Methods Used in Tieback Wall Design and Construction to Prevent Local Anchor Failure

184 Pages·2003·1.11 MB·English

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Innovations for Navigation Projects Research Program
Methods Used in Tieback Wall Design and
Construction to Prevent Local Anchor

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Ralph W. Strom and Robert M. Ebeling December 2002
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Approved for public release; distribution is unlimited.

Innovations for Navigation Projects ERDC/ITL TR-02-11
Research Program December 2002
Methods Used in Tieback Wall Design and
Construction to Prevent Local Anchor Failure,
Progressive Anchorage Failure, and Ground
Mass Stability Failure
Ralph W. Strom
9474 SE Carnaby Way
Portland, OR 97266
Concord, MA 01742-2751
Robert M. Ebeling
Information Technology Laboratory
U.S. Army Engineer Research and Development Center
3909 Halls Ferry Road
Vicksburg, MS 39180-6199

Final report

Approved for public release; distribution is unlimited.

Prepared for U.S. Army Corps of Engineers
Washington, DC 20314-1000

Under INP Work Unit 33272
ABSTRACT: A local failure that spreads throughout a tieback wall system can result in progressive
collapse. The risk of progressive collapse of tieback wall systems is inherently low because of the
capacity of the soil to arch and redistribute loads to adjacent ground anchors. The current practice of the
U.S. Army Corps of Engineers is to design tieback walls and ground anchorage systems with sufficient
strength to prevent failure due to the loss of a single ground anchor.
Results of this investigation indicate that the risk of progressive collapse can be reduced by using
performance tests, proof tests, extended creep tests, and lift-off tests to ensure that local anchor failures
will not occur and to ensure the tieback wall system will meet all performance objectives; by using yield
line (i.e., limit state) analysis to ensure that failure of a single anchor will not lead to progressive failure of
the tieback wall system; by verifying (by limiting equilibrium analysis) that the restraint force provided
by the tieback anchors provides an adequate margin of safety against an internal stability failure; and by
verifying (by limiting equilibrium analysis) that the anchors are located a sufficient distance behind the
wall face to provide an adequate margin of safety against external stability (ground mass) failure.
Design measures that can be used to protect against local anchor failure are described, along with
testing methods that can be used to ensure that anchor performance meets project performance objectives.
Examples are given to demonstrate the yield line analysis techniques that are used to verify that the wall
system under the “failed anchor” condition can safely deliver loads to adjacent anchors and to ensure that
the failure of a single anchor will not lead to progressive wall failure are. Limiting equilibrium analysis
procedures used for the internal and external stability of tieback wall systems are also described. Simple
procedures applicable to “dry” homogeneous sites and general-purpose slope stability programs
applicable to layered sites (with and without a water table) are also illustrated by example.

DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes.
Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products.
All product names and trademarks cited are the property of their respective owners. The findings of this report are not
to be construed as an official Department of the Army position unless so designated by other authorized documents.
DESTROY THIS REPORT WHEN IT IS NO LONGER NEEDED. DO NOT RETURN TO THE ORIGINATOR.
Contents
Preface................................................................................................................................vi

Conversion Factors, Non-SI to SI Units of Measurement................................................vii

1(cid:151)Introduction................................................................................................................1-1

1.1 Preventing Progressive Anchor System Failure−Corps Practice...................1-1
1.2 Preventing Progressive Collapse of Tieback Wall Systems..........................1-1

2(cid:151)Preventing Local Anchor Failures.............................................................................2-1

2.1 General...........................................................................................................2-1
2.2 Ground Anchor Design..................................................................................2-1
2.2.1 Maximum design load..........................................................................2-1
2.2.2 Ground anchor lock-off load................................................................2-2
2.2.3 Verifying lock-off loads through lift-off testing..................................2-3
2.3 Acceptance Criteria........................................................................................2-3
2.3.1 Creep....................................................................................................2-4
2.3.2 Apparent free length............................................................................2-4
2.4 Ground Anchor Acceptance Decision Tree...................................................2-5
2.4.1 Anchors that pass apparent free-length criterion.................................2-6
2.4.2 Anchors that fail minimum apparent free-length criterion..................2-6
2.5 Modification of Design or Installation Procedures........................................2-7

3(cid:151)Anchor Testing...........................................................................................................3-1

3.1 General...........................................................................................................3-1
3.2 Details............................................................................................................3-2
3.2.1 Concepts for monitoring anchor bond zone capacity..........................3-3
3.2.2 Anchor load testing..............................................................................3-3

4(cid:151)Preventing Progressive Anchor Failure.....................................................................4-1

