Improved Simplified Method for Prediction of Loads in Reinforced Soil Walls
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VIEW THE REPLYPublication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 141, Issue 11
Abstract
The Simplified Method as reported in AASHTO and Federal Highway Administration (FHWA) manuals has been demonstrated to give poor predictions of unfactored reinforcement loads and strains, especially for geosynthetic reinforced soil walls. The writers have proposed the K-stiffness Method to improve the load prediction accuracy for walls under working stress (operational) conditions. However, it has also been recognized in recent publications by the writers and others that further improvements to the K-stiffness Method are needed. Furthermore, acceptance of the K-stiffness Method has been hindered due to its perceived complexity and the use of the plane strain friction angle to quantify the strength of the reinforced soil. This paper takes a fresh look at both methods and uses lessons learned from the K-stiffness Method development to improve the accuracy of the AASHTO/FHWA Simplified Method. Key parameters introduced during the development of the K-stiffness Method are applied to the Simplified Method and updated to further improve load prediction accuracy. Additional wall case histories have been added to the database used for the original K-stiffness Method to calibrate the new model and to broaden its utility. An important improvement is a single model that allows for seamless load prediction across a range of walls constructed with relatively extensible geosynthetic reinforcement and inextensible steel reinforcement materials. The quantitative improvement of the new model (Simplified Stiffness Method) compared to the current AASHTO/FHWA Simplified Method is demonstrated through statistical analysis of load bias values (i.e., the ratio of measured to predicted reinforcement load).
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Acknowledgments
The work reported in this paper was part of a pooled fund research program supported by grants from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Ministry of Transportation of Ontario, the Department of National Defence (Canada) and the following state departments of transportation in the USA: Alaska, Arizona, California, Colorado, Idaho, Minnesota, New York, North Dakota, Oregon, Utah, Washington, and Wyoming.
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Journal of Geotechnical and Geoenvironmental Engineering
Volume 141 • Issue 11 • November 2015
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Jun 7, 2014
Accepted: Apr 24, 2015
Published online: Jun 9, 2015
Published in print: Nov 1, 2015
Discussion open until: Nov 9, 2015
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