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Publication Number:  FHWA-HRT-15-080    Date:  February 2016
Publication Number: FHWA-HRT-15-080
Date: February 2016

 

Synthesis and Evaluation of The Service Limit State of Engineered Fills for Bridge Support

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FOREWORD

Engineered fills, including compacted granular fill and reinforced soil, are a cost-effective alternative to conventional bridge foundation systems; however, limited guidance exists on estimating the settlement and lateral deformation of these features under service conditions. Additionally, the stress distribution within these features is not well understood, leading to uncertainty in performance. To address these gaps, the Federal Highway Administration initiated a study to evaluate the service limit state (SLS) design and analysis of engineered fills for bridge support. This synthesis report is the product of an extensive literature search on current practices, available load tests, and numerical modeling results. It presents factors impacting the service limit of engineered fills and also provides a preliminary analysis on the reliability of existing prediction methods. The summarization of this work will assist in the continued development of research efforts to establish SLS design guidance for the use of engineered fills. This report will be of interest to engineers involved with bridge foundation research and design.

Jorge E. Pagán-Ortiz
Director, Office of Infrastructure
Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

 

Technical Report Documentation Page

1. Report No.

FHWA-HRT-15-080

2. Government Accession No. 3 Recipient's Catalog No.
4. Title and Subtitle

Synthesis and Evaluation of the Service Limit State of Engineered Fills for Bridge Support

5. Report Date

February 2016

6. Performing Organization Code
7. Author(s)

Xiao, M., Qiu, T., Khosrojerdi, M., Basu, P., and Withiam, J.L.

8. Performing Organization Report No.

 

9. Performing Organization Name and Address

The Larson Transportation Institute
The Pennsylvania State University
201 Transportation Research Building
University Park, PA 16802

D’Appolonia Engineering Division of Ground Technology, Inc.
275 Center Road #2
Monroeville, PA 15146

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH61-14-C-00012

12. Sponsoring Agency Name and Address

Office of Infrastructure Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296

13. Type of Report and Period Covered

Technical

14. Sponsoring Agency Code

 

15. Supplementary Notes

The Contracting Officer’s Representative (COR) was Jennifer Nicks, HRDI-40. Additional Federal Highway Administration technical consultants included Naser Abu-Hejleh, Michael Adams, and Khalid Mohamed.

16. Abstract

This report synthesizes the current service limit state (SLS) design and analyses of engineered fills for bridge support used as shallow foundations. The SLS for settlement and deformations of bridge supports are summarized. Extensive literature reviews were conducted to synthesize the effects of various parameters on the SLS of engineered fills. The reliability of current prediction methods for deformations of bridge supports on granular soils are presented and evaluated using measured deformation data in the literature. Based on the literature review and synthesis, knowledge gaps and data needs for bridge supports with engineered fills were identified.

17. Key Words

Engineered fills, Settlement, Deformations, Service limit state, Bridge abutment, Shallow foundation, Geosynthetic reinforced soil, Mechanically stabilized earth, Reinforced soil foundation

18. Distribution Statement

No restrictions. The report will be available to the public at FHWA: www.fhwa.dot.gov/research or NTIS: www.ntis.gov.

19. Security Classification
(of this report)

Unclassified

20. Security Classification
(of this page)

Unclassified

21. No. of Pages

151

22. Price

N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

SI* (Modern Metric) Conversion Factors

TABLE OF CONTENTS

CHAPTER 1. OVERVIEW OF BRIDGE SUPPORTS USING ENGINEERED FILLS

CHAPTER 2. CURRENT SLS DESIGN PROCEDURES AND CRITERIA

CHAPTER 3. LITERATURE REVIEW OF PREVIOUS WORK IN ENGINEERED FILLS FOR BRIDGE SUPPORTS

CHAPTER 4. EVALUATION OF PREDICTION METHODS FOR DEFORMATIONS OF BRIDGE SUPPORTS ON GRANULAR SOILS

CHAPTER 5. NUMERICAL AND CONSTITUTIVE MODELS FOR COMPACTED FILL AND REINFORCED SOIL FOR BRIDGE SUPPORTS

CHAPTER 6. CONCLUSIONS

REFERENCES

LIST OF FIGURES

 