4.1 Introduction....................................................................................................4-1
4.2 Wall Evaluation.............................................................................................4-3
4.2.1 Flexural capacity of CIP facing...........................................................4-3
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4.2.2 Shear capacity of CIP facing................................................................4-4
4.2.3 Punching shear capacity of soldier beam headed-stud to CIP
facing connection..............................................................................4-4
4.2.4 Tensile strength capacity of headed-stud connections.........................4-5
4.2.5 Flexural capacity of soldier beams......................................................4-5
4.3 Anchor Evaluation.........................................................................................4-6
4.3.1 Tensile capacity of anchors..................................................................4-7
4.3.2 Pullout capacity of grout/ground bond................................................4-7
4.3.3 Pullout capacity of tendon/grout bond.................................................4-7
4.4 Defensive Design Considerations..................................................................4-7
4.4.1 Redundant load paths and cap beams..................................................4-8
4.4.2 Ductile members and connections.......................................................4-9
4.4.3 Quality of design, materials, and construction.....................................4-9
4.5 Research and Development Needs ..............................................................4-10

5(cid:151)Internal and External Stability...................................................................................5-1

5.1 Introduction ...................................................................................................5-1
5.2 Factors of Safety for Internal and External Stability Evaluations.................5-2
5.3 Evaluation of Internal Stability......................................................................5-2
5.4 Evaluation of External Stability.....................................................................5-3
5.5 Use of GPSS Programs for Evaluating Internal and External Stability.........5-4
5.6 Internal Stability of Anchored Wall Systems(cid:150)Analysis Details....................5-4
5.6.1 Simplified limiting equilibrium approach............................................5-5
5.6.2 CSLIDE................................................................................................5-5
5.6.3 UTEXAS4............................................................................................5-7
5.7 External Stability of Anchored Wall Systems(cid:150)Analysis Details ..................5-8
5.7.1 Simplified limiting equilibrium approach............................................5-8
5.7.2 CSLIDE................................................................................................5-9
5.7.3 UTEXAS4..........................................................................................5-10
5.8 Cohesive Soils..............................................................................................5-10
5.9 Summary and Conclusions..........................................................................5-11
5.10 Recommendations for Research..................................................................5-12

References....................................................................................................................Ref-1

Appendix A: Design Calculations for Soldier Beam Wall ...........................................A-1

Appendix B: Internal Stability, 30-ft-High Wall(cid:150)Retained Soil Dry ............................B-1

Appendix C: Internal Stability, 30-ft-High Wall(cid:150)Partially Submerged ........................C-1

Appendix D: External Stability, 30-ft-High Wall(cid:150)Single Anchor ................................D-1

Appendix E: External Stability, 30-ft-High Wall(cid:150)Two Anchors ..................................E-1

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Appendix F: Layered Soil System(cid:150)Internal and External Stability ...............................F-1

SF 298

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Preface
The study described in this report was authorized by Headquarters, U.S. Army Corps
of Engineers (HQUSACE), as part of the Innovations for Navigation Projects (INP)
Research Program. The study was conducted under Work Unit (WU) 33272, (cid:147)Soil-
Structure Interaction Studies of Walls with Multiple Rows of Anchors.(cid:148)

Dr. Tony C. Liu was the INP Coordinator at the Directorate of Research and
Development, HQUSACE; Research Area Manager was Mr. Barry Holliday,
HQUSACE; and Program Monitors were Mr. Mike Kidby and Ms. Anjana Chudgar,
HQUSACE. Mr. William H. McAnally of the ERDC Coastal and Hydraulics Laboratory
was the Lead Technical Director for Navigation Systems; Dr. Stanley C. Woodson,
ERDC Geotechnical and Structures Laboratory (GSL), was the INP Program Manager.

This report was prepared by Mr. Ralph W. Strom, Portland, OR, and Dr. Robert M.
Ebeling, U.S. Army Engineer Research and Development Center (ERDC), Information
Technology Laboratory (ITL). The research was monitored by Dr. Ebeling, Principal
Investigator for WU 33272, under the supervision of Mr. H. Wayne Jones, Chief,
Computer-Aided Engineering Division, ITL; Dr. Jeffery P. Holland, Director, ITL; and
Dr. David R. Pittman, Acting Director, GSL.

At the time of publication of this report, Dr. James R. Houston was Director of
ERDC, and COL John W. Morris III, EN, was Commander and Executive Director.

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Conversion Factors, Non-SI to
SI Units of Measurement
Non-SI units of measurement used in this report can be converted to SI units as follows:

Multiply By To Obtain
degrees (angle) 0.01745329 radians
feet 0.3048 meters
foot-pounds (force) 1.355818 joules
inches 25.4 millimeters
inch-pounds (force) 0.1129848 joules
kips (force) 4.448222 kilonewtons
kips (force) per square foot 47.88026 kilopascals
kips (force) per square inch 6.894757 megapascals
pounds (force) per square foot 47.88026 pascals
pounds (force) per square inch 6.894757 kilopascals

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