Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments (2008)

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TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2008 www.TRB.org 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 REPORT 611 Subject Areas Bridges, Other Structures, and Hydraulics and Hydrology Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments Donald G. Anderson CH2M HILL Bellevue, WA Geoffrey R. Martin UNIVERSITY OF SOUTHERN CALIFORNIA Los Angeles, CA Ignatius (Po) Lam EARTH MECHANICS, INC. Fountain Valley, CA J. N. (Joe) Wang PARSONS BRINCKERHOFF INC. New York, NY Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

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CRP STAFF FOR NCHRP REPORT 611 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs David B. Beal, Senior Program Officer Eileen P. Delaney, Director of Publications Margaret B. Hagood, Editor NCHRP PROJECT 12-70 PANEL Field of Design—Area of Bridges Harry A. Capers, Jr., Arora and Associates, P.C., Lawrenceville, NJ (Chair) Darrin Beckett, Kentucky Transportation Cabinet, Frankfort, KY Donald Dwyer, New York State DOT, Albany, NY Ian M. Friedland, Federal Highway Administration, McLean, VA Michael G. Katona, Gig Harbor, WA Scott M. Olson, University of Illinois–Urbana-Champaign, Urbana, IL M. “Saiid” Saiidi, University of Nevada–Reno, Reno, NV Anoosh Shamsabadi, California DOT, Irvine, CA Munindra Talukdar, Washington State DOT, Tumwater, WA Jerry A. DiMaggio, FHWA Liaison G. P. Jayaprakash, TRB Liaison AUTHOR ACKNOWLEDGMENTS Work for the NCHRP 12-70 Project was carried out by a Project Team led by CH2M HILL of Bellevue, Washington, with major support from Earth Mechanics, Inc. of Fountain Valley, California and Parsons Brinckerhoff Inc. of New York City, New York. Leadership for the Project Team was provided by the fol- lowing individuals: Dr. Donald Anderson, P.E. from CH2M HILL in Bellevue, Washington, who was the project manager for the work; Professor Geoffrey R. Martin, P.E. from the University of Southern Cali- fornia, who served as a Principal Investigator; Mr. Ignatius (Po) Lam, P.E. from Earth Mechanics, who served as another Principal Investigator; and Dr. J.N. (Joe) Wang, P.E. from Parsons Brinckerhoff, who also served as a principal investigator. The Project included a Technical Advisory Panel that provided technical input to the Project at various points during the project duration. The panel members included: Professor Robert Holtz, P.E. from the University of Washington; Dr. Lee Marsh, P.E. from Berger ABAM in Federal Way, Washington; Profes- sor Edward Kavazanjian, P.E. from Arizona State University; and Professor Tom O’Rourke, P.E. from Cor- nell University A number of other individuals provided important input to the project, including Mr. Tony Allen, P.E., Chief Geotechnical Engineer with the Washington State Department of Transportation, and Dr. Anoosh Shamsabadi, P.E, structural research engineer with the California Department of Transportation (Cal- trans). The practical feedback from both individuals was particularly helpful. Mr. Amir Zand and Dr. Hubert Law from Earth Mechanics also provided major support by conducting analyses and assisting with the development of example problems. 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

This report provides analytical and design methods for the seismic design of retaining walls, buried structures, slopes, and embankments. The report details the development of the design procedures. Recommended LRFD specifications and design examples illustrat- ing the application of the design methods and specifications are included in an Appendix. The material in this report will be of immediate interest to roadway and bridge designers. A comprehensive load and resistance factor design (LRFD) specification for the seismic design of highway bridges has been developed by AASHTO. Those specifications reflect the latest bridge design philosophies for achieving high levels of seismic performance. Because these specifications are limited to highway bridges and components that are directly at- tached to them, such as abutments and wing walls, they do not address new or improved analytical methods or seismic design provisions for retaining walls, buried structures, slopes, or embankments. The objective of NCHRP Project 12-70 was to remove the limitations of the current spec- ifications through the development of analytical and design methods for the seismic design of retaining walls, buried structures, slopes, and embankments. This research was managed by Donald Anderson, CH2M HILL, Bellevue, Washington, with the assistance of Geoffrey Martin, University of Southern California; Po Lam, Earth Mechanics; and Joe Wang, Parson Brinckerhoff, New York. The report fully documents the program used to develop the design procedures. The Final Report is organized into two volumes. Volume 1 is published here as NCHRP Report 611. Volume 2 is available at the TRB website at http://trb.org/news/blurb_detail. asp?id=9631. F O R E W O R D By David B. Beal Staff Officer Transportation Research Board

C O N T E N T S V O L U M E 1 Final Report 1 Chapter 1 Introduction 1 1.1 Overall Project Objectives, Approach, and Schedule 2 1.2 Project Background 2 1.2.1 Plans for Implementing the LRFD Design Methodology 4 1.2.2 Overview of Conclusions from Initial Phase of Work 5 1.2.3 Overview of Conclusions from Second Phase of Work 7 1.2.4 Overview of Conclusions from Third Phase of Work 8 1.3 Organization of Final Report 8 1.3.1 Volume 1—Final Project Report 9 1.3.2 Volume 2—Recommended Specifications, Commentaries, and Example Problems 10 Chapter 2 Data Collection and Review 10 2.1 Earthquake Design Basis 11 2.2 Literature Search 12 2.2.1 Key References 14 2.2.2 General Observations 15 2.3 DOT, Vendor, and Consultant Contacts 17 2.4 Conclusions 18 Chapter 3 Problems and Knowledge Gaps 18 3.1 Retaining Walls 18 3.1.1 Gravity and Semi-Gravity Walls 21 3.1.2 MSE Retaining Walls 22 3.1.3 Soil Nail Walls 22 3.2 Slopes and Embankments 22 3.2.1 Seismic Considerations for Soil Slopes 23 3.2.2 Seismic Considerations for Rock Slopes 24 3.3 Buried Structures 25 3.4 Conclusions 26 Chapter 4 Work Plan: Analytical Methodologies 26 4.1 Developments for Seismic Ground Motions 28 4.2 Developments for Retaining Walls 28 4.2.1 Generalized Limit Equilibrium Analyses 29 4.2.2 Wall Height-Dependent Seismic Coefficient 30 4.2.3 Deformation Analyses 30 4.3 Developments for Slopes and Embankments 31 4.4 Developments for Buried Structures 31 4.4.1 Analysis Procedures for TGD 33 4.4.2 Analysis Procedures for Permanent Ground Deformations (PGD) 33 4.5 Summary