List of Tables

 

List of Abbreviations and Symbols

Abbreviations

   
3D three-dimensional  
AASHTO American Association of State Highway and Transportation Officials  
ADOT Arizona Department of Transportation  
CR covering ratio  
CMU Concrete Masonry Unit  
COV coefficient of variation  
CTI Colorado Transportation Institute  
DC Defiance County, OH  
EOC end of construction  
FE finite element  
FEA finite element analysis  
FEM finite element method  
FHWA Federal Highway Administration  
GRS geosynthetic reinforced soil  
GSGC generic soil geosynthetic composite  
IBS integrated bridge system  
LRFD load and resistance factor design  
LTDS long-term design strength  
LVDT linear voltage displacement transducer  
MSE mechanically stabilized earth  
NHI National Highway Institute  
PET polyester  
POT potentiometer  
PI Plasticity Index  
PP polypropylene  
PT performance test  
RC relative compaction  
RSF reinforced soil foundation  
SHRP Strategic Highway Research Program  
SLS service limit state  
SPT standard penetration test  
SRW segmental retaining wall  
TF Turner-Fairbank  
TFHRC Turner-Fairbank Highway Research Center  
ULS ultimate limit state  
UX uniaxial  
WSDOT Washington State Department of Transportation  
WWM welded wire mesh  

Symbols

   
a footing offset from the edge of the wall face (i.e., setback distance)  
B width of foundation  
b length of reinforcement layers below foundation  
b' width of facing block  
bq,vol width of the load along the top of the wall (including the setback)  
c cohesion  
C1 correction factor for strain relief due to soil excavation for foundation embedment used in Schmertmann method  
C2 correction factor to consider creep as the time-dependent increase in settlement for t number of years after construction used in Schmertmann method  
d depth of bearing bed reinforcement  
dmax maximum aggregate size  
Df depth of embedment of foundation  
DL lateral displacement of GRS abutments in response to a vertical load  
DR soil relative density  
Dv vertical settlement in the GRS abutment  
D10 particle diameter at which 10 percent of the sample is finer, by mass  
EGRS Young’s elastic modulus of GRS composition  
ER elastic modulus of reinforcement  
Es elastic modulus of soil  
h spacing of reinforcement layers  
H height of abutment/pier  
Hi thickness of each soil layer  
kb interface stiffness between backfill soil and reinforcement layers  
Kh horizontal earth pressure coefficient  
Kreinf stiffness of reinforcement  
L length of foundation/reinforcement layers within pier or abutment  
Las distance between adjacent supports  
Ltotal total length of foundation  
n time dependency exponent in time-dependent settlement equation  
N number of reinforcement layers  
N0 total number (population) of values  
N60 standard penetration number that is corrected based on the field conditions  
(N1)60 corrected SPT blow count  
N-value blow count for an SPT sampler to penetrate the second and third 6 inches into the subsoil  
p footing bearing pressure  
q applied pressure  
qc static cone resistance of cone penetration test  
R2 coefficient of determination  
Sv vertical spacing between reinforcement  
s/B ratio of settlement of foundation to its width  
Tf tensile strength  
t time  
tR thickness of reinforcement  
u embedment depth of top geogrid layer  
z standard normal variable  
Z depth from the crest of wall  
zi depth of influence zone  
δ/h lateral displacement of a GRS wall or abutment with flexible facing  
ΔH100 differential settlement 100 ft (30.5 m) within pier or abutment and between piers  
Δi lateral movement of a GRS wall with modular block facing  
Δp net uniform pressure applied at the foundation depth used in Schmertmann method  
γb bulk unit weight of facing (such as modular block)  
γs unit weight of soil  
εd strain limit  
μλ arithmetic mean of λ  
λi sampled λ value  
Φ friction angle  
Φds friction angle of soil based on direct shear test  
ψ dilation angle of soil  
δ friction angle between modular block facing elements  
δh lateral deformation of a GRS wall or abutment  
δmax maximum lateral deformation of a GRS wall or abutment  
δR relative displacement coefficient  
σ'0 initial average effective stress of the subdivided soil layer  
σ standard deviation  
μλ arithmetic mean of bias value  
λ bias value (ratio of the measured value to the predicted value)  

 

 

 

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