedures on soldier pile walls and make recommendations for improvement, specifically with regard to 3-D effects of soil arching, foreslope sloping ground and bench width, based on a parametric study supported on advanced nonlinear finite element models of the soldier pile systems. Discussions on how to account for 3-D effects based on 2-D analyses and on how to account for bench width effects when classical soil theories are used in design are provided. Finally, a proposed experimental program is simulated using the modeling approaches developed in this study. TABLE OF CONTENTS Page 1 INTRODUCTION .......................................................................................................... 11 1.1 OBJECTIVE OF THIS STUDY ............................................................................... 11 1.2 ORGANIZATION OF THIS REPORT .................................................................... 12 2 LITERATURE REVIEW ............................................................................................... 14 2.1 OVERVIEW ............................................................................................................. 14 2.2 EFFECTS OF SOIL ARCHING AND SLOPE ON PILES AND RETAINING WALLS 14 Soil Arching Theory and Experimental Tests ................................................... 14 Soil Arching and Slopes.................................................................................... 16 Effects of Soil Slope on Lateral Capacity of Piles ............................................ 21 2.3 CRITERIA FOR DESIGN AND ANALYSIS ......................................................... 25 Design Procedures ............................................................................................ 25 Analysis Procedures .......................................................................................... 26 2.4 SUMMARY .............................................................................................................. 28 3 METHODOLOGY FOR ASSESSMENT OF THE ARCHING FACTOR................... 31 3.1 OVERVIEW ............................................................................................................. 31 3.2 DEFINITION OF CASE STUDIES ......................................................................... 31 Soil Definition ................................................................................................... 31 i Parameter Selection .......................................................................................... 33 3.3 PARAMETRIC CASE STUDY ............................................................................... 34 Soldier Pile Design ........................................................................................... 34 Development of Numerical Models .................................................................. 39 Pushover Analysis Methodology ...................................................................... 47 Analysis of Results / Post-processing ............................................................... 49 Assessment of the Arching Capability Factor .................................................. 50 4 FINITE ELEMENT RESULTS AND DISCUSSION ................................................... 52 4.1 OVERVIEW ............................................................................................................. 52 4.2 SOLDIER PILE DESIGN......................................................................................... 52 4.3 THEORETICAL PASSIVE RESISTANCE VALUES ............................................ 56 4.4 2-D PLAN ANALYSIS RESULTS .......................................................................... 58 4.5 3-D MODEL RESULTS ........................................................................................... 63 Effect of load distribution and detachment effects ........................................... 63 Validation of the 3-D Modeling Approach ....................................................... 67 Nonlinear Static Pushover Analysis Results ..................................................... 72 5 ARCHING CAPABILITY FACTOR ASSESSMENT ................................................. 83 5.1 Overview ................................................................................................................... 83 5.2 Effect of Bench Width .............................................................................................. 83 5.3 Effect of Soldier Pile Retaining Wall Geometry: Wall height and pile spacing ...... 86 ii 5.4 Effect of Analysis Dimensionality: 2-D versus 3-D analysis ................................... 90 6 PROPOSED REVISIONS TO THE PASSIVE RESISTANCE EQUATION .............. 93 7 SIMULATION OF A PROPOSED EXPERIMENTAL PROGRAM ........................... 96 7.1 OVERVIEW ............................................................................................................. 96 7.2 PROPOSED EXPERIMENTAL PROGRAM .......................................................... 96 7.3 SIMULATION OF AN EXAMPLE OF A PROPOSED EXPERIMENT ............... 97 7.4 EFFECT OF LOAD DISTRIBUTION ..................................................................... 99 8 SUMMARY, CONCLUSIONS, AND SUGGESTIONS FOR FURTHER RESEARCH ...................................................................................................................................... 100 9 REFERENCES ............................................................................................................. 103 APPENDICES ............................................................................................................. AP-1 iii LIST OF FIGURES Page Figure 2-1: Load acting on the pile versus soil movement (Liang and Zeng 2002). .................... 18 Figure 2-2: Effect of variation in internal frictional angle: cohesionless soil (Liang and Zeng 2002). ................................................................................................................................................. 18 Figure 2-3: Effect of variation in cohesion (Liang and Zeng 2002). ............................................ 19 Figure 2-4: Effect of pile diameter (Liang and Zeng 2002). ......................................................... 19 Figure 2-5: Measured load versus measured pile displacement at 3 ft from ground surface for 0d, 2d, 4d, 8d piles (Nimityongsukul et al. 2012)......................................................................... 24 Figure 2-6: Comparison of Caltrans method and measured results for 0d, 2d, 4d and 8d piles (Nimityongsukul et al. 2012). ................................................................................................. 24 Figure 2-7: Cantilever retaining walls (Caltrans 2011): (a) wall deformation; (b) load distribution, (c) load simplification. ............................................................................................................ 27 Figure 3-1: Load diagram for a single layer (Caltrans 2011): (a) granular soil; (b) cohesive soil. ................................................................................................................................................. 36 Figure 3-2: Load distribution for cohesive backfill (Caltrans 2011). ........................................... 36 Figure 3-3: Cross-section of the embedded pile. .......................................................................... 37 Figure 3-4: Passive earth pressure coefficient (Caquot and Kerisel 1948). .................................. 38 Figure 3-5: 2-D Modeled soil meshes (plan view); (a) considering one strip; (b) considering three strips. ....................................................................................................................................... 40 Figure 3-6: 3-D model mesh: (a) 3-D view; (b) zoom over region of the pile; (c) elevation view ................................................................................................................................................. 42 Figure 3-7: Part of the numerical model created in OpenSeesPL and adjusted using TCL scripts for modeling the HP section above the excavation line. ......................................................... 42 iv