U.S. Department of Transportation
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 |
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| Publication Number: FHWA-HRT-14-094 Date: February 2015 |
Publication Number:
FHWA-HRT-14-094
Date: February 2015 |
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Geosynthetic reinforced soil (GRS) for load-bearing applications has been identified by the Federal Highway Administration (FHWA) as a proven, market-ready technology and is being actively promoted through the agency’s Every Day Counts initiative. With the publication of the FHWA interim design guidance for GRS abutments and integrated bridge systems, presented in GRS Integrated Bridge System (IBS) Interim Implementation Guide (FHWA-HRT-11-026), FHWA took the first steps to differentiate the design of GRS and conventional, larger-spaced geosynthetic mechanically stabilized earth (GMSE). This was based on considerable research and the change in behavior observed when reinforcement is closely spaced (i.e., less than about 12 inches (30.48 cm)). Because of its similarities to GMSE walls, however, there are some misconceptions about the design and behavior of closely spaced GRS systems. This synthesis report outlines the background and research for some of the most pertinent changes related to the design differences between GRS and GMSE: embedment length, reinforcement pullout, eccentricity, lateral earth pressures and connection strength, the W equation for required reinforcement strength, and long-term reduction factors for geosynthetic materials. This report can be used by transportation agencies to support design changes related to closely spaced GRS systems.
Jorge E. Pagán-Ortiz
Director, Office of Infrastructure
Research and Development
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