35 Chapter 5 Seismic Ground Motions 35 5.1 Seismic Loading Criteria 35 5.1.1 Update to AASHTO Seismic Ground Motion Criteria 38 5.1.2 Range of Ground Shaking Levels in the United States for Referenced Soft Rock 39 5.1.3 Variation in Spectral Shapes for Soil and Rock Sites in WUS versus CEUS 41 5.2 Newmark Displacement Correlations 41 5.2.1 Approach for Updating Newmark Charts 41 5.2.2 Description of Ground Motion Database 42 5.2.3 Permanent Displacement Data 42 5.2.4 Microsoft Access Database 43 5.2.5 Spectral Acceleration Characteristics 43 5.2.6 Correlation between PGV and S1, PGA and M 43 5.2.7 Newmark Sliding Block Displacement Correlations 46 5.2.8 Comparison Between Correlations 48 5.2.9 Confidence Level 49 5.2.10 Design Recommendations 49 5.3 Correlation of PGV with S1 54 5.4 Conclusions 55 Chapter 6 Height-Dependent Seismic Coefficients 55 6.1 Wave Scattering Evaluations 55 6.1.1 Scattering Analyses for a Slope 63 6.1.2 Scattering Analyses for Retaining Walls 66 6.2 Conclusions 68 Chapter 7 Retaining Walls 68 7.1 Current Design Practice 71 7.2 The M-O Method and Limitations 71 7.2.1 Seismic Active Earth Pressures 73 7.2.2 Seismic Passive Earth Pressures 74 7.3 M-O Earth Pressures for Cohesive Soils 74 7.3.1 Evaluation of the Contribution from Cohesion 74 7.3.2 Results of M-O Analyses for Soils with Cohesion 75 7.3.3 Implication to Design 76 7.4 GLE Approach for Determining Seismic Active Pressures 76 7.5 Height-Dependent Seismic Design Coefficients 77 7.5.1 Evaluation of Impedance Contrasts and Soil Behavior 79 7.5.2 Results of Impedance Contrast and Nonlinearity Evaluations 81 7.6 Displacement-Based Design for Gravity, Semi Gravity, and MSE Walls 82 7.7 Conventional Gravity and Semi-Gravity Walls—Recommended Design Method for External Stability 84 7.8 MSE Walls—Recommended Design Methods 84 7.8.1 Current Design Methodology 84 7.8.2 MSE Walls—Design Method for External Stability 87 7.8.3 MSE Walls—Design Method for Internal Stability 88 7.9 Other Wall Types 88 7.9.1 Nongravity Cantilevered Walls 91 7.9.2 Anchored Walls 93 7.9.3 Soil Nail Walls 94 7.10 Conclusions

96 Chapter 8 Slopes and Embankments 96 8.1 Types and Performance of Slopes 96 8.1.1 Engineered Slopes and Embankments 97 8.1.2 Natural Slopes 97 8.2 Current Practice 97 8.2.1 Limit Equilibrium Approach 99 8.2.2 Displacement-Based Approach 100 8.3 Proposed Design Methodology 101 8.3.1 Limit Equilibrium Approach 101 8.3.2 Displacement-Based Approach 101 8.4 Example Application 101 8.4.1 Problem Description 102 8.4.2 Results 102 8.5 Other Considerations 102 8.5.1 Limit Equilibrium Design Methods 103 8.5.2 No Analysis Cut-off 103 8.5.3 Liquefaction Potential 104 8.6 Conclusions 105 Chapter 9 Buried Structures 105 9.1 Seismic Performance of Culverts and Pipelines 105 9.2 Culvert/Pipe Characteristics 106 9.2.1 Flexible Culverts and Pipes 106 9.2.2 Rigid Culverts and Pipes 106 9.3 General Effects of Earthquakes and Potential Failure Modes 107 9.3.1 Ground Shaking 108 9.3.2 Ground Failure 108 9.4 Current Seismic Design Practice for Culverts or Other Buried Structures 109 9.5 General Methodology and Recommended Procedures 109 9.5.1 Ovaling of Circular Conduits 113 9.5.2 Racking of Rectangular Conduits 115 9.6 Parametric and Verification Analysis 115 9.6.1 Types of Structures and Other Parameters Used in Evaluation 115 9.6.2 Model Assumptions and Results 129 9.7 Conclusions and Recommendations 131 Chapter 10 Recommendations for Future Work 131 10.1 Ground Motions and Displacements 131 10.2 Retaining Walls 132 10.3 Slopes and Embankments 133 10.4 Buried Structures 133 10.5 Need for Confirming Methods 134 References 137 Appendices