Working Stress Behavior of Tall Steel Mechanically Stabilized Earth (MSE) Walls

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This research seeks to transform the way Mechanically Stabilized Earth (MSE) walls are analyzed, resulting in a broad impact due to: (1) the improvement in the understanding of the impact of fundamental soil behavior on the assessment of reinforced soil, mitigating the economic costs of inefficient wall design; (2) the dissemination of field performance data and implementation of advanced numerical models to assist students, practitioners, and researchers in studying the behavior of tall MSE walls; and (3) the generation of an advanced interactive visualization tool developed in collaboration with students designed for education and engineering recruitment. Tens of thousands of MSE retaining walls have been constructed in the United States since their introduction in 1972. MSE walls are being constructed to greater heights, in non-linear geometries, and with multiple tiers and tight reinforcement spacing. The use of these cost-effective reinforced soil structures will continue to grow in the U.S. due to increasing urbanization, diminishing right-of-way, and/or wetland mitigation. Despite the proliferation of wall construction and advances in materials and methods, our ability to predict the working stress behavior and displacement of tall, single and multi-tier walls is unsatisfactory. The behavior of steel MSE walls constructed to 15 meters in height, which require typical reinforcement spacing of 0.5 to 0.75 m, is not significantly affected by curvature of the Mohr Failure envelope, nor the potential for frictional interference possible with more closely spaced reinforcements. However, as steel MSE walls are constructed with much greater heights and closer reinforcement spacing, the role of soil dilation and potential frictional interference between reinforcement strips become critical. Recently, some MSE wall heights have exceeded 40 m. This research aims to determine the role of soil dilation and confining stress, and frictional interference on the development of reinforcement strains through a coordinated experimental program and numerical modeling study. These results will be used to model the field behavior observed in instrumented MSE walls reported in the literature, as well as improve design models for the determination of internal stability and displacement.The impact of this research will be experienced worldwide as the design and construction of tall MSE walls proliferates to meet society's needs. An improved understanding of the effect of soil dilation and frictional interference on the working stress behavior of steel reinforcements represents an important step towards the revolution of the analysis of tall reinforced soil walls. The dissemination of high-quality performance data, numerical model codes, and educational tools will serve society by allowing researchers, educators, and professional engineers to directly access and evaluate tall wall behavior.