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Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
 |
| Publication Number: FHWA-HRT-15-080 Date: February 2016 |
Publication Number: FHWA-HRT-15-080 Date: February 2016 |
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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 |
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| 6. Performing Organization Code | ||||
| 7. Author(s)
Xiao, M., Qiu, T., Khosrojerdi, M., Basu, P., and Withiam, J.L. |
8. Performing Organization Report No.
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9. Performing Organization Name and Address The Larson Transportation Institute D’Appolonia Engineering Division of Ground Technology, Inc. |
10. Work Unit No. (TRAIS) |
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11. Contract or Grant No. DTFH61-14-C-00012 |
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| 12. Sponsoring Agency Name and Address
Office of Infrastructure Research and Development |
13. Type of Report and Period Covered
Technical |
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14. Sponsoring Agency Code
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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. |
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| 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. |
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| 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. |
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19. Security Classification Unclassified |
20. Security Classification Unclassified |
21. No. of Pages 151 |
22. Price N/A |
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| Form DOT F 1700.7 (8-72) | Reproduction of completed page authorized |
SI* (Modern Metric) Conversion Factors
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
Abbreviations |
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| 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 |
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| 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) |
