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

本研究旨在改变机械稳定土（MSE）墙体的分析方式，产生广泛的影响，因为：(1)提高了对基本土壤行为对加筋土评估影响的理解，减轻了低效墙体设计的经济成本；(2)现场性能数据的传播和先进数值模型的实施，以帮助学生、从业者和研究人员研究高MSE墙的行为；(3)与学生合作开发先进的交互式可视化工具，为教育和工程招聘设计。自1972年引入MSE挡土墙以来，美国已经建造了数万座MSE挡土墙。MSE墙体正在被建造到更高的高度，非线性几何形状，多层和紧密的加固间距。由于城市化程度的提高、路权的减少和/或湿地的减少，这些具有成本效益的加筋土结构的使用将在美国继续增长。尽管墙体结构的扩散和材料和方法的进步，我们预测高层、单层和多层墙体的工作应力行为和位移的能力并不令人满意。15米高的MSE钢墙，通常需要0.5到0.75 m的钢筋间距，其性能不会受到Mohr失效包络线曲率的显著影响，也不会受到更紧密的钢筋间距可能产生的摩擦干扰的影响。然而，由于钢MSE墙具有更高的高度和更紧密的钢筋间距，土体膨胀和钢筋条之间潜在的摩擦干扰的作用变得至关重要。最近，一些MSE墙高超过40米。本研究旨在通过协调的实验程序和数值模拟研究来确定土体膨胀、围应力和摩擦干扰对钢筋应变发展的作用。这些结果将用于模拟在文献中报道的仪器MSE墙中观察到的场行为，以及改进确定内部稳定性和位移的设计模型。随着高MSE墙的设计和建造激增，以满足社会的需求，这项研究的影响将在全球范围内得到体验。提高对土体膨胀和摩擦干扰对钢筋工作应力行为的影响的理解是对高层加筋土墙分析革命的重要一步。高质量性能数据、数值模型代码和教育工具的传播将使研究人员、教育工作者和专业工程师能够直接访问和评估高层墙体的行为，从而为社会服务。

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.